### Perform simple GET request with deserialization

Source: https://restsharp.dev/docs/usage/execute

Use GetAsync<TResponse> to make a GET call and deserialize the response directly from a resource string.

```csharp
var response = await client.GetAsync<TResponse>("endpoint?foo=bar", cancellationToken);
```

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

### Create RestClient with RestClientOptions

Source: https://restsharp.dev/docs/usage/client

Creates a client using the options object of type RestClientOptions. This example sets a timeout of one second.

```csharp
// Creates a client using the options object  

var options = new RestClientOptions("https://localhost:5000") {  

    Timeout = TimeSpan.FromSeconds(1)  

};  

var client = new RestClient(options);  

```

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

### Create a RestRequest with default GET method

Source: https://restsharp.dev/docs/usage/request

Creates a new RestRequest with the resource sub-path. The default request type is GET.

```csharp
var request = new RestRequest(resource); // resource is the sub-path of the client base path  
```

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

### Basic RestSharp GET request with authentication

Source: https://restsharp.dev/docs/intro

Creates a RestClient with basic authentication and performs an asynchronous GET request. The response is a RestResponse containing headers, content, and HTTP status. The cancellation token comes from the caller.

```csharp
using RestSharp;  

using RestSharp.Authenticators;  

  

var options = new RestClientOptions("https://api.twitter.com/1.1") {  

    Authenticator = new HttpBasicAuthenticator("username", "password")  

};  

var client = new RestClient(options);  

var request = new RestRequest("statuses/home_timeline.json");  

// The cancellation token comes from the caller. You can still make a call without it.  

var response = await client.GetAsync(request, cancellationToken);  
```

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

### Add a header to a request

Source: https://restsharp.dev/docs/usage/request

Example of adding a header parameter to a request using the AddHeader method.

```csharp
var request = new RestRequest("/path").AddHeader("X-Key", someKey);  
```

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

### Perform advanced GET request with object parameters

Source: https://restsharp.dev/docs/usage/execute

Use an object to compose the resource string where properties matching URL segments are replaced and others are added as query parameters.

```csharp
var client = new RestClient("https://example.org");  

var args = new {  

    id = "123",  

    foo = "bar"  

};  

// Will make a call to https://example.org/endpoint/123?foo=bar  

var response = await client.GetAsync<TResponse>("endpoint/{id}", args, cancellationToken);
```

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

### Add query string parameter

Source: https://restsharp.dev/docs/usage/request

Appends a parameter to the URL as a query string, resulting in a GET request to the specified URL.

```csharp
var client = new RestClient("https://search.me");  

var request = new RestRequest("search")  

    .AddParameter("foo", "bar");  

var response = await client.GetAsync<SearchResponse>(request);
```

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

### Configure TwitterClient with ASP.NET Core Options

Source: https://restsharp.dev/docs/usage/example

Alternative constructor implementation using IOptions for dependency injection.

```csharp

public record TwitterClientOptions(string ApiKey, string ApiSecret);  

  

public TwitterClient(IOptions<TwitterClientOptions> options) {  

    var tokenRequest = new OAuth2TokenRequest(  

        "https://api.twitter.com/oauth2/token",  

        options.Value.ApiKey,  

        options.Value.ApiSecret  

    );  

    var opt = new RestClientOptions("https://api.twitter.com/2") {  

        Authenticator = new OAuth2ClientCredentialsAuthenticator(tokenRequest)  

    };  

    _client = new RestClient(opt);  

}  


```

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

### Add files using extension methods

Source: https://restsharp.dev/docs/usage/request

Use extension methods to add files from disk, byte arrays, or streams without manually creating a FileParameter.

```csharp
// Adds a file from disk  

AddFile(parameterName, filePath, contentType);  

  

// Adds an array of bytes  

AddFile(parameterName, bytes, fileName, contentType);  

  

// Adds a stream returned by the getFile function  

AddFile(parameterName, getFile, fileName, contentType);
```

