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### Run ext:migrate to start migration

Source: https://firebase.google.com/docs/extensions/users/migrate

Starts an interactive migration for an extension instance. The command guides you through selecting an extension, updating it, installing and deploying the function kit, and uninstalling the extension.

```bash
firebase ext:migrate --project <project-id>
```

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

### Start the development server

Source: https://firebase.google.com/docs/sql-connect/quickstart/react

Run this command to start the development server and see the example app in action.

```shell
npm run dev
```

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

### Example: Get details for a specific Remote Config experiment

Source: https://firebase.google.com/docs/remote-config/automate-rc

Example command to get details for the experiment with ID exp_promo_discount_2026.

```bash
firebase remoteconfig:experiments:get exp_promo_discount_2026
```

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

### Complete example

Source: https://firebase.google.com/docs/functions/oncallgenkit

After you've made all of the changes described in this guide, your deployable flow will look something like the following example:

```javascript
const {onCallGenkit} = require("firebase-functions/https");
const {defineSecret} = require("firebase-functions/params");

// Dependencies for Genkit.
const {gemini15Flash, googleAI} = require("@genkit-ai/googleai");
const {genkit, z} = require("genkit");

// Store the Gemini API key in Cloud Secret Manager.
const apiKey = defineSecret("GOOGLE_GENAI_API_KEY");

const ai = genkit({
  plugins: [googleAI()],
  model: gemini15Flash,
});

const jokeTeller = ai.defineFlow({
  name: "jokeTeller",
  inputSchema: z.string().nullable(),
  outputSchema: z.string(),
  streamSchema: z.string(),
}, async (jokeType = "knock-knock", {sendChunk}) => {
  const prompt = `Tell me a ${jokeType} joke.`;

  // Call the `generateStream()` method to
  // receive the `stream` async iterable.
  const {stream, response: aiResponse} = ai.generateStream(prompt);

  // Send new words of the generative AI response
  // to the client as they are generated.
  for await (const chunk of stream) {
    sendChunk(chunk.text);
  }

  // Return the full generative AI response
  // to clients that may not support streaming.
  return (await aiResponse).text;
},
);

exports.tellJoke = onCallGenkit({
  // Bind the Gemini API key secret parameter to the function.
  secrets: [apiKey],
},
// Pass in the genkit flow.
jokeTeller,
);index.js
```

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

### Example: Get details for a specific Remote Config rollout

Source: https://firebase.google.com/docs/remote-config/automate-rc

Example command to get details for the rollout with ID rollout_new_checkout_flow.

```bash
firebase remoteconfig:rollouts:get rollout_new_checkout_flow
```

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

### Example package.json file

Source: https://firebase.google.com/docs/web/module-bundling

This is an example of the package.json file generated by npm init. The dependencies object will list installed libraries and their versions.

```json
{
  "name": "your-package-name",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {

  }
}
```

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

### Swift: Add a simple cursor to a query using startAt

Source: https://firebase.google.com/docs/firestore/query-data/query-cursors

Use the start(at:) method to define the start point for a query, including the start point. This example gets all cities with population over one million, ordered by population.

```swift
// Get all cities with population over one million, ordered by population.
db.collection("cities")
  .order(by: "population")
  .start(at: [1000000])
```

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

### Set up Emulator Suite

Source: https://firebase.google.com/docs/emulator-suite/install_and_configure

Run this command to start a configuration wizard that lets you select emulators of interest, download the corresponding emulator binary files, and set emulator ports if the defaults are not appropriate.

```shell
firebase init emulators
```

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

### substring usage example (fieldName, index, length)

Source: https://firebase.google.com/docs/reference/kotlin/com/google/firebase/firestore/pipeline/Expression

Gets a substring of the 'message' field starting at index 5 with length 10.

```kotlin
// Get a substring of the 'message' field starting at index 5 with length 10.
substring("message", 5, 10)
```

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

### Example

Source: https://firebase.google.com/docs/studio/devnix-reference

Example of configuring IDX previews in a Nix configuration.

```nix
{pkgs, ...}: {
  idx.previews = {
    enable = true;
    previews = {
      web = {
        command = ["yes"];
        cwd = "subfolder";
        manager = "web";
        env = {
          HELLO = "world";
        };
      };
    };
  };
}
```

