“IServiceCollection”不包含“AddPolicyHandler”的定义答案

【问题标题】：'IServiceCollection' does not contain a definition for 'AddPolicyHandler'“IServiceCollection”不包含“AddPolicyHandler”的定义
【发布时间】：2022-01-03 20:28:17
【问题描述】：

我在 VS2019 中的 .NET 5.0 框架 Azure 持久功能项目中遇到错误

“IServiceCollection”不包含“AddPolicyHandler”的定义，并且最佳扩展方法重载“PollyHttpClientBuilderExtensions.AddPolicyHandler(IHttpClientBuilder, IAsyncPolicy)”需要“IHttpClientBuilder”类型的接收器

.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net5.0</TargetFramework>
    <AzureFunctionsVersion>v3</AzureFunctionsVersion>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="IdentityModel" Version="4.2.0" />
    <PackageReference Include="Microsoft.ApplicationInsights.WorkerService" Version="2.15.0" />
    <PackageReference Include="Microsoft.Azure.Functions.Extensions" Version="1.1.0" />
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.DurableTask" Version="2.5.1" />
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.ServiceBus" Version="4.3.0" />
    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="5.0.0" />
    <PackageReference Include="Microsoft.Extensions.Http" Version="3.1.0" />
    <PackageReference Include="Microsoft.Extensions.Http.Polly" Version="3.1.0" />
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="3.0.13" />
  </ItemGroup>
  <ItemGroup>
    <None Update="host.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Update="local.settings.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
      <CopyToPublishDirectory>Never</CopyToPublishDirectory>
    </None>
  </ItemGroup>
</Project>

Startup.cs

using Microsoft.Azure.Functions.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection;
using Polly;
using Polly.Extensions.Http;
using System;
using System.Net.Http;
namespace Itel.DeliveryOrchestration
{
    public class Startup : FunctionsStartup
    {
        public override void Configure(IFunctionsHostBuilder builder)
        {
            builder.Services.AddHttpClient()
                .AddPolicyHandler(GetRetryPolicy());
        }

        private IAsyncPolicy<HttpResponseMessage> GetRetryPolicy()
        {
            return HttpPolicyExtensions 
                .HandleTransientHttpError()
                .OrResult(msg => msg.StatusCode == System.Net.HttpStatusCode.NotFound)
                .WaitAndRetryAsync(2, retryAttempt => TimeSpan.FromSeconds(Math.Pow(2, retryAttempt)));
        }

    }
}

【问题讨论】：

错误是正确的source AddHttpClient 没有参数返回IServiceCollection 而AddPolicyHandler 适用于IHttpClientBuilder。您将需要使用命名客户端
@Nkosi 谢谢。现在看起来很傻:)

标签： .net-core azure-functions .net-5 azure-durable-functions

【解决方案1】：

在 cmets 中发布 @Nkosi 提供的建议作为答案，以便对面临类似问题的其他社区成员有所帮助。

AddHttpClient 不带参数返回IServiceCollection，而AddPolicyHandler 适用于IHttpClientBuilder。您将需要使用命名客户端

public static IServiceCollection AddHttpClient(this IServiceCollection services)
{
    if (services == null)
    {
        throw new ArgumentNullException(nameof(services));
    }

    //...

参考源码HttpClientFactoryServiceCollectionExtensions

【讨论】：