### AsyncClientClass Setup and Control

Source: https://context7.com/mobizt/firebaseclient/llms.txt

Illustrates the setup and configuration of the AsyncClientClass for managing asynchronous Firebase operations. It covers basic construction, independent queues, SSL client options, and timeout settings.

```cpp
#include <WiFiClientSecure.h>
#include <FirebaseClient.h>

WiFiClientSecure ssl1, ssl2;
using AsyncClient = AsyncClientClass;

// Basic constructor — uses WiFi reconnection by default
AsyncClient aClient(ssl1);

// Two clients for independent stream and request queues
AsyncClient aClientStream(ssl1), aClientReq(ssl2);

// Configure SSL client options
ssl1.setInsecure();
ssl1.setConnectionTimeout(1000); // ms (ESP32 SDK v3+)
ssl1.setHandshakeTimeout(5);     // seconds (ESP32 SDK v3+)
// ssl1.setBufferSizes(4096, 1024); // ESP8266 only

// Set timeouts on the async client
aClient.setSyncSendTimeout(10);  // seconds
aClient.setSyncReadTimeout(10);
aClient.setSessionTimeout(300);

// Check last error after a sync (await) call
if (aClient.lastError().code() != 0) {
    Firebase.printf("Error: %s, code: %d\n",
        aClient.lastError().message().c_str(),
        aClient.lastError().code());
}

// Stop a specific running task by UID
aClient.stopAsync("myTaskUID");

// Stop all tasks in queue
aClient.stopAsync(true);

// Get pending task count
size_t pending = aClient.taskCount();
```

--------------------------------

### Install FirebaseClient with PlatformIO

Source: https://github.com/mobizt/firebaseclient/blob/main/README.md

Use this command to install the FirebaseClient library in PlatformIO IDE. Ensure your platform-espressif32 core is up-to-date or use the pioarduino platform for ESP32.

```bash
pio lib install "FirebaseClient"
```

--------------------------------

### get (String)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/messaging_instance.md

Retrieves information about app instances.

```APIDOC
## get (String)

### Description
Get information about app instances.

### Method
String

### Signature
`String get(AsyncClientClass &aClient, const String &IID)`

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `IID` (const String&) - The instance ID token.

### Returns
- `String` - The response payload.
```

--------------------------------

### Begin Transaction

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firestore_database.md

Starts a new transaction. The Firebase project ID should be the name without 'firebaseio.com'.

```cpp
String beginTransaction(AsyncClientClass &aClient, const Firestore::Parent &parent, const TransactionOptions &transOptions)
```

--------------------------------

### AsyncClientClass Setup and Control

Source: https://context7.com/mobizt/firebaseclient/llms.txt

Details on setting up and managing the `AsyncClientClass` for asynchronous operations, including constructor options, SSL client configuration, and task management.

```APIDOC
## `AsyncClientClass` — Async Client Setup and Control

`AsyncClientClass` wraps an SSL client and manages the async task queue for all Firebase service operations. One client can serve multiple services when auth is handled by the same `FirebaseApp`.

```cpp
#include <WiFiClientSecure.h>
#include <FirebaseClient.h>

WiFiClientSecure ssl1, ssl2;
using AsyncClient = AsyncClientClass;

// Basic constructor — uses WiFi reconnection by default
AsyncClient aClient(ssl1);

// Two clients for independent stream and request queues
AsyncClient aClientStream(ssl1), aClientReq(ssl2);

// Configure SSL client options
ssl1.setInsecure();
ssl1.setConnectionTimeout(1000); // ms (ESP32 SDK v3+)
ssl1.setHandshakeTimeout(5);     // seconds (ESP32 SDK v3+)
// ssl1.setBufferSizes(4096, 1024); // ESP8266 only

// Set timeouts on the async client
aClient.setSyncSendTimeout(10);  // seconds
aClient.setSyncReadTimeout(10);
aClient.setSessionTimeout(300);

// Check last error after a sync (await) call
if (aClient.lastError().code() != 0) {
    Firebase.printf("Error: %s, code: %d\n",
        aClient.lastError().message().c_str(),
        aClient.lastError().code());
}

// Stop a specific running task by UID
aClient.stopAsync("myTaskUID");

// Stop all tasks in queue
aClient.stopAsync(true);

// Get pending task count
size_t pending = aClient.taskCount();
```
```

--------------------------------

### get(AsyncClientClass &aClient, const String &projectId, const String &rulesetId, AsyncResultCallback cb, const String &uid = "")

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/rules.md

Get a Ruleset by name including the full Source contents.

```APIDOC
## void get(AsyncClientClass &aClient, const String &projectId, const String &rulesetId, AsyncResultCallback cb, const String &uid = "")

### Description
Get a Ruleset by name including the full Source contents.

### Signature
```cpp
void get(AsyncClientClass &aClient, const String &projectId, const String &rulesetId, AsyncResultCallback cb, const String &uid = "")
```

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `projectId` (const String&) - The project ID.
- `rulesetId` (const String&) - The ruleset ID.
- `cb` (AsyncResultCallback) - The async result callback.
- `uid` (const String&) - The user specified UID of async result (optional).
```

--------------------------------

### Declare RealtimeDatabase Class

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/realtime_database.md

Declares the RealtimeDatabase class. No setup required.

```cpp
class RealtimeDatabase
```

--------------------------------

### Get App Instance Information (AsyncResult)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/messaging_instance.md

Retrieve information about a specific app instance using its instance ID token and store the result in an AsyncResult object. This is a synchronous way to get instance details.

```cpp
void get(AsyncClientClass &aClient, const String &IID, AsyncResult &aResult)
```