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

### Example PREINSTALL.md content

Source: https://firebase.google.com/docs/extensions/publishers/get-started

Use this example as a template for your extension's PREINSTALL.md file. It describes the extension's purpose, expected database layout, additional setup, and billing implications.

```markdown
Use this extension to automatically convert strings to upper case when added to
a specified Realtime Database path.

This extension expects a database layout like the following example:

    "messages": {
      MESSAGE_ID: {
        "original": MESSAGE_TEXT
      },
      MESSAGE_ID: {
        "original": MESSAGE_TEXT
      },
    }

When you create new string records, this extension creates a new sibling record
with upper-cased text:

    MESSAGE_ID: {
      "original": MESSAGE_TEXT,
      "upper": UPPERCASE_MESSAGE_TEXT,
    }

#### Additional setup

Before installing this extension, make sure that you've
[set up Realtime Database](https://firebase.google.com/docs/database/quickstart)
in your Firebase project.

#### Billing

To install an extension, your project must be on the
[Blaze (pay as you go) plan](https://firebase.google.com/pricing).

- This extension uses other Firebase and Google Cloud Platform services, which
  have associated charges if you exceed the service's no-cost tier:
  - Realtime Database
  - Cloud Functions (Node.js 10+ runtime)
    [See FAQs](/docs/functions/faq-and-troubleshooting#extensions-pricing)
- If you enable events,
  [Eventarc fees apply](https://cloud.google.com/eventarc/pricing).
```

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

### C++: Add a simple cursor to a query using startAt

Source: https://firebase.google.com/docs/firestore/query-data/query-cursors

Use the StartAt() method to define the start point for a query, including the start point. This example gets all cities with a population >= 1,000,000, ordered by population.

```cpp
// Get all cities with a population >= 1,000,000, ordered by population,
db->Collection("cities")
    .OrderBy("population")
    .StartAt({FieldValue::Integer(1000000)});
```

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

### Java: Add a simple cursor to a query using startAt

Source: https://firebase.google.com/docs/firestore/query-data/query-cursors

Use the startAt() method to define the start point for a query, including the start point. This example gets all cities with a population >= 1,000,000, ordered by population.

```java
// Get all cities with a population >= 1,000,000, ordered by population,
db.collection("cities")
        .orderBy("population")
        .startAt(1000000);
```

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

### Example POSTINSTALL.md content

Source: https://firebase.google.com/docs/extensions/publishers/get-started

Use this example as a template for your extension's POSTINSTALL.md file. It shows how to guide users to test the extension, use it effectively, and monitor its activity.

```markdown
### See it in action

You can test out this extension right away!

1.  Go to your
    [Realtime Database dashboard](https://console.firebase.google.com/project/${param:PROJECT_ID}/database/${param:PROJECT_ID}/data) in the Firebase console.

1.  Add a message string to a path that matches the pattern `${param:MESSAGE_PATH}`.

1.  In a few seconds, you'll see a sibling node named `upper` that contains the
    message in upper case.

### Using the extension

We recommend adding data by pushing -- for example,
`firebase.database().ref().push()` -- because pushing assigns an automatically
generated ID to the node in the database. During retrieval, these nodes are
guaranteed to be ordered by the time they were added. Learn more about reading
and writing data for your platform (iOS, Android, or Web) in the
[Realtime Database documentation](https://firebase.google.com/docs/database/).

### Monitoring

As a best practice, you can
[monitor the activity](https://firebase.google.com/docs/extensions/manage-installed-extensions#monitor)
of your installed extension, including checks on its health, usage, and logs.
```

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

### Kotlin: Add a simple cursor to a query using startAt

Source: https://firebase.google.com/docs/firestore/query-data/query-cursors

Use the startAt() method to define the start point for a query, including the start point. This example gets all cities with a population >= 1,000,000, ordered by population.

```kotlin
// Get all cities with a population >= 1,000,000, ordered by population,
db.collection("cities")
    .orderBy("population")
    .startAt(1000000)
```

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

### Example dev.nix configuration with packages and channel

Source: https://firebase.google.com/docs/studio/devnix-reference

Example showing how to specify a channel and install packages in the dev.nix file. The pkgs argument is used to select packages, and its contents depend on the selected channel.

```nix
{pkgs, ...}: {
  channel = "stable-24.11";
  packages = [pkgs.vim];
}
```