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

### RestClient with base URL and configuration

Source: https://restsharp.dev/docs/advanced/configuration

Provides base URL as first argument and configuration function as second.

```csharp
var client = new RestClient("https://localhost:5000/api", options => {  
    options.DisableCharset = true  
});  
```

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

### Create RestClient with base URL only

Source: https://restsharp.dev/docs/usage/client

Creates a client with default options to call a given base URL. The base URL can be left empty, in which case absolute paths must be used for each call.

```csharp
// Creates a client with default options to call a given base URL  

var client = new RestClient("https://localhost:5000");  

```

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

### RestSharp GET request with generic deserialization

Source: https://restsharp.dev/docs/intro

Uses the generic GetAsync<T> overload to automatically deserialize the response into a .NET class. The cancellation token comes from the caller.

```csharp
using RestSharp;  

using RestSharp.Authenticators;  

  

var options = new RestClientOptions("https://api.twitter.com/1.1") {  

    Authenticator = new HttpBasicAuthenticator("username", "password")  

};  

var client = new RestClient(options);  

  

var request = new RestRequest("statuses/home_timeline.json");  

  

// The cancellation token comes from the caller. You can still make a call without it.  

var timeline = await client.GetAsync<HomeTimeline>(request, cancellationToken);  
```

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

### Create RestClient with RestClientOptions

Source: https://restsharp.dev/docs/advanced/configuration

Creates a RestClient with custom options, setting DisableCharset to true.

```csharp
var options = new RestClientOptions("https://localhost:5000/api") {  
    DisableCharset = true  
};  
var client = new RestClient(options);  
```

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

### Configure RedirectOptions in RestClientOptions

Source: https://restsharp.dev/docs/advanced/configuration

Demonstrates how to instantiate RedirectOptions within RestClientOptions to customize redirect behavior, such as setting the maximum number of redirects and controlling authorization forwarding.

```csharp
var options = new RestClientOptions("https://api.example.com") {  

    RedirectOptions = new RedirectOptions {  

        FollowRedirects = true,  

        MaxRedirects = 10,  

        ForwardAuthorization = true,  

        FollowRedirectsToInsecure = false  

    }  

};  
```

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

### RestSharp JSON GET with GetJsonAsync

Source: https://restsharp.dev/docs/intro

Calls an API that accepts and returns JSON payloads using the GetJsonAsync extension method, which automatically serializes the request body to JSON and deserializes the response to the specified type.

```csharp
var client = new RestClient(options);  

var timeline = await client.GetJsonAsync<HomeTimeline>("statuses/home_timeline.json", cancellationToken);  
```

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

### Create RestClient with simple client factory

Source: https://restsharp.dev/docs/usage/client

Enables the client factory by setting useClientFactory to true. The factory caches HttpClient instances per distinct base URL, ignoring certain options after the first instance is created.

```csharp
var options = new RestClientOptions("https://api.twitter.com/2");  

var client = new RestClient(options, useClientFactory: true);  

```

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

### RestClient constructor with configuration function

Source: https://restsharp.dev/docs/advanced/configuration

Constructor that accepts a configuration function to override default options.

```csharp
public RestClient(  
    ConfigureRestClient?    configureRestClient     = null,  
    ConfigureHeaders?       configureDefaultHeaders = null,  
    ConfigureSerialization? configureSerialization  = null,  
    bool                    useClientFactory        = false  
)  
```

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

### HeaderInterceptor class overriding BeforeHttpRequest

Source: https://restsharp.dev/docs/advanced/interceptors

Defines an interceptor that adds a header to the HTTP request message. Overrides BeforeHttpRequest and returns ValueTask.CompletedTask. This is a simple example; RestSharp already provides built-in methods for adding headers.

```csharp
// This interceptor adds a header to the request  

// You'd not normally use this interceptor, as RestSharp already has a method   

// to add headers to the request  

class HeaderInterceptor(string headerName, string headerValue) : Interceptors.Interceptor {  

    public override ValueTask BeforeHttpRequest(HttpRequestMessage requestMessage, CancellationToken cancellationToken) {  

        requestMessage.Headers.Add(headerName, headerValue);  

        return ValueTask.CompletedTask;  

    }  

}  
```