--------------------------------

### String get(AsyncClientClass &aClient, const String &projectId, const String &releaseId)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/rules.md

Retrieves a specific Release by its name and returns its details as a String.

```APIDOC
## Function: get

### Description
Get a Release by name.

### Signature
```cpp
String get(AsyncClientClass &aClient, const String &projectId, const String &releaseId)
```

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `projectId` (const String&) - The project ID.
- `releaseId` (const String&) - The release ID.

### Returns
- `String` - The response payload.
```

--------------------------------

### get (AsyncResult)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/messaging_instance.md

Retrieves information about app instances asynchronously.

```APIDOC
## get (AsyncResult)

### Description
Get information about app instances.

### Method
void

### Signature
`void get(AsyncClientClass &aClient, const String &IID, AsyncResult &aResult)`

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `IID` (const String&) - The instance ID token.
- `aResult` (AsyncResult&) - The async result.
```

--------------------------------

### get (AsyncResultCallback)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/messaging_instance.md

Retrieves information about app instances asynchronously with a callback.

```APIDOC
## get (AsyncResultCallback)

### Description
Get information about app instances.

### Method
void

### Signature
`void get(AsyncClientClass &aClient, const String &IID, AsyncResultCallback cb, const String &uid = "")`

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `IID` (const String&) - The instance ID token.
- `cb` (AsyncResultCallback) - The async result callback.
- `uid` (const String&) - The user specified UID of async result (optional).
```

--------------------------------

### Default Constructor for AsyncClientClass

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/async_client.md

Initializes an AsyncClientClass with default settings. No specific setup is required.

```cpp
AsyncClientClass()
```

--------------------------------

### Get App Instance Information (String)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/messaging_instance.md

Retrieve information about a specific app instance using its instance ID token. This function returns the response payload as a String.

```cpp
String get(AsyncClientClass &aClient, const String &IID)
```

--------------------------------

### Get DOM Element by ID

Source: https://github.com/mobizt/firebaseclient/blob/main/examples/RealtimeDatabase/StreamPerformanceTest/index.html

A utility function to get a DOM element by its ID. It's a shorthand for document.getElementById.

```javascript
function getEl(e){return document.getElementById(e)}
```

--------------------------------

### Get Data with Options

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/realtime_database.md

Retrieves data with advanced options like read timeout, write size limits, shallowing, and complex filtering (orderBy, startAt, etc.).

```cpp
DatabaseOptions options;

options.readTimeout = 5000;

Database.get(aClient, "/path/to/data", options);
```

```cpp
T get(AsyncClientClass &aClient, const String &path, DatabaseOptions &options)
```

--------------------------------

### Get Download Information

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/async_result.md

Retrieves detailed information about a file or BLOB download. Use this to get download status and details.

```cpp
download_data_t downloadInfo() const
```

--------------------------------

### Get Upload Information

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/async_result.md

Retrieves detailed information about a file or BLOB upload. Use this to get upload status and details.

```cpp
upload_data_t uploadInfo() const
```

--------------------------------

### Initialize App and Event Listeners

Source: https://github.com/mobizt/firebaseclient/blob/main/examples/RealtimeDatabase/StreamPerformanceTest/index.html

Sets up the application by initializing Firebase, loading the initial tab, and attaching event listeners to various UI elements for user interaction and configuration changes.

```javascript
function docReady(e){"complete"===document.readyState||"interactive"===document.readyState?setTimeout(e,1):document.addEventListener("DOMContentLoaded",e),addEvent("homeTabLink","click",openTab,"homeTab"),addEvent("setupTabLink","click",openTab,"setupTab"),addEvent("testTabLink","click",openTab,"testTab")}
function saveInterval(){saveConfig("interval"),saveConfig("timeBase"),intvInstant&&authenticated&&(clearIterationLoop(!1),startIterationLoop())}
function saveLedGPIO(){parseInt(getEl("ledGPIO").value)<0&&(getEl("ledGPIO").value="0"),saveChange("ledGPIO")}
function saveDelay(){parseInt(getEl("delayMs").value)<0&&(getEl("delayMs").value="0"),saveChange("delayMs")}
function startIterationLoop(){interval=1e3*parseInt(getEl("interval").value)*("Min"==getEl("timeBase").value?60:1),intvInstant=setInterval((function(){setData(!0)})),interval)}
docReady((function(){addEvent("apiKey","change",saveChange,"apiKey"),addEvent("dbUrl","change",saveChange,"dbUrl"),addEvent("userEmail","change",saveChange,"userEmail"),addEvent("userPsw","change",saveChange,"userPsw"),addEvent("homeTabBtn","click",openTab,"homeTab"),addEvent("setupTabBtn","click",openTab,"setupTab"),addEvent("testTabBtn","click",openTab,"testTab"),addEvent("signInBtn","click",initApp),addEvent("signOutBtn","click",signOutUser),addEvent("mode","click",changeAppendMode),addEvent("path","change",saveChange,"path"),addEvent("valueType","change",saveChange,"valueType"),addEvent("amount","change",saveChange,"amount"),addEvent("interval","change",saveInterval),addEvent("timeBase","change",saveInterval),addEvent("iteration","change",saveChange,"iteration"),addEvent("deviceJob","change",saveDeviceJobs),addEvent("ledGPIO","change",saveLedGPIO),addEvent("delayMs","change",saveDelay),addEvent("enListenerChk","click",addRemoveListener),addEvent("setBtn","click",setDataEvt),addEvent("delBtn","click",delDataEvt),setForm(),loadTab(),initApp()})),document.addEventListener("DOMContentLoaded",(function(){const e=document.querySelectorAll(".navbar-nav .nav-link"),t=document.querySelector(".navbar-collapse");e.forEach((e=>{e.addEventListener("click",(function(){if(document.querySelectorAll(".navbar-nav .nav-link").forEach((e=>{e.classList.remove("text-success-emphasis")})),e.classList.add("text-success-emphasis"),getEl("page").innerHTML=e.innerHTML,t.classList.contains("show")){new bootstrap.Collapse(t,{toggle:!1}).hide()}}))}))}));
```