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

### Objective-C: Add a simple cursor to a query using startAt

Source: https://firebase.google.com/docs/firestore/query-data/query-cursors

Use the queryStartingAtValues: method to define the start point for a query, including the start point. This example gets all cities with population over one million, ordered by population.

```objective-c
// Get all cities with population over one million, ordered by population.
[[[db collectionWithPath:@"cities"]
    queryOrderedByField:@"population"]
    queryStartingAtValues:@[ @1000000 ]];
```

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

### AI prompt for Firebase Crashlytics setup assistance

Source: https://firebase.google.com/docs/crashlytics/android/get-started

Copy this prompt into an AI coding agent to get help setting up Firebase Crashlytics. It instructs the agent to install Firebase agent skills and then assist with Crashlytics setup.

```text
Help me use Firebase in my app.
1. Make sure that **Firebase agent skills** are installed and updated. For Claude Code, Codex, or Cursor agents, help me install the Firebase plugin. For other agents, run `npx skills add firebase/agent-skills`. Always try to use **Firebase agent skills** for Firebase-related tasks.
2. Help me set up Firebase Crashlytics for my app.
```

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

### Node.js: Set up sample documents for collection stage example

Source: https://firebase.google.com/docs/firestore/pipelines/stages/input/collection

Creates sample documents in the `cities` and `states` collections to demonstrate the `collection` stage.

```javascript
await db.collection("cities").doc("SF").set({name: "San Francsico", state: "California"});
await db.collection("cities").doc("NYC").set({name: "New York City", state: "New York"});
await db.collection("cities").doc("CHI").set({name: "Chicago", state: "Illinois"});
await db.collection("states").doc("CA").set({name: "California"});
```

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

### substring usage example (Expression, Expression, Expression)

Source: https://firebase.google.com/docs/reference/kotlin/com/google/firebase/firestore/pipeline/Expression

Gets a substring of the 'message' field starting at index 5 with length 10 using expressions.

```kotlin
// Get a substring of the 'message' field starting at index 5 with length 10.
substring(field("message"), constant(5), constant(10))
```

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

### Example: List Remote Config rollouts

Source: https://firebase.google.com/docs/remote-config/automate-rc

Example command to list all Remote Config rollouts for the project.

```bash
firebase remoteconfig:rollouts:list
```

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

### Example

Source: https://firebase.google.com/docs/studio/devnix-reference

Example of setting environment variables in a Nix configuration.

```nix
{pkgs, ...}: {
  env = {
    HELLO = "world";
    # append an entry to PATH
    PATH = ["/some/path/bin"];
  };
}
```

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

### arraySlice(offset: Expression): Slice array from expression offset

Source: https://firebase.google.com/docs/reference/swift/firebasefirestore/api/reference/Protocols/Expression

Returns a subset of the array starting at the given offset. Assumes `self` evaluates to an array. The example gets all elements from "tags" starting at an offset defined by a field.

```swift
// Get all elements from "tags" starting at an offset defined by a field
Field("tags").arraySlice(offset: Field("startIdx"))
```

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

### Example entry point file src/index.js

Source: https://firebase.google.com/docs/web/module-bundling

This file is the entry point because it imports other modules. Module bundlers start bundling from this file.

```javascript
// src/index.js
import { animate } from './animations';
import { createList } from './datalist';

// This is not real code, but for example purposes only
const theList = createList('users/123/tasks');
theList.addEventListener('loaded', event => {
  animate(theList);
});
```

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

### arraySlice(offset: Int): Slice array from integer offset

Source: https://firebase.google.com/docs/reference/swift/firebasefirestore/api/reference/Protocols/Expression

Returns a subset of the array starting at the given offset. Assumes `self` evaluates to an array. The example gets all elements from the "tags" array starting at index 1.

```swift
// Get all elements from the "tags" array starting at index 1
Field("tags").arraySlice(offset: 1)
```

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

### Create a new directory for Go sample

Source: https://firebase.google.com/docs/hosting/cloud-run

Create a new directory named helloworld-go and change into it.

```shell
mkdir helloworld-go
```

```shell
cd helloworld-go
```