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

### Implement TwitterClient class

Source: https://restsharp.dev/docs/usage/example

Provides the implementation of ITwitterClient, including RestClient configuration with OAuth2 authentication and resource disposal.

```csharp

public class TwitterClient : ITwitterClient, IDisposable {  

    readonly RestClient _client;  

  

    public TwitterClient(string apiKey, string apiKeySecret) {  

        var tokenRequest = new OAuth2TokenRequest(  

            "https://api.twitter.com/oauth2/token",  

            apiKey,  

            apiKeySecret  

        );  

        var options = new RestClientOptions("https://api.twitter.com/2") {  

            Authenticator = new OAuth2ClientCredentialsAuthenticator(tokenRequest)  

        };  

        _client = new RestClient(options);  

    }  

  

    public async Task<TwitterUser> GetUser(string user) {  

        var response = await _client.GetAsync<TwitterSingleObject<TwitterUser>>(  

            "users/by/username/{user}",  

            new { user }  

        );  

        return response!.Data;  

    }  

  

    record TwitterSingleObject<T>(T Data);  

  

    public void Dispose() {  

        _client?.Dispose();  

        GC.SuppressFinalize(this);  

    }  

}  


```

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

### Implement Custom Serializer with IRestSerializer

Source: https://restsharp.dev/docs/advanced/serialization

Create a custom serializer by implementing the IRestSerializer interface, shown here using System.Text.Json.

```csharp
public class SimpleJsonSerializer : IRestSerializer {  

    public string? Serialize(object? obj) => obj == null ? null : JsonSerializer.Serialize(obj);  

  

    public string? Serialize(Parameter bodyParameter) => Serialize(bodyParameter.Value);  

  

    public T? Deserialize<T>(RestResponse response) => JsonSerializer.Deserialize<T>(response.Content!);  

  

    public ContentType ContentType { get; set; } = ContentType.Json;  

  

    public ISerializer   Serializer           => this;  

    public IDeserializer Deserializer         => this;  

    public DataFormat    DataFormat           => DataFormat.Json;  

    public string[]      AcceptedContentTypes => ContentType.JsonAccept;  

    public SupportsContentType SupportsContentType   

        => contentType => contentType.Value.EndsWith("json", StringComparison.InvariantCultureIgnoreCase);  

}  
```

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

### Configure RestClient with lambda

Source: https://restsharp.dev/docs/advanced/configuration

Configures RestClient using a lambda that sets BaseUrl and DisableCharset.

```csharp
var client = new RestClient(options => {  
    options.BaseUrl = new Uri("https://localhost:5000/api");  
    options.DisableCharset = true;  
});  
```

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

### Create a RestRequest with POST method

Source: https://restsharp.dev/docs/usage/request

Creates a new RestRequest with the resource and explicitly sets the HTTP method to POST using the constructor overload.

```csharp
var request = new RestRequest(resource, Method.Post);  
```

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

### Configure System.Text.Json options

Source: https://restsharp.dev/docs/advanced/serialization

Use the UseSystemTextJson extension method to provide custom JsonSerializerOptions to the RestClient.

```csharp
var client = new RestClient(  

    options,   

    configureSerialization: s => s.UseSystemTextJson(new JsonSerializerOptions {...})  

);  
```

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

### Configure FileParameterOptions

Source: https://restsharp.dev/docs/usage/request

Use FileParameterOptions to customize file upload headers, which is useful for handling non-ASCII filenames.

```csharp
var options = new FileParameterOptions {  

    DisableFilenameEncoding = true,  

    DisableFilenameStar = false  

};  

request.AddFile("file", filePath, options: options);
```