--------------------------------

### Get Cloud Function

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/cloud_functions.md

Retrieves a specific Cloud Function. This function requires OAuth2.0 authentication. Use FirebaseData.payload() to get the returned payload.

```APIDOC
## void get(AsyncClientClass &aClient, const GoogleCloudFunctions::Parent &parent, const String &functionId, AsyncResultCallback cb, const String &uid = "")

### Description
Retrieves a specific Cloud Function.

### Method
void

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `parent` (GoogleCloudFunctions::Parent) - The GoogleCloudFunctions::Parent object included project Id and location name in its constructor.
- `functionId` (String) - The name of function.
- `cb` (AsyncResultCallback) - The async result callback.
- `uid` (String) - The user specified UID of async result (optional).
```

--------------------------------

### signup (with callback and uid)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firebase_client.md

Signs up a new user with a callback and an optional user ID.

```APIDOC
## signup

### Description
Signup a new user with callback.

### Signature
`static void signup(AsyncClientClass &aClient, FirebaseApp &app, user_auth_data &auth, AsyncResultCallback cb, const String &uid = "")`

### Parameters
- `aClient` (AsyncClientClass &aClient) - The async client to work for authentication/authorization task.
- `app` (FirebaseApp &app) - The FirebaseApp class object to handle authentication/authorization task.
- `auth` (user_auth_data &auth) - The user auth data (`user_auth_data`) which holds the user credentials from `USerAccount` class.
- `cb` (AsyncResultCallback cb) - The async result callback (AsyncResultCallback).
- `uid` (const String &uid = "") - The user specified UID of async result (optional).
```

--------------------------------

### Get ETag from Database Get

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/realtime_database_result.md

Retrieves the ETag associated with a data retrieval operation from the Realtime Database. ETags are used for conditional requests and caching.

```cpp
String ETag() const
```

--------------------------------

### Signup User (with callback)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firebase_client.md

Signs up a new user with Firebase using a callback function to handle the result. Requires an async client, app object, user auth data, and a callback.

```cpp
static void signup(AsyncClientClass &aClient, FirebaseApp &app, user_auth_data &auth, AsyncResultCallback cb, const String &uid = "")
```

--------------------------------

### get(AsyncClientClass &aClient, const Firestore::Parent &parent, AsyncResultCallback cb, const String &uid = "")

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firestore_database.md

Gets information about a database asynchronously using a callback.

```APIDOC
## get(AsyncClientClass &aClient, const Firestore::Parent &parent, AsyncResultCallback cb, const String &uid = "")

### Description
Gets information about a database. The Firebase project Id should be only the name without the firebaseio.com. The Firestore database Id is the Id of database to get the infomation. This function requires ServiceAuth or AccessToken authentication.

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `parent` (Firestore::Parent) - The Firestore::Parent object included project Id and database Id in its constructor.
- `cb` (AsyncResultCallback) - The async result callback (AsyncResultCallback).
- `uid` (String) - The user specified UID of async result (optional).
```

--------------------------------

### Get Release Executable as String

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/rules.md

Retrieve the Release executable for enforcing rules and return it directly as a String. Supports specifying the project, release, and executable version.

```cpp
String getExecutable(AsyncClientClass &aClient, const String &projectId, const String &releaseId, Rules::ReleaseExecutableVersion executableVersion)
```

--------------------------------

### Download Configuration

Source: https://github.com/mobizt/firebaseclient/blob/main/examples/Messaging/WebClient/index.html

Creates a downloadable text file with the provided content. Useful for saving configuration settings.

```javascript
function download(e,t){var a=document.createElement("a");a.setAttribute("href","data:text/plain;charset=utf-8,"+encodeURIComponent(t)),a.setAttribute("download",e),a.style.display="none",document.body.appendChild(a),a.click(),document.body.removeChild(a)}
```

--------------------------------

### Get IAM Policy for a Function (Async)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/cloud_functions.md

Retrieves the IAM policy for a specified Cloud Function asynchronously. Requires OAuth2.0 authentication. Use FirebaseData.payload() to get the returned payload.

```cpp
void getIamPolicy(AsyncClientClass &aClient, const GoogleCloudFunctions::Parent &parent, const String &functionId, GoogleCloudFunctions::GetPolicyOptions options, AsyncResult &aResult)
```

--------------------------------

### AsyncClientClass Constructor with Client and Network Config

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/async_client.md

Initializes an AsyncClientClass with an SSL client and specific network configuration data. The network_config_data can be obtained using static functions from networking classes.

```cpp
AsyncClientClass(Client &client, network_config_data &net)
```

--------------------------------

### Initialize CustomToken from File

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/auth_class.md

Constructs a CustomToken object by loading credentials from a file configuration. The file_config_data object should contain previously saved CustomToken credentials.

```cpp
 explicit CustomToken(const file_config_data &tokenFile)
```

--------------------------------

### Get Firestore Database Information with Callback (Async)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firestore_database.md

Gets information about a database using an asynchronous callback. The Firebase project ID should not include 'firebaseio.com'. This function requires ServiceAuth or AccessToken authentication.

```cpp
void get(AsyncClientClass &aClient, const Firestore::Parent &parent, AsyncResultCallback cb, const String &uid = "")
```

--------------------------------

### Get IAM Policy for a Function (Async with Callback)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/cloud_functions.md

