### Client Initialization

Source: https://github.com/chargebee/chargebee-php/wiki/Migration-guide-for-v4

Demonstrates the updated method for initializing the Chargebee client, including namespace changes and configuration parameters.

```php
use Chargebee\ChargeBee\Models\Environment;
Environment::configure("{site}", "{site_api_key}");
```

```php
use Chargebee\ChargebeeClient;
$chargebee = new ChargebeeClient([
    "site" => "{site}",
    "apiKey" => "{site_api_key}",
]);
```

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

### Install Chargebee PHP Client

Source: https://github.com/chargebee/chargebee-php/blob/master/README.md

Installs the Chargebee PHP client library using Composer and includes the autoloader for use in your project.

```php
composer require chargebee/chargebee-php

require_once('vendor/autoload.php');
```

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

### Accessing Response Properties

Source: https://github.com/chargebee/chargebee-php/wiki/Migration-guide-for-v4

Demonstrates the change in accessing properties within response objects, moving from method calls to direct property access.

```php
$result = Customer::retrieve("{customer-id}");
$customer = $result->customer();
$firstName = $customer->firstName();
```

```php
$result = $chargebee->customer()->retrieve("{customer-id}");
$customer = $result->customer;
$firstName = $customer->first_name;
```

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

### Input Parameter Naming Convention

Source: https://github.com/chargebee/chargebee-php/wiki/Migration-guide-for-v4

Shows the updated input parameter naming convention, which has shifted from `camelCase` to `snake_case` for method arguments.

```php
$result = Subscription::createWithItems("{customer-id}", array(
    "subscriptionItems" => array(
        array(
            "itemPriceId" => "day-pass-USD",
            "unitPrice" => 100
        ),
        array(
            "itemPriceId" => "basic-USD",
            "billingCycles" => 2,
            "quantity" => 1
        )
    )
));
```

```php
$result = $chargebee->subscription()->createWithItems("{customer-id}", [
    "subscription_items" => [
        [
            "item_price_id" => "day-pass-USD",
            "unit_price" => 100
        ],
        [
            "item_price_id" => "basic-USD",
            "billing_cycles" => 2,
            "quantity" => 1
        ]
    ]
]);
```

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

### Method Binding and Operations

Source: https://github.com/chargebee/chargebee-php/wiki/Migration-guide-for-v4

Illustrates the new approach to calling Chargebee API operations directly through the client instance, eliminating the need for importing individual model classes.

```php
use ChargeBee\ChargeBee\Environment;
use ChargeBee\ChargeBee\Models\Customer;
Environment::configure("{site}", "{site_api_key}");
$result = Customer::retrieve("{customer-id}");
```

```php
use Chargebee\ChargebeeClient;
$chargebee = new ChargebeeClient([
    "site" => "{site}",
    "apiKey" => "{site_api_key}",
]);
$response = $chargebee->customer()->retrieve("{customer-id}");
```

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

### Response Object Structure

Source: https://github.com/chargebee/chargebee-php/wiki/Migration-guide-for-v4

Compares the response object structure before and after the update, highlighting the change from a generic `Result` class to specific response classes for each action.

```php
$customerResponse     = Customer::retrieve("{customer-id}"); 
$subscriptionResponse = Subscription::retrieve("{customer-id}");

echo get_class($customerResponse) . "\n";
echo get_class($subscriptionResponse) . "\n";
```

```console
ChargeBee\ChargeBee\Result
ChargeBee\ChargeBee\Result
```

```php
$customerResponse     = $chargebee->customer()->retrieve("{customer-id}"); 
$subscriptionResponse = $chargebee->subscription()->retrieve("{subs-id}");

echo get_class($customerResponse) . "\n";
echo get_class($subscriptionResponse) . "\n";
```

```console
Chargebee\Responses\CustomerResponse\RetrieveCustomerResponse
Chargebee\Responses\SubscriptionResponse\RetrieveSubscriptionResponse
```

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

### List API Filters - ID Filter

Source: https://github.com/chargebee/chargebee-php/wiki/Migration-guide-for-v4

Demonstrates the updated syntax for passing filters in list APIs, specifically for the 'id' parameter with an 'is' condition.

```php
$result = Subscription::all([
    "id[is]" => "{subscription-id}"
]);
```

```php
$result = $chargebee->subscription()->all([
    "id" => ["is" => "{subscription-id}"]
]);
```