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

### Configure CSV Serialization with CsvConfiguration

Source: https://restsharp.dev/docs/advanced/serialization

Supply a custom CsvConfiguration instance to the UseCsvHelper extension method.

```csharp
var client = new RestClient(  

    options,   

    configureSerialization: s => s.UseCsvHelper(  

        new CsvConfiguration(CultureInfo.InvariantCulture) {...}  

    )  

);  
```

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

### Configure XML serializer

Source: https://restsharp.dev/docs/advanced/serialization

Use the UseXmlSerializer extension method to enable the XML serializer, which requires the RestSharp.Serializers.Xml package.

```csharp
var client = new RestClient(  

    options,   

    configureSerialization: s => s.UseXmlSerializer()  

);  
```

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

### Configure CSV Serialization

Source: https://restsharp.dev/docs/advanced/serialization

Use the UseCsvHelper extension method to configure the RestClient for CSV serialization.

```csharp
var client = new RestClient(  

    options,   

    configureSerialization: s => s.UseCsvHelper()  

);  
```

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

### Add a cookie with explicit path and domain

Source: https://restsharp.dev/docs/usage/request

Use the four-parameter AddCookie overload to explicitly define the path and domain for the cookie.

```csharp
request.AddCookie("foo", "bar", "/path", "example.com");  
```

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

### Configure OAuth2ClientCredentialsAuthenticator

Source: https://restsharp.dev/docs/usage/example

Sets up an OAuth2TokenRequest and assigns it to the RestClientOptions Authenticator. The authenticator manages token lifecycle automatically using an internal HttpClient.

```csharp
var tokenRequest = new OAuth2TokenRequest(  

    "https://api.twitter.com/oauth2/token",  

    apiKey,  

    apiKeySecret  

);  

  

var options = new RestClientOptions("https://api.twitter.com/2") {  

    Authenticator = new OAuth2ClientCredentialsAuthenticator(tokenRequest)  

};  
```

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

### OAuth1 0-legged

Source: https://restsharp.dev/docs/advanced/authenticators

Perform 0-legged OAuth by providing null for the consumerSecret in the ForAccessToken method.

```csharp
var authenticator = OAuth1Authenticator.ForAccessToken(  

    consumerKey, null, oauthToken, oauthTokenSecret  

);  
```

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

### Default NewtonsoftJson settings

Source: https://restsharp.dev/docs/advanced/serialization

The default configuration for Newtonsoft.Json includes specific settings for contract resolution, null handling, and formatting.

```csharp
JsonSerializerSettings DefaultSettings = new JsonSerializerSettings {  

    ContractResolver     = new CamelCasePropertyNamesContractResolver(),  

    DefaultValueHandling = DefaultValueHandling.Include,  

    TypeNameHandling     = TypeNameHandling.None,  

    NullValueHandling    = NullValueHandling.Ignore,  

    Formatting           = Formatting.None,  

    ConstructorHandling  = ConstructorHandling.AllowNonPublicDefaultConstructor  

};  
```

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

### Add RestSharp NuGet package

Source: https://restsharp.dev/docs/intro

Command to add the RestSharp NuGet package to a .NET project using the dotnet CLI.

```bash
dotnet add package RestSharp  
```

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

### Configure a custom serializer

Source: https://restsharp.dev/docs/advanced/serialization

Use the configureSerialization parameter in the RestClient constructor to register a custom serializer implementation.

```csharp
var client = new RestClient(  

    options,   

    configureSerialization: s => s.UseSerializer(() => new CustomSerializer())  

);
```

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

### RestClient constructor signature

Source: https://restsharp.dev/docs/advanced/configuration

Primary constructor for RestClient. Accepts RestClientOptions and optional delegates for default headers, serialization, and client factory usage.

```csharp
public RestClient(  
    RestClientOptions       options,  
    ConfigureHeaders?       configureDefaultHeaders = null,  
    ConfigureSerialization? configureSerialization  = null,  
    bool                    useClientFactory        = false  
)  
```