Retrieves the IAM policy for a specified Cloud Function asynchronously using a callback. Requires OAuth2.0 authentication. Use FirebaseData.payload() to get the returned payload.

```cpp
void getIamPolicy(AsyncClientClass &aClient, const GoogleCloudFunctions::Parent &parent, const String &functionId, GoogleCloudFunctions::GetPolicyOptions options, AsyncResultCallback cb, const String &uid = "")
```

--------------------------------

### signup (no callback)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firebase_client.md

Signs up a new user without a callback, using an AsyncResult object.

```APIDOC
## signup

### Description
Signup a new user without callback.

### Signature
`static void signup(AsyncClientClass &aClient, FirebaseApp &app, user_auth_data &auth, AsyncResult &aResult)`

### Parameters
- `aClient` (AsyncClientClass &aClient) - The async client to work for authentication/authorization task.
- `app` (FirebaseApp &app) - The FirebaseApp class object to handle authentication/authorization task.
- `auth` (user_auth_data &auth) - The user auth data (`user_auth_data`) which holds the user credentials from `USerAccount` class.
- `aResult` (AsyncResult &aResult) - The async result (AsyncResult).
```

--------------------------------

### Signup User (with async result)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firebase_client.md

Signs up a new user with Firebase, returning the result via an AsyncResult object. Requires an async client, app object, and user auth data.

```cpp
static void signup(AsyncClientClass &aClient, FirebaseApp &app, user_auth_data &auth, AsyncResult &aResult)
```

--------------------------------

### Get Object Metadata (Synchronous)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/cloud_storage.md

Retrieves metadata for a specific object in a Google Cloud Storage bucket. Requires an async client, parent object with bucket ID and object name, and optional get options.

```cpp
String getMetadata(AsyncClientClass &aClient, const GoogleCloudStorage::Parent &parent, GoogleCloudStorage::GetOptions &options)
```

--------------------------------

### void create(AsyncClientClass &aClient, const String &projectId, const Release &release, AsyncResultCallback cb, const String &uid = "")

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/rules.md

Creates a Ruleset from source. The Ruleset is given a unique generated name. Handles syntactic or semantic errors by indicating the first error encountered.

```APIDOC
## Function: create

### Description
Create a Ruleset from Source. The Ruleset is given a unique generated name which is returned to the caller. Source containing syntactic or semantics errors will result in an error response indicating the first error encountered.

### Signature
```cpp
void create(AsyncClientClass &aClient, const String &projectId, const Release &release, AsyncResultCallback cb, const String &uid = "")
```

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `projectId` (const String&) - The project ID.
- `release` (const Release&) - The Release object.
- `cb` (AsyncResultCallback) - The async result callback.
- `uid` (const String&) - The user specified UID of async result (optional).
```

--------------------------------

### Get a Cloud Function (Asynchronous)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/cloud_functions.md

Initiates an asynchronous request to get details for a specific Cloud Function. The Firebase project ID should not include 'firebaseio.com'. This function requires OAuth2.0 authentication and stores the result in an AsyncResult object.

```cpp
void get(AsyncClientClass &aClient, const GoogleCloudFunctions::Parent &parent, const String &functionId, AsyncResult &aResult)
```

--------------------------------

### Initialize Firebase App (with callback)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firebase_client.md

Initializes the FirebaseApp with an async client, app object, user auth data, and a callback function. An optional user ID can be provided.

```cpp
static void initializeApp(AsyncClientClass &aClient, FirebaseApp &app, user_auth_data &auth, AsyncResultCallback cb, const String &uid = "")
```

--------------------------------

### Signup User (basic)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firebase_client.md

Signs up a new user with Firebase using an async client, app object, and user auth data. This version does not use a callback.

```cpp
static void signup(AsyncClientClass &aClient, FirebaseApp &app, user_auth_data &auth)
```

--------------------------------

### length()

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/async_result.md

Gets the length of the response payload string.

```APIDOC
## length()

### Description
Get the length of response payload string.

### Method
`size_t length() const`

### Returns
- `size_t` - The payload string length.
```

--------------------------------

### Batch Import APNs Tokens (Sync)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/messaging_instance.md

Creates registration tokens for APNs tokens. Specify the application bundle ID, sandbox status, and APNs tokens. Returns the response payload.

```cpp
String batchImport(AsyncClientClass &aClient, const String &application, bool sandbox, const object_t &APNs)
```

--------------------------------

### get()

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/auth_class.md

Retrieves a reference to the internal user authentication data.

```APIDOC
## get()

### Description
Returns the internal user_auth_data reference.

### Returns
- `user_auth_data` - Return internal user_auth_data reference.
```

--------------------------------

### Create RealtimeDatabase Instance

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/realtime_database.md

Creates a new RealtimeDatabase instance with a defined URL. Provide your Firebase database URL.

```cpp
RealtimeDatabase Database("xxxxxxxxx.firebasedatabase.app");
```

--------------------------------

### beginTransaction

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firestore_database.md

Starts a new transaction. Requires ServiceAuth authentication.

```APIDOC
## beginTransaction

### Description
Starts a new transaction. Requires ServiceAuth authentication.

### Method Signature
```cpp
String beginTransaction(AsyncClientClass &aClient, const Firestore::Parent &parent, const TransactionOptions &transOptions)
```

### Parameters
- `aClient` - The async client.
- `parent` - The Firestore::Parent object included project Id and database Id in its constructor.
- `transOptions` - The transaction options.
```

