Courier C# API Library

Note

The Courier C# API Library is currently in beta and we're excited for you to experiment with it!

This library has not yet been exhaustively tested in production environments and may be missing some features you'd expect in a stable release. As we continue development, there may be breaking changes that require updates to your code.

We'd love your feedback! Please share any suggestions, bug reports, feature requests, or general thoughts by filing an issue.

The Courier C# SDK provides convenient access to the Courier REST API from applications written in C#.

It is generated with Stainless.

The REST API documentation can be found on www.courier.com.

Installation

git clone [email protected]:trycourier/courier-csharp.git
dotnet add reference courier-csharp/src/Courier

Requirements

This library requires .NET Standard 2.0 or later.

Usage

See the examples directory for complete and runnable examples.

using System;
using System.Collections.Generic;
using System.Text.Json;
using Courier;
using Courier.Models;
using Courier.Models.Send;

CourierClient client = new();

SendMessageParams parameters = new()
{
    Message = new()
    {
        To = new UserRecipient() { UserID = "your_user_id" },
        Template = "your_template_id",
        Data = new Dictionary<string, JsonElement>()
        {
            { "foo", JsonSerializer.SerializeToElement("bar") }
        },
    },
};

var response = await client.Send.Message(parameters);

Console.WriteLine(response);

Client configuration

Configure the client using environment variables:

using Courier;

// Configured using the COURIER_API_KEY and COURIER_BASE_URL environment variables
CourierClient client = new();

Or manually:

using Courier;

CourierClient client = new() { ApiKey = "My API Key" };

Or using a combination of the two approaches.

See this table for the available options:

Property	Environment variable	Required	Default value
ApiKey	COURIER_API_KEY	true	-
BaseUrl	COURIER_BASE_URL	true	"https://api.courier.com"

Modifying configuration

To temporarily use a modified client configuration, while reusing the same connection and thread pools, call WithOptions on any client or service:

using System;

var response = await client
    .WithOptions(options =>
        options with
        {
            BaseUrl = "https://example.com",
            Timeout = TimeSpan.FromSeconds(42),
        }
    )
    .Send.Message(parameters);

Console.WriteLine(response);

Using a with expression makes it easy to construct the modified options.

The WithOptions method does not affect the original client or service.

Requests and responses

To send a request to the Courier API, build an instance of some Params class and pass it to the corresponding client method. When the response is received, it will be deserialized into an instance of a C# class.

For example, client.Send.Message should be called with an instance of SendMessageParams, and it will return an instance of Task<SendMessageResponse>.

Raw responses

The SDK defines methods that deserialize responses into instances of C# classes. However, these methods don't provide access to the response headers, status code, or the raw response body.

To access this data, prefix any HTTP method call on a client or service with WithRawResponse:

var response = await client.WithRawResponse.Send.Message(parameters);
var statusCode = response.Message.StatusCode;
var headers = response.Message.Headers;

For non-streaming responses, you can deserialize the response into an instance of a C# class if needed:

using System;
using Courier.Models.Send;

var response = await client.WithRawResponse.Send.Message(parameters);
SendMessageResponse deserialized = await response.Deserialize();
Console.WriteLine(deserialized);

Error handling

The SDK throws custom unchecked exception types:

• CourierApiException: Base class for API errors. See this table for which exception subclass is thrown for each HTTP status code:

Status	Exception
400	CourierBadRequestException
401	CourierUnauthorizedException
403	CourierForbiddenException
404	CourierNotFoundException
422	CourierUnprocessableEntityException
429	CourierRateLimitException
5xx	Courier5xxException
others	CourierUnexpectedStatusCodeException

Additionally, all 4xx errors inherit from Courier4xxException.

false

• CourierIOException: I/O networking errors.

• CourierInvalidDataException: Failure to interpret successfully parsed data. For example, when accessing a property that's supposed to be required, but the API unexpectedly omitted it from the response.

• CourierException: Base class for all exceptions.

Network options

Retries

The SDK automatically retries 2 times by default, with a short exponential backoff between requests.

Only the following error types are retried:

• Connection errors (for example, due to a network connectivity problem)
• 408 Request Timeout
• 409 Conflict
• 429 Rate Limit
• 5xx Internal

The API may also explicitly instruct the SDK to retry or not retry a request.

To set a custom number of retries, configure the client using the MaxRetries method:

using Courier;

CourierClient client = new() { MaxRetries = 3 };

Or configure a single method call using WithOptions:

using System;

var response = await client
    .WithOptions(options =>
        options with { MaxRetries = 3 }
    )
    .Send.Message(parameters);

Console.WriteLine(response);

Timeouts

Requests time out after 1 minute by default.

To set a custom timeout, configure the client using the Timeout option:

using System;
using Courier;

CourierClient client = new() { Timeout = TimeSpan.FromSeconds(42) };

Or configure a single method call using WithOptions:

using System;

var response = await client
    .WithOptions(options =>
        options with { Timeout = TimeSpan.FromSeconds(42) }
    )
    .Send.Message(parameters);

Console.WriteLine(response);

Undocumented API functionality

The SDK is typed for convenient usage of the documented API. However, it also supports working with undocumented or not yet supported parts of the API.

Response validation

In rare cases, the API may return a response that doesn't match the expected type. For example, the SDK may expect a property to contain a string, but the API could return something else.

By default, the SDK will not throw an exception in this case. It will throw CourierInvalidDataException only if you directly access the property.

If you would prefer to check that the response is completely well-typed upfront, then either call Validate:

var response = client.Send.Message(parameters);
response.Validate();

Or configure the client using the ResponseValidation option:

using Courier;

CourierClient client = new() { ResponseValidation = true };

Or configure a single method call using WithOptions:

using System;

var response = await client
    .WithOptions(options =>
        options with { ResponseValidation = true }
    )
    .Send.Message(parameters);

Console.WriteLine(response);

Semantic versioning

This package generally follows SemVer conventions, though certain backwards-incompatible changes may be released as minor versions:

1. Changes to library internals which are technically public but not intended or documented for external use. (Please open a GitHub issue to let us know if you are relying on such internals.)
2. Changes that we do not expect to impact the vast majority of users in practice.

We take backwards-compatibility seriously and work hard to ensure you can rely on a smooth upgrade experience.

We are keen for your feedback; please open an issue with questions, bugs, or suggestions.