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

### Add a file using FileParameter

Source: https://restsharp.dev/docs/usage/request

Use the AddFile method with a FileParameter object to attach a file to a request.

```csharp
request.AddFile(fileParameter);
```

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

### Migrating hook to CompatibilityInterceptor

Source: https://restsharp.dev/docs/advanced/interceptors

Shows how to migrate the deprecated OnBeforeDeserialization hook to an interceptor using CompatibilityInterceptor. The interceptor is added to the request's Interceptors collection.

```csharp
var request = new RestRequest("success") {  

    Interceptors = [new CompatibilityInterceptor {  

        OnBeforeDeserialization = _ => throw new Exception(exceptionMessage)  

    }]  

};  
```

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

### Configure NewtonsoftJson serializer

Source: https://restsharp.dev/docs/advanced/serialization

Use the UseNewtonsoftJson extension method to enable the Newtonsoft.Json serializer via the RestSharp.Serializers.NewtonsoftJson package.

```csharp
var client = new RestClient(  

    options,   

    configureSerialization: s => s.UseNewtonsoftJson()  

);  
```

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

### Implement Custom IAuthenticator

Source: https://restsharp.dev/docs/advanced/authenticators

Demonstrates registering a custom class that implements IAuthenticator with RestClientOptions. The Authenticate method is invoked before request execution, allowing full access to request data.

```csharp
var authenticator = new SuperAuthenticator(); // implements IAuthenticator  

var options = new RestClientOptions("https://example.com") {  

    Authenticator = authenticator  

};  

var client = new RestClient(options);
```

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

### Adding an interceptor to the client via RestClientOptions

Source: https://restsharp.dev/docs/advanced/interceptors

Creates a RestClient with an interceptor added to the client options. The interceptor will be executed for every request made by that client.

```csharp
var options = new RestClientOptions("https://api.example.com") {  

    Interceptors = [new HeaderInterceptor("Authorization", token)]  

};  

var client = new RestClient(options);  
```

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

### Add parameters using AddObject

Source: https://restsharp.dev/docs/usage/request

Collects parameters in an object and adds them to the request in one call. This works with primitive types and collections of primitive types.

```csharp
var params = new {  

    status = 1,  

    priority = "high",  

    ids = new [] { "123", "456" }  

};  

request.AddObject(params);
```

```csharp
request.AddParameter("status", 1);  

request.AddParameter("priority", "high");  

request.AddParameter("ids", "123,456");
```

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

### AddParameter with explicit CultureInfo

Source: https://restsharp.dev/docs/advanced/configuration

Demonstrates how to pass a specific CultureInfo to AddParameter to override the default invariant culture formatting.

```csharp
request.AddParameter("price", 1234.56, culture: new CultureInfo("da-DK"));  

// Sends: price=1234,56  
```

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

### Add default query string parameter to client

Source: https://restsharp.dev/docs/usage/request

Adds a parameter to every request made by the client instance.

```csharp
client.AddDefaultQueryParameter("foo", "bar");
```

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

### OAuth1 xAuth

Source: https://restsharp.dev/docs/advanced/authenticators

Create an xAuth authenticator using OAuth1Authenticator.ForClientAuthentication to exchange credentials directly for an access token.

```csharp
var authenticator = OAuth1Authenticator.ForClientAuthentication(  

    consumerKey, consumerSecret, username, password  

);  
```

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

### Add header parameter methods

Source: https://restsharp.dev/docs/usage/request

Lists the available methods to add header parameters to a request. AddHeader converts the value to string when using the generic overload, and AddOrUpdateHeader replaces an existing header.

```csharp
AddHeader(string name, string value);  

AddHeader<T>(string name, T value);           // value will be converted to string  

AddOrUpdateHeader(string name, string value); // replaces the header if it already exists  
```

