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The input was not valid .Net Core Web API

I am facing a weird issue and almost spent 4 hours with no luck.

I have a simple Web API which I am calling on form submit.

API-

// POST: api/Tool [HttpPost] public void Post([FromBody] Object value) {     _toolService.CreateToolDetail(Convert.ToString(value)); } 

HTML-

<!DOCTYPE html> <html> <body>  <h2>HTML Forms</h2> <form name="value" action="https://localhost:44352/api/tool" method="post">   First name:<br>   <input type="text" id="PropertyA" name="PropertyA" value="Some value A">   <br>   Last name:<br>   <input type="text" id="PropertyB" name="PropertyB" value="Some value B">   <br><br>   <!--<input type="file" id="Files" name="Files" multiple="multiple"/>-->   <br><br>   <input type="submit" value="Submit">    </form> </body> </html> 

When I hit the submit button I get below error-

{"":["The input was not valid."]} 

Configurations in Startup class-

public void ConfigureServices(IServiceCollection services) {     services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);     services.AddSingleton<IConfiguration>(Configuration); }  public void Configure(IApplicationBuilder app, IHostingEnvironment env) {     if (env.IsDevelopment())     {         app.UseDeveloperExceptionPage();     }     else     {         app.UseHsts();     }      app.UseHttpsRedirection();     app.UseMvc(); } 

This only happens for POST request. GET request works fine. Same issue when testing in Postman REST client. Any help please? Please let me know if I can provide more details.

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Display name Avatar asked Jul 06 '18 13:07

Display name


2 Answers

Don't use FromBody. You're submitting as x-www-form-urlencoded (i.e. standard HTML form post). The FromBody attribute is for JSON/XML.

You cannot handle both standard form submits and JSON/XML request bodies from the same action. If you need to request the action both ways, you'll need two separate endpoints, one with the param decorated with FromBody and one without. There is no other way. The actual functionality of your action can be factored out into a private method that both actions can utilize, to reduce code duplication.

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Chris Pratt Avatar answered Sep 21 '22 01:09

Chris Pratt


I just worked through a similar situation here; I was able to use the [FromBody] without any issues:

public class MyController : Controller {    [HttpPost]    public async Task<IActionResult> SomeEndpoint([FromBody]Payload inPayload)    {    ...    } }  public class Payload {    public string SomeString { get; set; }    public int SomeInt { get; set; } } 

The challenge I figured out was the ensure that the requests were being made with the Content-Type header set as "application/json". Using Postman my original request was returned as "The input was not valid." Adding the Content-Type header fixed the issue for me.

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Adam Schumph Avatar answered Sep 22 '22 01:09

Adam Schumph