ILogger 通过 Azure Function 2.x 的 Http 触发函数的构造函数注入

问题描述

ILogger 可以注入到函数参数中，比如下面的Token方法.

ILogger can be injected to function parameter, like Token method below.

但是，注入到构造函数参数log时，出现如下错误.

However, the error below occurred when it is injected to constructor parameter log.

[07/03/2019 17:15:17] 执行令牌"(失败，id=4e22b21f-97f0-4ab4-8f51-8651b 09aedc8) [07/03/2019 17:15:17]Microsoft.Extensions.DependencyInjection.Abstractions:无法解析Microsoft.Extensions.Logging.ILogger"类型的服务，而尝试激活功能".

[07/03/2019 17:15:17] Executed 'Token' (Failed, Id=4e22b21f-97f0-4ab4-8f51-8651b 09aedc8) [07/03/2019 17:15:17] Microsoft.Extensions.DependencyInjection.Abstractions: Una ble to resolve service for type 'Microsoft.Extensions.Logging.ILogger' while attempting to activate 'Functions'.

ILogger 可以注入到下面的Token 函数参数中.但是上面的错误是注入到构造函数参数log的时候出现的.

ILogger can be injected to Token function parameter below. But the error above occurred when it is injected to constructor parameter log.

public class Functions
{
    private HttpClient _httpClient;
    private IAppSettings _appSettings;
    private ILogger _log;

    public Functions(HttpClient httpClient, IAppSettings appSettings  //working for these two
      , ILogger log  //not working, errors
    )
    {

        _log = log;
    }

    [FunctionName("Token")]
    public async Task<IActionResult> Token(
        [HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = "Token")]
        HttpRequest httpRequest,
        ILogger log)
    {

    }
}

下面的依赖注入

[assembly: WebJobsStartup(typeof(Startup))]
namespace MyApp
{
    public class Startup : IWebJobsStartup
    {
        public void Configure(IWebJobsBuilder builder)
        {
            builder.Services.AddHttpClient();
            builder.Services.AddTransient<IAppSettings, AppSettings>();     
             //builder.Services.AddLogging();  //not working
           //builder.Services.AddSingleton<ILogger>() //not working
        }
}

视觉工作室 2017

Visual studio 2017

推荐答案

我也遇到了这个问题.我可以通过调用 AddLogging():

I had this problem as well. I was able to fix it by calling AddLogging():

[assembly: WebJobsStartup(typeof(Startup))]
namespace MyApp
{
    public class Startup : IWebJobsStartup
    {
        public void Configure(IWebJobsBuilder builder)
        {
            builder.Services.AddHttpClient();
            builder.Services.AddTransient<IAppSettings, AppSettings>();     
            builder.Services.AddLogging();
        }
}

然后，在 Azure 函数中，我必须传递 ILoggerFactory 而不是 ILogger 并从loggerFactory:

And then, in the Azure Function, I had to do pass a ILoggerFactory instead of an ILogger and get the ILogger instance from the loggerFactory:

public class Functions
{
    private HttpClient _httpClient;
    private IAppSettings _appSettings;
    private ILogger _log;

    public Functions(HttpClient httpClient, IAppSettings appSettings, ILoggerFactory loggerFactory)
    {
        _log = loggerFactory.CreateLogger<Functions>();
    }

    [FunctionName("Token")]
    public async Task<IActionResult> Token(
        [HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = "Token")]
        HttpRequest httpRequest)
    {
           // No need to keep getting the ILogger from the Run method anymore :)
    }
}

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