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

### ExecuteGetAsync and other method-specific overloads

Source: https://restsharp.dev/docs/usage/execute

Overloads that set the HTTP method for you. They return RestResponse and do not throw on server errors, allowing graceful handling of remote errors.

```csharp
Task<RestResponse> ExecuteGetAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> ExecutePostAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> ExecutePutAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> ExecuteDeleteAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> ExecuteHeadAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> ExecuteOptionsAsync(RestRequest request, CancellationToken cancellationToken)  
```

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

### Configure JwtAuthenticator

Source: https://restsharp.dev/docs/advanced/authenticators

Initializes a JwtAuthenticator with a token and assigns it to RestClientOptions. This automatically adds an Authorization header with the Bearer scheme to requests.

```csharp
var authenticator = new JwtAuthenticator(myToken);  

var options = new RestClientOptions("https://example.com") {  

    Authenticator = authenticator  

};  

var client = new RestClient(options);
```

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

### ConfigureMessageHandler with MockHttp

Source: https://restsharp.dev/docs/advanced/configuration

Sets ConfigureMessageHandler to replace the default handler with a MockHttp handler for testing. The handler created by RestSharp is ignored.

```csharp
var mockHttp = new MockHttpMessageHandler();  
// Configure the MockHttp handler to do the checks  
...  

var options = new RestClientOptions(Url) {  
    ConfigureMessageHandler = _ => mockHttp  
};  
using var client = new RestClient(options);  
```

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

### Using OnBeforeRequest hook before migration

Source: https://restsharp.dev/docs/advanced/interceptors

Shows the old way of using the OnBeforeDeserialization hook on a RestRequest. This hook is deprecated and should be migrated to interceptors.

```csharp
var request = new RestRequest("success");  

request.OnBeforeDeserialization += _ => throw new Exception(exceptionMessage);  
```

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

### Add default parameter to client

Source: https://restsharp.dev/docs/usage/request

Use AddDefaultParameter to include a parameter in every request made by the client.

```csharp
client.AddDefaultParameter("foo", "bar");
```

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

### OAuth1 access token with verifier

Source: https://restsharp.dev/docs/advanced/authenticators

Use the overload of ForAccessToken that accepts a verifier value if the second step of the OAuth1 flow provided one.

```csharp
var authenticator = OAuth1Authenticator.ForAccessToken(  

    consumerKey, consumerSecret, oauthToken, oauthTokenSecret, verifier  

);  
```

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

### OAuth1 access token

Source: https://restsharp.dev/docs/advanced/authenticators

Use OAuth1Authenticator.ForAccessToken to retrieve an access token in the third step of a 3-legged OAuth1 flow.

```csharp
var authenticator = OAuth1Authenticator.ForAccessToken(  

    consumerKey, consumerSecret, oauthToken, oauthTokenSecret  

);  

var options = new RestClientOptions("https://api.twitter.com") {  

    Authenticator = authenticator  

};  

var client = new RestClient(options);  

var request = new RestRequest("oauth/access_token");  
```

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

### IRestClient GetAsync and other non-deserializing extensions

Source: https://restsharp.dev/docs/usage/execute

IRestClient extensions for making requests without deserialization. They throw an exception if the server returns an error, even if the client is configured to not throw exceptions.

```csharp
Task<RestResponse> GetAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> PostAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> PutAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> PatchAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> DeleteAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> HeadAsync(RestRequest request, CancellationToken cancellationToken)  
Task<RestResponse> OptionsAsync(RestRequest request, CancellationToken cancellationToken)  
```

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

### GetAsync<T> and other deserializing extensions

Source: https://restsharp.dev/docs/usage/execute

Extensions that return only the deserialized object. They throw an exception if the server returns an error, as there is no other way to surface the error to the caller.

```csharp
Task<T> GetAsync<T>(RestRequest request, CancellationToken cancellationToken)  
Task<T> PostAsync<T>(RestRequest request, CancellationToken cancellationToken)  
Task<T> PutAsync<T>(RestRequest request, CancellationToken cancellationToken)  
Task<T> PatchAsync<T>(RestRequest request, CancellationToken cancellationToken)  
Task<T> DeleteAsync<T>(RestRequest request, CancellationToken cancellationToken)  
Task<T> HeadAsync<T>(RestRequest request, CancellationToken cancellationToken)  
Task<T> OptionsAsync<T>(RestRequest request, CancellationToken cancellationToken)  
```