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

### Set inference mode to PREFER_ON_DEVICE

Source: https://firebase.google.com/docs/ai-logic/hybrid/web/configuration-options

Use the on-device model if available; otherwise fall back to the cloud-hosted model. This is the default mode used in the getting started guide.

```javascript
const model = getGenerativeModel(ai, { mode: InferenceMode.PREFER_ON_DEVICE });
```

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

### AI prompt for Firebase App Hosting setup

Source: https://firebase.google.com/docs/app-hosting/get-started

Copy this prompt into an AI coding agent to get help with installing Firebase agent skills and hosting your web app.

```text
Help me use Firebase in my app.
1. Make sure that **Firebase agent skills** are installed and updated. For Claude Code, Codex, or Cursor agents, help me install the Firebase plugin. For other agents, run `npx skills add firebase/agent-skills`.  Always try to use **Firebase agent skills** for Firebase-related tasks.
2. Help me use Firebase to host my web app. Set up my app to use Firebase, and then deploy my app.
```

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

### Set up sample documents in Node.js

Source: https://firebase.google.com/docs/firestore/pipelines/stages/input/database

Creates three documents in the cities, states, and countries collections. These documents are used in the subsequent database() stage example to demonstrate retrieving all documents.

```javascript
await db.collection("cities").doc("SF").set({name: "San Francsico", state: "California", population: 800000});
await db.collection("states").doc("CA").set({name: "California", population: 39000000});
await db.collection("countries").doc("USA").set({name: "United States of America", population: 340000000});
```

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

### Configure workspace onCreate with npm install and openFiles

Source: https://firebase.google.com/docs/studio/devnix-reference

Use idx.workspace.onCreate to run commands when the workspace is first created and opened. The example runs npm install and opens src/index.ts.

```nix
{pkgs, ...}: {
  idx.workspace.onCreate = {
    npm-install = "npm install";
    # files to open when the workspace is first opened.
    default.openFiles = [ "src/index.ts" ];
  };
}
```

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

### Worked example: List extensions for my-project

Source: https://firebase.google.com/docs/extensions/migration-best-practices

Example of listing extensions for a project named my-project.

```bash
firebase ext:list --project my-project
```

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

### AI prompt for Firestore Enterprise setup assistance

Source: https://firebase.google.com/docs/firestore/enterprise/quickstart

Copy this prompt into an AI coding agent to get help setting up Firestore Enterprise edition and choosing a database location. Requires Firebase agent skills to be installed.

```text
Help me use Firebase in my app.
1. Make sure that **Firebase agent skills** are installed and updated. For Claude Code, Codex, or Cursor agents, help me install the Firebase plugin. For other agents, run `npx skills add firebase/agent-skills`. Always try to use **Firebase agent skills** for Firebase-related tasks.
2. Help me set up and use Firebase for the backend of my app. Set up Firestore database in **Enterprise edition**. Help me to choose the best location for my database instance.
```

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

### Create sample restaurant and review documents in Node.js

Source: https://firebase.google.com/docs/firestore/pipelines/stages/input/subcollection

Set up sample data with three restaurants and their reviews. This data is used in the subsequent query example.

```javascript
const restaurant1 = db.collection("restaurants").document("pizza-place");
const restaurant2 = db.collection("restaurants").document("urban-bite");
const restaurant3 = db.collection("restaurants").document("nacho-house");

await restaurant1.create({ name: "Pizza Place" });
await restaurant2.create({ name: "Urban Bite" });
await restaurant3.create({ name: "Nacho House" });

await restaurant1.collection("reviews").doc("1").create({ rating: 5 });
await restaurant1.collection("reviews").doc("1").create({ rating: 2 });

await restaurant2.collection("reviews").doc("1").create({ rating: 3 });
await restaurant2.collection("reviews").doc("1").create({ rating: 4 });
await restaurant2.collection("reviews").doc("1").create({ rating: 5 });
```

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

### AI prompt for Firebase Authentication setup

Source: https://firebase.google.com/docs/auth/flutter/password-auth

Copy this prompt into an AI coding agent to get help setting up Firebase Authentication with email and password. It instructs the agent to install Firebase agent skills and assist with configuration.

```text
Help me use Firebase in my app.
1. Make sure that **Firebase agent skills** are installed and updated. For Claude Code, Codex, or Cursor agents, help me install the Firebase plugin. For other agents, run `npx skills add firebase/agent-skills`. Always try to use **Firebase agent skills** for Firebase-related tasks.
2. Help me set up and use Firebase Authentication with email and password authentication in my app.
```