--------------------------------

### ListOptions Configuration

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/rules.md

Configure options for listing ruleset or release instances, including page size, page token, and filtering.

```APIDOC
## ListOptions

### Description
Configuration options for listing ruleset or release instances.

### Methods

#### `pageSize(int value)`
Sets the page size for loading data. The maximum allowed value is 100. Defaults to 10. This is a hint, and the service may return fewer items.

- **Params:**
  - `value` (int) - Optional. The desired page size.

#### `pageToken(const String &value)`
Specifies the next page token for retrieving subsequent batches of Ruleset instances.

- **Params:**
  - `value` (String) - The page token for the next page.

#### `filter(const String value)`
Applies filters to the list method for Ruleset or Release instances.

- **Ruleset Filters:** Supports restrictions on `Ruleset.name`. For time-based filtering, use the `date` function with RFC 3339 compliant strings (e.g., `create_time > date("2017-01-01T00:00:00Z")`). Can be combined with `name` filters (e.g., `name=UUID-*`).
- **Release Filters:** Supports restrictions on `Release.name` and `Release.ruleset_name`. Examples include filtering by a name prefix (e.g., `name=prod*`) or combining name and ruleset name filters (e.g., `name=prod* rulesetName=uuid1234`). Filters are relative to the project, but fully qualified names can also be used.

- **Params:**
  - `value` (String) - Optional. The filter string.
```

--------------------------------

### Get Object Metadata (Asynchronous with Result)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/cloud_storage.md

Asynchronously retrieves metadata for a specific object in a Google Cloud Storage bucket and stores the result in an AsyncResult object. Requires an async client, parent object with bucket ID and object name, and optional get options.

```cpp
void getMetadata(AsyncClientClass &aClient, const GoogleCloudStorage::Parent &parent, GoogleCloudStorage::GetOptions &options, AsyncResult &aResult)
```

--------------------------------

### LegacyToken Constructor (file_config_data)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/auth_class.md

Initializes LegacyToken using filesystem data for custom token credentials.

```APIDOC
## LegacyToken(const file_config_data &tokenFile)

### Description
A LegacyToken constructor.

### Parameters
#### Path Parameters
- **tokenFile** (file_config_data) - Required - The filesystem data (`file_config_data`) obtained from `FileConfig` class object of file that the `CustomToken` credentials will be saved to or read from.
```

--------------------------------

### RealtimeDatabase Constructor

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/realtime_database.md

Creates a new RealtimeDatabase instance with a defined URL.

```APIDOC
## RealtimeDatabase(const String &url = "")

### Description
Create new RealtimeDatabase instance with defined url.

### Example
```cpp
RealtimeDatabase Database("xxxxxxxxx.firebasedatabase.app");
```

### Signature
```cpp
RealtimeDatabase(const String &url = "")
```

### Parameters
* `url` (String) - The database url
```

--------------------------------

### Get Object Metadata (Asynchronous with Callback)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/cloud_storage.md

Asynchronously retrieves metadata for a specific object in a Google Cloud Storage bucket using a callback function. Requires an async client, parent object with bucket ID and object name, optional get options, and a callback function.

```cpp
void getMetadata(AsyncClientClass &aClient, const GoogleCloudStorage::Parent &parent, GoogleCloudStorage::GetOptions &options, AsyncResultCallback cb, const String &uid = "")
```

--------------------------------

### Download Object with Options

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/cloud_storage.md

Downloads an object from a Google Cloud Storage bucket. The `options` parameter allows for customization of the download process via API parameters.

```cpp
bool download(AsyncClientClass &aClient, const GoogleCloudStorage::Parent &parent, file_config_data &file, GoogleCloudStorage::GetOptions &options)
```

--------------------------------

### Get C-String Pointer

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/placeholders.md

Returns a pointer to the internal string buffer.

```APIDOC
## c_str()

### Description
Return the pointer to internal string buffer.

### Method
c_str

### Returns
- `const char *` - The pointer to internal string buffer.
```

--------------------------------

### Perform OTA Update with Callback

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/realtime_database.md

Initiates an OTA update using a firmware file from the database. The firmware data should be a base64 encoded string. This version uses a callback for asynchronous results.

```cpp
Database.ota(aClient, "/path/to/data", cb, U_FLASH);
```

--------------------------------

### Initialize CustomAuth with Service Account Details

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/auth_class.md

Use this constructor when you have the service account credentials (API key, client email, project ID, private key) and user ID readily available. It also supports optional custom claims and an expiration time for the token.

```cpp
explicit CustomAuth(TimeStatusCallback timeCb, const String &apiKey, const String &clientEmail, const String &projectId, const String &privateKey, const String &uid, const String &claims = "", size_t expire = FIREBASE_DEFAULT_TOKEN_TTL)
```

--------------------------------

### ttl

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firebase_app.md

Gets the remaining time in seconds until the current token expires.

```APIDOC
## ttl()

### Description
Get the remaining time to live of token until expired.

### Returns
- `unsigned long` - The integer value of ttl.
```

--------------------------------

### Initialize IDToken from File

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/auth_class.md

Constructs an IDToken object by loading credentials from a file configuration. The file_config_data object should contain previously saved IDToken credentials.

```cpp
 explicit IDToken(const file_config_data &tokenFile)
```

--------------------------------

### RealtimeDatabase Destructor

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/realtime_database.md

Destructor for the RealtimeDatabase class. No parameters or setup required.

```cpp
~RealtimeDatabase()
```

--------------------------------

### String create(AsyncClientClass &aClient, const String &projectId, const Release &release)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/rules.md