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

### Register RestClient as a singleton in Blazor

Source: https://restsharp.dev/docs/usage/client

Register the RestClient instance globally in your Blazor application using the HttpClient constructor to avoid platform-specific limitations.

```csharp
builder.Services.AddSingleton(new RestClient(new HttpClient()));
```

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

### RestClient constructors for custom HttpClient

Source: https://restsharp.dev/docs/advanced/configuration

These constructors accept an existing HttpClient and optional RestClientOptions or configuration functions. The disposeHttpClient parameter defaults to false, meaning the HttpClient is not disposed by RestClient.

```csharp
// Create a client using an existing HttpClient and RestClientOptions (optional)  

public RestClient(  

    HttpClient              httpClient,  

    RestClientOptions?      options,  

    bool                    disposeHttpClient      = false,  

    ConfigureSerialization? configureSerialization = null  

)  

  

// Create a client using an existing HttpClient and optional RestClient configuration function  

public RestClient(  

    HttpClient              httpClient,  

    bool                    disposeHttpClient      = false,  

    ConfigureRestClient?    configureRestClient    = null,  

    ConfigureSerialization? configureSerialization = null  

)  
```

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

### Multipart form-data parameter structure

Source: https://restsharp.dev/docs/usage/request

When files are attached, parameters are sent as part of a multipart/form-data request.

```http
Content-Type: text/plain; charset=utf-8  

Content-Disposition: form-data; name="parameterName"  

  

ParameterValue
```

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

### OAuth2TokenAuthenticator with custom token provider

Source: https://restsharp.dev/docs/advanced/authenticators

Uses OAuth2TokenAuthenticator with an async delegate to handle non-standard token flows.

```csharp
var options = new RestClientOptions("https://api.example.com") {  

    Authenticator = new OAuth2TokenAuthenticator(async cancellationToken => {  

        var token = await myCustomTokenService.GetTokenAsync(cancellationToken);  

        return new OAuth2Token(token.Value, token.ExpiresAt);  

    })  

};  

using var client = new RestClient(options);
```

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

### Add a pre-serialized string body with AddStringBody

Source: https://restsharp.dev/docs/usage/request

Use AddStringBody for pre-serialized payloads, ensuring you specify the content type for the remote endpoint.

```csharp
const json = "{ data: { foo: \"bar\" } }";  

request.AddStringBody(json, ContentType.Json);  
```

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

### Add a cookie with inferred domain

Source: https://restsharp.dev/docs/usage/request

Use the two-parameter AddCookie method to add a cookie where the domain is inferred from the request URL at execution time.

```csharp
request.AddCookie("foo", "bar");  
```

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

### RestClient constructor for custom HttpMessageHandler

Source: https://restsharp.dev/docs/advanced/configuration

This constructor creates a new HttpClient using the provided message handler. The disposeHandler parameter defaults to true, so the handler is disposed with the client; set it to false to keep the handler.

```csharp
public RestClient(  

    HttpMessageHandler      handler,  

    bool                    disposeHandler         = true,  

    ConfigureRestClient?    configureRestClient    = null,  

    ConfigureSerialization? configureSerialization = null  

)  
```

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

### Perform POST request with JSON response

Source: https://restsharp.dev/docs/usage/execute

Use PostJsonAsync to post an object as JSON and deserialize the response into a specific type.

```csharp
var request = new CreateOrder("123", "foo", 10100);  

// Will post the request object as JSON to "orders" and returns a   

// JSON response deserialized to OrderCreated    

var result = client.PostJsonAsync<CreateOrder, OrderCreated>("orders", request, cancellationToken);
```