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

### AI prompt for Firebase Google Sign-In assistance

Source: https://firebase.google.com/docs/auth/web/google-signin

Copy this prompt into an AI coding agent to get help setting up Firebase Authentication with Google Sign-In. It instructs the agent to install Firebase agent skills and assist with setup.

```text
Help me use Firebase in my app.
1. Make sure that **Firebase agent skills** are installed and updated. For Claude Code, Codex, or Cursor agents, help me install the Firebase plugin. For other agents, run `npx skills add firebase/agent-skills`.  Always try to use **Firebase agent skills** for Firebase-related tasks.
2. Help me set up and use Firebase Authentication with Google Sign-In in my app.
```

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

### Install and deploy extension from local source

Source: https://firebase.google.com/docs/extensions/publishers/upload-and-publish

Use these commands to test your extension in a real project by installing it from local source and deploying it. This is part of the recommended development cycle for rapid iteration.

```shell
firebase ext:install /path/to/extension
firebase deploy --only extensions
```

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

### Deploy the default Hosting site to a preview channel

Source: https://firebase.google.com/docs/hosting/multisites

Run this command from the root of your local project directory to deploy the Hosting content and configuration of the default Hosting site at a preview URL.

```bash
firebase hosting:channel:deploy \   CHANNEL_ID
```

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

### currentTimestamp example

Source: https://firebase.google.com/docs/reference/kotlin/com/google/firebase/firestore/pipeline/Expression

Example showing how to get the current server timestamp.

```kotlin
// Get the current server timestamp
currentTimestamp()
```

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

### Initialize Firebase Hosting GitHub Action (existing Hosting setup)

Source: https://firebase.google.com/docs/hosting/github-integration

Run this command from the root of your local directory if you have ALREADY set up Firebase Hosting. It sets up only the GitHub Action part of Hosting.

```shell
firebase init hosting:github
```

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

### No-op beforeCreate blocking function

Source: https://firebase.google.com/docs/functions/1st-gen/auth-blocking-events-1st

A no-op function to get started with blocking functions. Add it to index.js. The implementation of custom auth logic is omitted; see the following sections to learn how to implement your blocking functions and Common scenarios for specific examples.

```javascript
const functions = require('firebase-functions/v1');

exports.beforeCreate = functions.auth.user().beforeCreate((user, context) => {
  // TODO
});
```

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

### Worked example: Install a function kit with project flag

Source: https://firebase.google.com/docs/extensions/migration-best-practices

Example of installing the @firebase-function-kits/firestore-bigquery-export kit for a specific project. The command prompts for kit name, instance name, and parameters.

```shell
firebase functions:kits:install --package @firebase-function-kits/firestore-bigquery-export --project my-project
```

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

### collectionId usage example

Source: https://firebase.google.com/docs/reference/kotlin/com/google/firebase/firestore/pipeline/Expression

Example showing how to get the collection ID from the 'path' field.

```kotlin
// Get the collection ID from the 'path' field
field("path").collectionId()
```

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

### Initialize apphosting.yaml with Firebase CLI

Source: https://firebase.google.com/docs/app-hosting/configure

Run this command to create a basic starter apphosting.yaml file with example configuration.

```shell
firebase init apphosting
```

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

### Serve a specific Hosting site (not recommended)

Source: https://firebase.google.com/docs/hosting/multisites

This command is not recommended; use emulators:start instead. It serves the Hosting content and configuration of the specified Hosting site at a locally hosted URL.

```bash
firebase serve --only hosting:TARGET_NAME
```

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

### arrayFirst usage example

Source: https://firebase.google.com/docs/reference/kotlin/com/google/firebase/firestore/pipeline/Expression

Example showing how to get the first element of the 'myArray' field.

```kotlin
// Get the first element of the 'myArray' field.
arrayFirst(field("myArray"))
```

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

### vectorLength usage example

Source: https://firebase.google.com/docs/reference/kotlin/com/google/firebase/firestore/pipeline/Expression