Creates a Ruleset from source and returns the generated name as a String. Handles syntactic or semantic errors by indicating the first error encountered.

```APIDOC
## Function: create

### Description
Create a Ruleset from Source. The Ruleset is given a unique generated name which is returned to the caller. Source containing syntactic or semantics errors will result in an error response indicating the first error encountered.

### Signature
```cpp
String create(AsyncClientClass &aClient, const String &projectId, const Release &release)
```

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `projectId` (const String&) - The project ID.
- `release` (const Release&) - The Release object.

### Returns
- `String` - The response payload.
```

--------------------------------

### Get Request Path

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/async_result.md

Retrieves the path of the resource that was requested. This can be helpful for logging or routing.

```cpp
String path() const
```

--------------------------------

### void get(AsyncClientClass &aClient, const String &path, file_config_data &file, AsyncResult &aResult)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/realtime_database.md

Retrieves data from a specified node path in the Realtime Database. It utilizes file system configurations for handling data operations.

```APIDOC
## void get(AsyncClientClass &aClient, const String &path, file_config_data &file, AsyncResult &aResult)

### Description
Get value at the node path. The FileConfig object constructor should be included filename and FileConfigCallback.

The FileConfigCallback function contains the parameters i.e., File reference returned from file operation, filename for file operation and file_operating_mode.

### Parameters
- `aClient` - The async client.
- `path` - The node path to get value.
- `file` - The filesystem data (file_config_data) obtained from FileConfig class object.
- `aResult` - The async result (AsyncResult)
```

--------------------------------

### Begin Transaction (AsyncResultCallback)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firestore_database.md

Starts a new transaction asynchronously, with results delivered to a callback function. Requires ServiceAuth authentication. The Firebase project ID should be the name without 'firebaseio.com'. Transaction options can be configured for read-only or read-write modes.

```cpp
void beginTransaction(AsyncClientClass &aClient, const Firestore::Parent &parent, const TransactionOptions &transOptions, AsyncResultCallback cb, const String &uid = "")
```

--------------------------------

### void create(AsyncClientClass &aClient, const String &projectId, const Release &release, AsyncResult &aResult)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/rules.md

Creates a Ruleset from source, storing the result in an AsyncResult object. Handles syntactic or semantic errors by indicating the first error encountered.

```APIDOC
## Function: create

### Description
Create a Ruleset from Source. The Ruleset is given a unique generated name which is returned to the caller. Source containing syntactic or semantics errors will result in an error response indicating the first error encountered.

### Signature
```cpp
void create(AsyncClientClass &aClient, const String &projectId, const Release &release, AsyncResult &aResult)
```

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `projectId` (const String&) - The project ID.
- `release` (const Release&) - The Release object.
- `aResult` (AsyncResult&) - The async result.
```

--------------------------------

### get (String)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firestore_database.md

Retrieves a composite index and returns it as a string. This function requires ServiceAuth authentication.

```APIDOC
## get (String)

### Description
Gets a composite index.

### Parameters
- `aClient` (AsyncClientClass &) - The async client.
- `parent` (const Firestore::Parent &) - The Firestore::Parent object included project Id and database Id in its constructor.
- `collectionId` (const String &) - The collection Id.
- `indexId` (const String &) - The index to get.

### Returns
- `String` - The response payload.
```

--------------------------------

### void get(AsyncClientClass &aClient, const String &path, file_config_data &file, AsyncResultCallback cb, const String &uid = "")

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/realtime_database.md

Retrieves data from a specified node path in the Realtime Database, with a callback for asynchronous result handling. It also supports an optional user-defined ID for the result.

```APIDOC
## void get(AsyncClientClass &aClient, const String &path, file_config_data &file, AsyncResultCallback cb, const String &uid = "")

### Description
Get value at the node path. The FileConfig object constructor should be included filename and FileConfigCallback.

The FileConfigCallback function contains the parameters i.e., File reference returned from file operation, filename for file operation and file_operating_mode.

### Parameters
- `aClient` - The async client.
- `path` - The node path to get value.
- `file` - The filesystem data (file_config_data) obtained from FileConfig class object.
- `cb` - The async result callback (AsyncResultCallback).
- `uid` - The user specified UID of async result (optional).
```

--------------------------------

### get (String)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firestore_database.md

Retrieves an index and returns the response payload as a String. Requires ServiceAuth authentication.

```APIDOC
## get (String)

### Description
Gets an index and returns the response payload.

### Method
```cpp
String get(AsyncClientClass &aClient, const Firestore::Parent &parent, const String &indexId)
```

### Parameters
- `aClient` - The async client.
- `parent` - The Firestore::Parent object included project Id and database Id in its constructor.
- `indexId` - The index to get.

### Returns
- `String` - The response payload.
```

--------------------------------

### Get App Instance Information (Callback)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/messaging_instance.md

Retrieve information about a specific app instance using its instance ID token and a callback function. An optional user-specified UID can be provided for the async result.

```cpp
void get(AsyncClientClass &aClient, const String &IID, AsyncResultCallback cb, const String &uid = "")
```

--------------------------------

### Get Release with Callback

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/rules.md

Retrieves a Release by its name using an asynchronous client and a callback for results.

```cpp
void get(AsyncClientClass &aClient, const String &projectId, const String &releaseId, AsyncResultCallback cb, const String &uid = "")
```

--------------------------------

### Get User Authentication Data

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/auth_class.md

Retrieves a reference to the internal user authentication data structure.

```cpp
user_auth_data &get()
```

