Making a simple Web API post request

Question

I'm really struggling with making a basic post request in a url to support a tutorial on web api.

I want to do something like this in browser: http://localhost:59445/api/group/post/?newvalue=test and get the post to register. However I don't seem to be able to form the request correctly. What is the correct way to do this?

The error I receive is:

{"Message":"The request is invalid.","MessageDetail":"The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'System.String Get(Int32)' in 'twin_groupapi.Controllers.GroupController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter."}

my model:

    public class Group  
    {
     public Int32 GroupID { get; set; }
     public Int32 SchoolID { get; set; }
     public string GroupName { get; set; }
    }

routing:

public static void Register(HttpConfiguration config)
    {
        // Web API configuration and services

        GlobalConfiguration.Configuration.IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.Always;
        // Web API routes
        config.MapHttpAttributeRoutes();

        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{action}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );
    }

controller:

    //[Route("api/Group/Post")]
    [HttpPost]
    public void Post([FromUri] string NewValue)
    {

        string newstring = NewValue;

    }

Do you have another method with name post and verb as `httpget`? — Sateesh Pagolu, Dec 14 '16 at 23:35
only other verb is `// GET: api/Group [Route("api/Group/Get")] [HttpGet] public Array Get()` — oooo ooo, Dec 14 '16 at 23:37

score 6 · Accepted Answer · answered Dec 14 '16 at 23:40

Hitting a URL in your browser will only do a GET request.

You can either:

create a simple <form> with its method set to POST and form inputs to enter the values you want to send (like NewValue), OR
write some JavaScript to create an AJAX POST request using your favorite framework, OR
Use a tool like Postman to set up a POST request, invoke it, and examine the results.

score 2 · Answer 2 · edited May 23 '17 at 11:53

2

The error message is most likely coming from your Get() method.

As @StriplingWarrior said you are making a GET request while the method is marked as [HttpPost]. You can see this if you use developer tools in your browser (F12 in most modern browsers to active them).

Have a look at How do I manually fire HTTP POST requests with Firefox or Chrome?

Note: the c# convention for parameter names is camelCase with first letter being common, not capital, e.g. string newValue.

edited May 23 '17 at 11:53

Community

1
1

answered Dec 14 '16 at 23:49

tymtam

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To make this concrete from the link above, read up on the Fetch API as perhaps the simplest approach. So if you want to do a POST from the browser, just type something like the following in the browser console: `fetch('http://localhost:59445/api/group/post/?newvalue=test',{ method: 'POST'})` – Tawab Wakil Jun 04 '22 at 17:41

Making a simple Web API post request

2 Answers2