Example showing how to get the vector length (dimension) of the field 'embedding'.

```kotlin
// Get the vector length (dimension) of the field 'embedding'.
vectorLength(field("embedding"))
```

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

### Output of ext:list command

Source: https://firebase.google.com/docs/extensions/migration-best-practices

Sample output showing the list of installed extensions, including instance IDs, states, versions, and replacement kits.

```text
» firebase ext:list
i  extensions: ensuring required API firebaseextensions.googleapis.com is enabled...
i  extensions: list of extensions installed in my-project:
┌────────────────────────────────────┬───────────┬────────────────────────────────┬────────┬─────────┬─────────────────────┬───────────────────────────────────────────────────┐
│ Extension                          │ Publisher │ Instance ID                    │ State  │ Version │ Your last update    │ Replacement Kit                                   │
├────────────────────────────────────┼───────────┼────────────────────────────────┼────────┼─────────┼─────────────────────┼───────────────────────────────────────────────────┤
│ firebase/firestore-bigquery-export │ firebase  │ firestore-bigquery-export-zbrp │ ACTIVE │ 0.3.3   │ 2026-09-06 22:31:04 │ @firebase-function-kits/firestore-bigquery-export │
├────────────────────────────────────┼───────────┼────────────────────────────────┼────────┼─────────┼─────────────────────┼───────────────────────────────────────────────────┤
│ firebase/firestore-bigquery-export │ firebase  │ firestore-bigquery-export      │ ACTIVE │ 0.3.2   │ 2026-06-03 17:41:24 │ @firebase-function-kits/firestore-bigquery-export │
└────────────────────────────────────┴───────────┴────────────────────────────────┴────────┴─────────┴─────────────────────┴───────────────────────────────────────────────────┘
⚠ Notice: Firebase Extensions will shut down on March 31, 2027. Learn more: https://firebase.google.com/docs/extensions/faq-and-troubleshooting
```

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

### field function example with FieldPath

Source: https://firebase.google.com/docs/reference/kotlin/com/google/firebase/firestore/pipeline/Expression

Example of using field with a FieldPath to get the 'address.city' field.

```kotlin
// Get the 'address.city' field
field(FieldPath.of("address", "city"))
```

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

### Configure workspace onStart with npm watch commands and openFiles

Source: https://firebase.google.com/docs/studio/devnix-reference

Use idx.workspace.onStart to run commands whenever the workspace is opened. The example starts frontend and backend watchers and opens src/index.ts.

```nix
{pkgs, ...}: {
  idx.workspace.onStart = {
    npm-watch-fe = "npm run watch:frontend";
    npm-watch-be = "npm run watch:backend";
    # files to open when the workspace is (re)opened.
    default.openFiles = [ "src/index.ts" ];
  };
}
```

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

### arrayFirst usage example

Source: https://firebase.google.com/docs/reference/kotlin/com/google/firebase/firestore/pipeline/Expression

Example of using arrayFirst to get the first element of the 'myArray' field.

```kotlin
// Get the first element of the 'myArray' field.
arrayFirst("myArray")
```

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

### Example: List Remote Config experiments

Source: https://firebase.google.com/docs/remote-config/automate-rc

Example command to list all Remote Config experiments for the project.

```bash
firebase remoteconfig:experiments:list
```

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

### startsWith(_:) with String Example

Source: https://firebase.google.com/docs/reference/swift/firebasefirestore/api/reference/Protocols/Expression

Example usage of `startsWith` with a literal string to check if a field starts with a prefix.

```swift
// Check if the "name" field starts with "Mr."
Field("name").startsWith("Mr.")
```

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

### Set up cities dataset for select stage examples

Source: https://firebase.google.com/docs/firestore/pipelines/stages/transformation/select

Creates sample documents in the `cities` collection used to demonstrate selecting only `name` and `location` fields for cities in Canada. Run this before the pipeline examples that follow.

```javascript
await db.collection("cities").doc("SF").set({
  name: "San Francisco",
  population: 800000,
  location: {country: "USA", state: "California"}
});

await db.collection("cities").doc("TO").set({
  name: "Toronto",
  population: 3000000,
  location: {country: "Canada", province: "Ontario"}
});
```
Tokens:
Raw