--------------------------------

### Initialize FirebaseApp with User Authentication

Source: https://context7.com/mobizt/firebaseclient/llms.txt

Use this snippet for user authentication with email and password. Ensure required build options are enabled and call `app.loop()` in your main loop to maintain authentication.

```cpp
#define ENABLE_USER_AUTH
#define ENABLE_DATABASE
#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <FirebaseClient.h>

// User authentication with email/password
UserAuth user_auth("WEB_API_KEY", "user@example.com", "password123", 3300);

FirebaseApp app;
WiFiClientSecure ssl_client;
using AsyncClient = AsyncClientClass;
AsyncClient aClient(ssl_client);
RealtimeDatabase Database;

void authCallback(AsyncResult &aResult) {
    if (aResult.isDebug())
        Firebase.printf("Auth debug: %s\n", aResult.debug().c_str());
    if (aResult.isError())
        Firebase.printf("Auth error: %s, code: %d\n", aResult.error().message().c_str(), aResult.error().code());
}

void setup() {
    WiFi.begin("SSID", "PASSWORD");
    while (WiFi.status() != WL_CONNECTED) delay(300);

    ssl_client.setInsecure(); // or set CA cert for production

    // Async auth init with callback
    initializeApp(aClient, app, getAuth(user_auth), authCallback, "authTask");

    // Bind the authenticated app to the service class
    app.getApp<RealtimeDatabase>(Database);
    Database.url("PROJECT-ID-default-rtdb.firebaseio.com");
}

void loop() {
    app.loop(); // Maintains auth tokens and async task queue
    // ...
}
```

--------------------------------

### AsyncClientClass(Client &client, network_config_data &net)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/async_client.md

Constructor that takes a reference to a Client object and network configuration data.

```APIDOC
## AsyncClientClass(Client &client, network_config_data &net)

### Description
Initializes the AsyncClientClass with a given SSL client and specific network configuration data.

### Method
Constructor

### Parameters
#### Path Parameters
- **client** (Client&) - The SSL client that working with the network interface.
- **net** (network_config_data&) - The network config data can be obtained from the networking classes via the static function called `getNetwork`.

### Code
```cpp
AsyncClientClass(Client &client, network_config_data &net)
```
```

--------------------------------

### Get Task Count

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/async_client.md

Retrieve the number of asynchronous and synchronous tasks currently stored in the queue.

```cpp
size_t taskCount() const
```

--------------------------------

### Get Debug Information

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/async_result.md

Retrieves detailed debug information about the asynchronous operation. Use this for troubleshooting.

```cpp
String debug()
```

--------------------------------

### Initialize Placeholder as JSON Array (C++)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/placeholders.md

Initializes the placeholder to represent a JSON array.

```cpp
void initArray()
```

--------------------------------

### create(AsyncClientClass &aClient, const String &projectId, const Ruleset &ruleSet, AsyncResultCallback cb, const String &uid = "")

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/rules.md

Create a Ruleset from Source. The Ruleset is given a unique generated name which is returned to the caller. Source containing syntactic or semantics errors will result in an error response indicating the first error encountered.

```APIDOC
## void create(AsyncClientClass &aClient, const String &projectId, const Ruleset &ruleSet, AsyncResultCallback cb, const String &uid = "")

### Description
Create a Ruleset from Source. The Ruleset is given a unique generated name which is returned to the caller. Source containing syntactic or semantics errors will result in an error response indicating the first error encountered.

### Signature
```cpp
void create(AsyncClientClass &aClient, const String &projectId, const Ruleset &ruleSet, AsyncResultCallback cb, const String &uid = "")
```

### Parameters
#### Path Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `projectId` (const String&) - The project ID.
- `ruleSet` (const Ruleset&) - The ruleset object.
- `cb` (AsyncResultCallback) - The async result callback.
- `uid` (const String&) - The user specified UID of async result (optional).
```

--------------------------------

### get (AsyncResult)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firestore_database.md

Retrieves an index asynchronously and stores the result in an AsyncResult object. Requires ServiceAuth authentication.

```APIDOC
## get (AsyncResult)

### Description
Gets an index asynchronously.

### Method
```cpp
void get(AsyncClientClass &aClient, const Firestore::Parent &parent, const String &indexId, AsyncResult &aResult)
```

### Parameters
- `aClient` - The async client.
- `parent` - The Firestore::Parent object included project Id and database Id in its constructor.
- `indexId` - The index to get.
- `aResult` - The async result (AsyncResult).
```

--------------------------------

### Get Metadata (AsyncResult)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/storage.md

Retrieves the metadata for a specified object in Firebase Storage and stores it in an AsyncResult object.

```APIDOC
## getMetadata (AsyncResult)

### Description
Retrieves the metadata for a specified object in Firebase Storage, storing the result in an AsyncResult object.

### Signature
```cpp
void getMetadata(AsyncClientClass &aClient, const FirebaseStorage::Parent &parent, AsyncResult &aResult)
```

### Parameters
- `aClient` (AsyncClientClass&) - The async client.
- `parent` (FirebaseStorage::Parent&) - The FirebaseStorage::Parent object included Storage bucket Id and object in its constructor.
- `aResult` (AsyncResult&) - The async result object to store the metadata.
```

--------------------------------

### Static FileConfig::getBlob Method

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/file_config.md

A static utility function to get the reference of file_config_data from a BlobConfig object.

```cpp
static file_config_data &getBlob(BlobConfig &blob)
```