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

### List API Filters - Status Filter

Source: https://github.com/chargebee/chargebee-php/wiki/Migration-guide-for-v4

Illustrates the updated syntax for passing filters in list APIs, specifically for the 'status' parameter with an 'in' condition.

```php
$result = Subscription::all([
    "status[in]" => ["cancelled"],
    "limit" => 2,
]);
```

```php
$result = $chargebeeClient->subscription()->all([
    "status" => ["in" => ["cancelled"]],
    "limit" => 2,
]);
```

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

### Create a New Subscription

Source: https://github.com/chargebee/chargebee-php/blob/master/README.md

Demonstrates how to create a new subscription with specified items using the Chargebee PHP client. It initializes the client with site and API key, then calls the create method on the subscription object.

```php
use Chargebee\ChargebeeClient;

$chargebee = new ChargebeeClient(options: [
    "site" => "{your_site}",
    "apiKey" => "{your_apiKey}",
]);

$result = $chargebee->subscription()->createWithItems("customer_id", [
    "subscription_items" => [
        [
            "item_price_id" => "Montly-Item",
            "quantity" => "3",
        ]
    ]
]);
$subscription = $result->subscription;
$customer = $result->customer;
```

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

### Create an Idempotent Customer Request

Source: https://github.com/chargebee/chargebee-php/blob/master/README.md

Shows how to create a customer with an idempotency key to ensure safe retries of POST requests. It includes initializing the client, making the customer creation call, and retrieving response headers and idempotency status.

```php
use Chargebee\ChargebeeClient;

$chargebee = new ChargebeeClient(options: [
    "site" => "{your_site}",
    "apiKey" => "{your_apiKey}",
]);
$responseCustomer = $chargebee->customer()->create([
    "first_name" => "John",
    "last_name" => "Doe",
    "email" => "john@test.com",
    "card" => [
        "first_name" => "Joe",
        "last_name" => "Doe",
        "number" => "4012888888881881",
        "expiry_month" => "10",
        "expiry_year" => "29",
        "cvv" => "231"
        ]
    ],
    [
        "chargebee-idempotency-key" => "<<UUID>>" // Replace <<UUID>> with a unique string
    ]
);
$responseHeaders = $responseCustomer->getResponseHeaders(); // Retrieves response headers
print_r($responseHeaders);
$idempotencyReplayedValue = $responseCustomer->isIdempotencyReplayed(); // Retrieves Idempotency replayed header value
print_r($idempotencyReplayedValue);
```

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

### Configure Rate Limit Retry Logic

Source: https://github.com/chargebee/chargebee-php/blob/master/README.md

Demonstrates how to initialize the Chargebee client with custom retry configurations for rate-limited requests. This includes enabling the retry mechanism, setting the maximum number of retries, the delay between retries, and specifying which HTTP status codes should trigger a retry.

```php
use Chargebee\ChargebeeClient;

// Retry Configurations
$retryConfig = new RetryConfig();
$retryConfig->setEnabled(true); // Enable retry mechanism
$retryConfig->setMaxRetries(5); // Maximum number of reties
$retryConfig->setDelayMs(1000); // Delay in milliseconds before retrying
$retryConfig->setRetryOn([429]); // Retry on 429 HTTP status codes

$chargebee = new ChargebeeClient(options: [
    "site" => "{your_site}",
    "apiKey" => "{your_apiKey}",
    "retryConfig" => $retryConfig,
]);

// ... your Chargebee API operations below ...
```

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

### Configure Chargebee SDK Retry Logic

Source: https://github.com/chargebee/chargebee-php/blob/master/README.md

Demonstrates how to enable and customize the built-in retry logic for the Chargebee PHP client. This includes setting the maximum number of retries, delay between retries, and specific HTTP status codes to retry on.

```php
use Chargebee\ChargebeeClient;
use Chargebee\Models\RetryConfig;

// Retry Configurations
$retryConfig = new RetryConfig();
$retryConfig->setEnabled(true); // Enable retry mechanism
$retryConfig->setMaxRetries(5); // Maximum number of retries
$retryConfig->setDelayMs(1000); // Delay in milliseconds before retrying
$retryConfig->setRetryOn([500, 502, 503, 504]); // Retry on these HTTP status codes

$chargebee = new ChargebeeClient(options: [
    "site" => "{your_site}",
    "apiKey" => "{your_apiKey}",
    "retryConfig" => $retryConfig,
]);

// ... your Chargebee API operations below ...
```

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