(400)尝试将简单值发布到API时出现错误请求

本文介绍了(400)尝试将简单值发布到API时出现错误请求的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有用于Web API的 LoansController

I have this LoansController for a web api

[Route("api/[controller]")] [ApiController] public class LoansController : ControllerBase { // GET api/values [HttpGet] public ActionResult<IEnumerable<string>> Get() { return new string[] { "value1", "value2" }; } // POST api/loans [HttpPost] public void Post([FromBody] string value) { } }

在PowerShell中，我可以致电

In PowerShell I can call

Invoke-WebRequest localhost:1113/api/loans -Body $postParams -Method Get

，它工作正常(我得到 value1 和 value2 )

and it works fine (I get value1 and value2)

但是当我尝试

$postParams = "{'value':'123'}" Invoke-WebRequest localhost:1113/api/loans -Body $postParams -Method Post # -ContentType 'Application/json'

我一直都在获得

Invoke-WebRequest:远程服务器返回错误:(400)错误的请求.

Invoke-WebRequest : The remote server returned an error: (400) Bad Request.

我在做什么错了?

我尝试添加 -ContentType'Application/json'，但没有区别

I tried adding -ContentType 'Application/json' but it made no difference

我想念什么?

我也尝试了 Invoke-RestMethod ，但结果相同.

I also tried Invoke-RestMethod but with the same results..

接下来，我从 value 参数中删除了 [FromBody] ，但是 value 现在以 null 的形式出现>

Next I removed [FromBody] from the value param but value now comes in as null

推荐答案

原因

这只是发生，因为您的操作方法期望HTTP请求的正文中出现简单的 string :

It just happens because your action method is expecting a plain string from HTTP request's Body:

[HttpPost] public void Post([FromBody] string value) { }

这里的普通字符串是由用"

如果您确实希望将json字符串 {'value':'123'} 发送到服务器，则应使用以下有效负载:

If you do want to send the json string {'value':'123'} to server, you should use the following payload :

POST localhost:1113/api/loans HTTP/1.1 Content-Type: application/json "{'value':'123'}"

注意:我们必须使用双引号字符串！没有"

如何修复

要发送纯字符串，只需使用以下 PowerShell 脚本: $postParams = "{'value':'123'}" $postParams = '"'+$postParams +'"' Invoke-WebRequest localhost:1113/api/loans -Body $postParams -Method Post -ContentType 'application/json'

或者，如果您想使用json发送有效载荷，则可以创建一个 DTO 来保存 value 属性:

public class Dto{ public string Value {get;set;} }

并将您的操作方法更改为:

and change your action method to be :

[HttpPost] public void Post(Dto dto) { var value=dto.Value; }

最后，您可以调用以下 PowerShell 脚本来发送请求:

Finally, you can invoke the following PowerShell scripts to send request :

$postParams = '{"value":"123"}' Invoke-WebRequest localhost:1113/api/loans -Body $postParams -Method Post -ContentType 'application/json'

这两种方法对我来说都完美无缺.

These two approaches both work flawlessly for me.