POST JSON from Angular frontend to ASP.NET backend

Question

I would like to send data (originally arrays) as JSONs to my MVC-controller in the backend. I was trying this:

my-ng-service.ts

//...
setEmployees(employees) {
    var employeesJSON = JSON.stringify(employees);
    console.log(employeesJSON); //working
    this.http.post('/api/employees', employeesJSON).subscribe();
}
//...

EmployeesController.cs

//...
[Route("api/[controller]")]
[HttpPost]
public void Post(JsonResult data)
{
    Console.Write("hallo: " + data); //error see below
}
//...

I don't know how I have to write my controller. Can anybody help me?

Current error:

System.Argument.Exception: Type 'Microsoft-AspNetCore.Mvc:JsonResult' does not have a default constructor Parameter name: type

Thanks in forward!

Why not just use public JsonResult Post(string data)? Never use JsonResult as action method argument because it used to return JSON data. — Tetsuya Yamamoto
– Tetsuya Yamamoto, Commented Nov 21, 2017 at 8:55

CodeCaster · Accepted Answer · 2017-11-21 08:27:31Z

4

JsonResult is a type you use to output JSON from an action method, not as input parameter.

See ASP.NET Core MVC : How to get raw JSON bound to a string without a type? and ASP.NET MVC Read Raw JSON Post Data: you can change the parameter type to dynamic or JObject, or you can manually read the request body as string.

But you should really reconsider this. Creating a model so you can bind your model strongly-typed is a matter of seconds work, and will benefit you greatly in the future.

answered Nov 21, 2017 at 8:27

CodeCaster

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2 Comments

dafna Over a year ago

That's now working with JSON. Thanks a lot! But you're right. To use my model (already existing) that would be better. Do you want to give me a hint how I have to do this? I created this method to get and set my MVC-modelconsisting of id and name: public class EmployeeViewModel { public IEnumerable<Employees> Employees { get; set; } }

CodeCaster Over a year ago

You just change the parameter type to EmployeeViewModel.

Ashiqur Rahman Emran · Accepted Answer · 2017-11-21 08:28:00Z

1

Actually write the model name that you want to get from http request

[Route("api/[controller]")]
    [HttpPost]
    public void Post(YourJsonModel ModelObject)
    {
        Console.Write("hallo: " + data); //error see below
    }

answered Nov 21, 2017 at 8:28

Ashiqur Rahman Emran

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2 Comments

CodeCaster Over a year ago

But then you have to have a model.

Ashiqur Rahman Emran Over a year ago

Yeah If i dont have any model then jobject and dynamic is alright either we can grab the value from Request also

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