--------------------------------

### FirebaseClient Library Build Options

Source: https://github.com/mobizt/firebaseclient/blob/main/README.md

List of available preprocessor macros to enable specific features of the FirebaseClient library. Define these before including the library header or as compiler build flags.

```cpp
ENABLE_DATABASE // For RTDB compilation
ENABLE_FIRESTORE // For Firestore compilation
ENABLE_FIRESTORE_QUERY // For Firestore Query feature compilation
ENABLE_MESSAGING // For Firebase Cloud Messaging compilation
ENABLE_STORAGE // For Firebase Storage compilation
ENABLE_CLOUD_STORAGE // For Google Cloud Storage compilation
ENABLE_FUNCTIONS // For Google Cloud Functions compilation
ENABLE_RULESETS // For RuleSets compilation
ENABLE_PSRAM // For enabling PSRAM support
ENABLE_OTA // For enabling OTA updates support
ENABLE_FS // For enabling Flash filesystem support

FIREBASE_ASYNC_QUEUE_LIMIT // For maximum async queue limit (number).
FIREBASE_PRINTF_PORT // For Firebase.printf debug port class object.
FIREBASE_PRINTF_BUFFER // Firebase.printf buffer size.

// For enabling authentication and token
ENABLE_SERVICE_AUTH
ENABLE_CUSTOM_AUTH
ENABLE_USER_AUTH
ENABLE_ACCESS_TOKEN
ENABLE_CUSTOM_TOKEN
ENABLE_ID_TOKEN
ENABLE_LEGACY_TOKEN

```

--------------------------------

### Initialize as JSON Array

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/placeholders.md

Initiates the placeholder to represent a JSON array.

```APIDOC
## initArray()

### Description
Initiates the placeholder as JSON Array object representation.

### Method
initArray

### Returns
- `void`
```

--------------------------------

### Static FileConfig::getFile Method

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/file_config.md

A static utility function to get the reference of file_config_data from a FileConfig object.

```cpp
static file_config_data &getFile(FileConfig &file)
```

--------------------------------

### Initialize Firebase App (with timeout)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firebase_client.md

Initializes the FirebaseApp with an async client, app object, and user auth data. Supports an optional timeout and callback.

```cpp
static void initializeApp(AsyncClientClass &aClient, FirebaseApp &app, user_auth_data &auth, unsigned long timeoutMs = 0, AsyncResultCallback cb = NULL)
```

--------------------------------

### Get ETag Header

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/async_result.md

Retrieves the ETag from the server response headers. This is often used for caching validation.

```cpp
String etag() const
```

--------------------------------

### get (void, AsyncResultCallback)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firestore_database.md

Retrieves a composite index using an asynchronous callback. This function requires ServiceAuth authentication.

```APIDOC
## get (void, AsyncResultCallback)

### Description
Gets a composite index.

### Parameters
- `aClient` (AsyncClientClass &) - The async client.
- `parent` (const Firestore::Parent &) - The Firestore::Parent object included project Id and database Id in its constructor.
- `collectionId` (const String &) - The collection Id.
- `indexId` (const String &) - The index to get.
- `cb` (AsyncResultCallback) - The async result callback (AsyncResultCallback).
- `uid` (const String &) - The user specified UID of async result (optional).
```

--------------------------------

### Initialize Placeholder as JSON Object (C++)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/placeholders.md

Initializes the placeholder to represent a JSON object.

```cpp
void initObject()
```

--------------------------------

### get (Callback)

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/firestore_database.md

Retrieves an index asynchronously and invokes a callback function upon completion. Requires ServiceAuth authentication.

```APIDOC
## get (Callback)

### Description
Gets an index asynchronously with a callback.

### Method
```cpp
void get(AsyncClientClass &aClient, const Firestore::Parent &parent, const String &indexId, AsyncResultCallback cb, const String &uid = "")
```

### Parameters
- `aClient` - The async client.
- `parent` - The Firestore::Parent object included project Id and database Id in its constructor.
- `indexId` - The index to get.
- `cb` - The async result callback (AsyncResultCallback).
- `uid` - The user specified UID of async result (optional).
```

--------------------------------

### Get Release with AsyncResult

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/rules.md

Retrieves a Release by its name using an asynchronous client and an AsyncResult object to store the outcome.

```cpp
void get(AsyncClientClass &aClient, const String &projectId, const String &releaseId, AsyncResult &aResult)
```

--------------------------------

### Initialize as JSON Object

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/placeholders.md

Initiates the placeholder to represent a JSON object.

```APIDOC
## initObject()

### Description
Initiates the placeholder as JSON object representation.

### Method
initObject

### Returns
- `void`
```

--------------------------------

### Perform OTA Update with AsyncResult

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/realtime_database.md

Initiates an OTA update using a firmware file from the database. The firmware data should be a base64 encoded string. This version uses an AsyncResult object to capture the outcome.

```cpp
Database.ota(aClient, "/path/to/data", aResult, U_FLASH);
```

--------------------------------

### Firestore::Documents::batchGet

Source: https://context7.com/mobizt/firebaseclient/llms.txt

Retrieves multiple Firestore documents in a single request using a batch get operation.

```APIDOC
## Firestore::Documents::batchGet — Fetch Multiple Documents

### Description
Retrieves multiple documents in a single request.

### Method
`batchGet`

### Parameters
- `aClient`: The Firebase client instance.
- `parent`: The parent document path.
- `batchOpts`: `BatchGetDocumentOptions` specifying documents to retrieve and optional field mask.

### Request Example
```cpp
BatchGetDocumentOptions batchOpts;
batchOpts.addDocument("projects/my-project-id/databases/(default)/documents/sensors/s1");
batchOpts.addDocument("projects/my-project-id/databases/(default)/documents/sensors/s2");
batchOpts.mask("temperature,sensorId"); // optional field mask

String result = Docs.batchGet(aClient, Firestore::Parent("my-project-id"), batchOpts);
if (aClient.lastError().code() == 0)
    Serial.println(result); // array of found/missing documents
```

### Response
- Returns a JSON string representing an array of found and missing documents.
```

--------------------------------

### Get Boolean as C-String

Source: https://github.com/mobizt/firebaseclient/blob/main/resources/docs/placeholders.md

Returns a pointer to the internal string representation of the boolean value. Useful for logging or debugging.

```cpp
const char * c_str() const
```