CODEWITHSUNDEEP
c#.net-coredotnet-httpclient.net-core-2.1httpclientfactory
Jim Fritchman
Jim Fritchman

Reputation: 643

How to use HttpClientHandler with HttpClientFactory in .NET Core

I want to use the HttpClientFactory that is available in .NET Core 2.1 but I also want to use the HttpClientHandler to utilize the AutomaticDecompression property when creating HttpClients.

I am struggling because the .AddHttpMessageHandler<> takes a DelegatingHandler not a HttpClientHandler.

Does anyone know how to get this to work?

Thanks, Jim

Upvotes: 60

Views: 75126

Answers (2)

trueboroda
trueboroda

Reputation: 2890

More properly to define primary HttpMessageHandler via ConfigurePrimaryHttpMessageHandler() method of HttpClientBuilder. See example below to configure typed client how.

services.AddHttpClient<TypedClient>()
    .ConfigureHttpClient((sp, httpClient) =>
    {
        var options = sp.GetRequiredService<IOptions<SomeOptions>>().Value;
        httpClient.BaseAddress = options.Url;
        httpClient.Timeout = options.RequestTimeout;
    })
    .SetHandlerLifetime(TimeSpan.FromMinutes(5))
    .ConfigurePrimaryHttpMessageHandler(x => new HttpClientHandler() 
    {
        AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate
    })
    .AddHttpMessageHandler(sp => sp.GetService<SomeCustomHandler>().CreateAuthHandler())
    .AddPolicyHandlerFromRegistry(PollyPolicyName.HttpRetry)
    .AddPolicyHandlerFromRegistry(PollyPolicyName.HttpCircuitBreaker);

Also you can define error handling policy via usage of special builders methods of Polly library. In this example policy should be predefined and stored into policy registry service.

public static IServiceCollection AddPollyPolicies(
    this IServiceCollection services, 
    Action<PollyPoliciesOptions> setupAction = null)
{
    var policyOptions = new PollyPoliciesOptions();
    setupAction?.Invoke(policyOptions);

    var policyRegistry = services.AddPolicyRegistry();

    policyRegistry.Add(
        PollyPolicyName.HttpRetry,
        HttpPolicyExtensions
            .HandleTransientHttpError()
            .WaitAndRetryAsync(
                policyOptions.HttpRetry.Count,
                retryAttempt => TimeSpan.FromSeconds(Math.Pow(policyOptions.HttpRetry.BackoffPower, retryAttempt))));

    policyRegistry.Add(
        PollyPolicyName.HttpCircuitBreaker,
        HttpPolicyExtensions
            .HandleTransientHttpError()
            .CircuitBreakerAsync(
                handledEventsAllowedBeforeBreaking: policyOptions.HttpCircuitBreaker.ExceptionsAllowedBeforeBreaking,
                    durationOfBreak: policyOptions.HttpCircuitBreaker.DurationOfBreak));

    return services;
}

Upvotes: 43

djaszczurowski
djaszczurowski

Reputation: 4523

Actually I'm not using automatic decompression but the way to achieve this is to properly register http client

services.AddHttpClient<MyCustomHttpClient>()
   .ConfigureHttpMessageHandlerBuilder((c) =>
     new HttpClientHandler()
     {
        AutomaticDecompression = System.Net.DecompressionMethods.GZip
     }
   )
   .AddHttpMessageHandler((s) => s.GetService<MyCustomDelegatingHandler>())

Upvotes: 27

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