创建Controller调用HttpPost时遭遇415 Unsupported Media Type错误求助

我正尝试创建一个Controller，用于将类实例添加至SQL数据库，但调用HttpPost接口时持续出现HTTP 415错误，错误详情如下：

Unhandled exception rendering component: {"type":"https://tools.ietf.org/html/rfc7231#section-6.5.13","title":"Unsupported Media Type","status":415,"traceId":"00-f30954ed2136f9135eeb829d54578d45-69a58efb9fadfcc2-00"}

at blazorTestApp.Client.Repositories.AuthorsRepo.AddAuthor(Authors Author)
   at blazorTestApp.Client.Pages.Authors.AddAuthor.OnSubmit()
   at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
   at Microsoft.AspNetCore.Components.Forms.EditForm.HandleSubmitAsync()
   at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

Controller代码 #

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using blazorTestApp.Shared.Entities;
using Microsoft.AspNetCore.Mvc;

namespace blazorTestApp.Server.Controllers
{
    [ApiController]
    [Route("api/[controller]")]
    public class AuthorsController : ControllerBase
    {
        private readonly Database DB;
        public AuthorsController(Database DB)
        {
            this.DB = DB;
        }

        [HttpPost]
        public async Task<ActionResult<int>> Post(Authors Author)
        {
            DB.Add(Author);
            await DB.SaveChangesAsync();
            return Ok();
        }
    }
}

Http服务文件 #

namespace blazorTestApp.Client.Classes_FE
{
    public class HttpService : IHttpService
    {
        private readonly HttpClient httpClient;
        public HttpService(HttpClient httpClient)
        {
            this.httpClient = httpClient;
        }

        public async Task<HttpResponse<object>> POST<T>(string url, T data)
        {
            var JsonData = JsonSerializer.Serialize(data);
            var StringContent = new StringContent(JsonData, Encoding.UTF8, "applicaiton/json");
            var ResponseMessage = await httpClient.PostAsync(url, StringContent);
            return new HttpResponse<object>(null, ResponseMessage, ResponseMessage.IsSuccessStatusCode);
        }
    }
}

该文件继承自仅包含上述POST方法的接口，该接口已注入至仓储类中。

发起Http请求的仓储类 #

namespace blazorTestApp.Client.Repositories
{
    public class AuthorsRepo
    {
        private IHttpService httpService;
        private string url = "api/Authors";
        public AuthorsRepo(IHttpService httpService)
        {
            this.httpService = httpService;
        }

        public async Task AddAuthor(Authors Author)
        {
            var response = await httpService.POST(url, Author);
            if(!response.Success)
            {
                throw new ApplicationException(await response.GetBodyString());
            }
        }
    }
}

调用AddAuthor方法的页面文件 #

@page "/Authors/Add"
@inject AuthorsRepo authorRepo
@inject NavigationManager NavMan

@code
{
    public Authors Author {get; set;} = new Authors();
    public async Task OnSubmit()
    {
        //Unrelated code
        await authorRepo.AddAuthor(Author);
        NavMan.NavigateTo("Authors");
    }
}

问题原因与修复方案 #

HTTP 415错误的核心原因是请求的Content-Type拼写错误：
在HttpService的POST方法中，你将application/json误写为applicaiton/json（缺少一个字母o），导致服务器无法识别请求的媒体类型。

1. 核心修复

修正Content-Type的拼写错误：

var StringContent = new StringContent(JsonData, Encoding.UTF8, "application/json");

2. 额外优化建议

• 为Controller的Post方法添加[FromBody]特性，明确指定从请求体绑定参数，避免潜在的参数绑定问题：

  [HttpPost]
  public async Task<ActionResult<int>> Post([FromBody] Authors Author)
  {
      DB.Add(Author);
      await DB.SaveChangesAsync();
      return Ok();
  }
  

• 使用HttpClient.PostAsJsonAsync简化代码，该方法会自动完成序列化并设置正确的Content-Type，无需手动创建StringContent：

  public async Task<HttpResponse<object>> POST<T>(string url, T data)
  {
      var ResponseMessage = await httpClient.PostAsJsonAsync(url, data);
      return new HttpResponse<object>(null, ResponseMessage, ResponseMessage.IsSuccessStatusCode);
  }
  

内容的提问来源于stack exchange，提问作者Saucter