azure-functions - IFunctionExceptionFilter 和编写响应

Question

我正在使用 Azure 函数并尝试使用 IFunctionExceptionFilter 和 IHttpContextAccessor 编写通用异常过滤器。它有效，我可以在响应中设置 header 变量。但是，无论我尝试什么，响应主体都是空白的。

public abstract class BaseAPI : IFunctionExceptionFilter
{
    private readonly IHttpContextAccessor httpContextAccessor;

    protected BaseAPI(IHttpContextAccessor httpContextAccessor)
    {
        this.responseValidator = responseValidator;
    }

    public async Task OnExceptionAsync(FunctionExceptionContext exceptionContext, CancellationToken cancellationToken)
    {
        httpContextAccessor.HttpContext.Response.StatusCode = StatusCodes.Status500InternalServerError;
        httpContextAccessor.HttpContext.Response.Headers.Append("MyHeader", "Foo"); // this works and appears
        await httpContextAccessor.HttpContext.Response.WriteAsync("Some text"); // this is not shown in the response
    }
}

我必须做什么才能让 body react 出现？我试过直接使用 Response.Body，但没有任何区别。

Answer 1

我只是在寻找合适的 OnExceptionAsync 实现时偶然发现了这个问题。代码中唯一缺少的是响应内容类型和长度。

    public async Task OnExceptionAsync(FunctionExceptionContext exceptionContext, CancellationToken cancellationToken)
    {
            var text = "Some text"; // text variable
            httpContextAccessor.HttpContext.Response.StatusCode = StatusCodes.Status500InternalServerError;
            httpContextAccessor.HttpContext.Response.ContentType = "text/html; charset=UTF-8"; // Missing part
            httpContextAccessor.HttpContext.Response.Headers.Append("MyHeader", "Foo");
            await httpContextAccessor.HttpContext.Response.WriteAsync(text);
            httpContextAccessor.HttpContext.Response.ContentLength = text.Length; // Missing part
    }

已在 Firefox、Chrome 和 Edge 中测试。希望对您有所帮助。

更新，来自@ChrisHG，缺少一个字符串

httpContextAccessor.HttpContext.Response.CompleteAsync()

或者，我现在使用的字符串。

await response.WriteAsync(errorMessage, Encoding.UTF8, cancellationToken);