Postman unable to set values to dictionary parameter for C# web api

Question

I have below code written to test for reading the dictionary key and values from Postman.

C# web api method:

[OperationContract]
[WebInvoke(Method = "POST", UriTemplate = "Service/testdictionary",
BodyStyle = WebMessageBodyStyle.WrappedRequest)]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public void testdictionary(Dictionary<string,object> data)
{
if(data != null)
{
string str1 = data["a1"].ToString();
string str2 = data["a2"].ToString();
string str3 = data["a3"].ToString();
}
}

Postman input Body:(raw and JSON(application/json))

{
"data": {
"a1": "b1",
"a2": "b2",
"a3": "b3"
}
}

How am I calling the method from Postman:

Postman Call

What is the issue: Whenever I am trying to assign dictionary object data from the postman, in C# code it is getting assigned as an empty dictionary.

What is required: I want to read a dictionary element from postman to my API code.

Possible duplicate of [POST json dictionary](https://stackoverflow.com/questions/4710729/post-json-dictionary) — Adrian, Dec 21 '18 at 15:19
Thanks for Sharing !! Solution provide by @Adriani6 is suitable for MVC. if you have something which will help me then post. — Pratik Navagekar, Dec 21 '18 at 17:00
@PratikNavagekar, how to call your method? please share in the question — Divyang Desai, Dec 21 '18 at 17:39
@Div, add the image file for postman method call. I am trying to set dictionary in my web api from Postman call. — Pratik Navagekar, Dec 22 '18 at 13:40

Crowcoder · Answer 1 · 2018-12-22T14:55:44.007

Your items are not data["a1"], data["a2"], etc. You have a dictionary of ONE item whose key is "data", so it is data["data"]. Your value for that one item is an object with a1, a2 and a3 properties. Not sure what that works out to in your WCF app but in Web API it is a JToken from the Newtonsoft Json.Net library.

If you want a Dictionary with keys a1, a2, a3 you need to adjust your JSON body to exclude the "data" level:

{
"a1": "b1",
"a2": "b2",
"a3": "b3"
}

UPDATE

If you are unable to change the JSON structure for some reason, you could create a class with a data property that is of Type Dictionary<string,object>:

public class TheData
{
    public Dictionary<string, object> data {get;set;}
}

Then your api method would take a TheData type instead of Dictionary<string,object>:

public void testdictionary(TheData _data)
{
    ...

and your code would access the dictionary like:

string d1 = _data.data["a1"].ToString(); // d1 == "b1"

Thanks for Sharing the Solution unfortunately the solution didnt work for dictionary. Not sure whether its a limitation for WCF service. But I have managed to get idea from your solution. Posting my Solution below. — Pratik Navagekar, Dec 23 '18 at 17:39

score 0 · Answer 2 · answered Dec 22 '18 at 15:41

0

Try this.

i tried! it works fine.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;

namespace StackOverFlowProblemWebApi.Controllers
{
    public class TestController : ApiController
    {
        [HttpPost]
        public IHttpActionResult TestDictionary([FromBody]Dictionary<string,object> data)
        {
            if (data != null)
            {
                string string1 = data["a1"].ToString();
                string string2 = data["a2"].ToString();
                string string3 = data["a3"].ToString();

                return Ok("Data Recieved."); // When the data is successfully recieved.
            }
            else
                return BadRequest("Data is not received.");
        }
    }
}

Look! did you see that: the data is received. ...

answered Dec 22 '18 at 15:41

Rehan Shah

1,505
12
28

Yes, but that is not the same JSON structure that OP is sending. – Crowcoder Dec 22 '18 at 16:10
He is using WCF not webapi! – Prashant Pimpale Dec 23 '18 at 01:55
@Rehan.S Yes I am using WCF and the solution provided by you works fine with MVC api's. – Pratik Navagekar Dec 23 '18 at 17:40
@Pratik Navageker... Sorry for my answer....the reason is that,i was wondering that you asking about web api and mvc.... – Rehan Shah Dec 23 '18 at 17:56

score 0 · Answer 3 · answered Dec 23 '18 at 17:54

Managed to solve my problem as a workaround, can say similar kind of dictionary.

What's the Solution: Use class object instead of dictionary.

Here is My Solution:

I add a class, similar structure as dictionary I wanted.(Only thing is I have to code extra line of code to declare class with Keys , which i was avoiding earlier)

Here is my code from web api:

    public class mydictionary
    {
        public string a1 { get; set; }
        public string a2 { get; set; }
        public string a3 { get; set; }
    }

    [OperationContract]
    [WebInvoke(Method = "POST", UriTemplate = "Service/testdictionary",
    BodyStyle = WebMessageBodyStyle.WrappedRequest)]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public string testdictionary(mydictionary data)
    {
        if (data != null)
        {
            string str1 = data.a1.ToString();
            string str2 = data.a2.ToString();
            string str3 = data.a3.ToString();
            return "success".ToString();
        }
       else
        {
            return "unsuccess".ToString();
        }

    }

Here is my Postman input and Output: Postman Screen Shot

score 0 · Answer 4 · answered Jul 20 '19 at 18:34

0

In my case, it worked in this format ActionParam = [{ Key: 'orderId', Value: '200' }]; 'ActionParam' is a dictionary property in a model and also tested on WCF.

answered Jul 20 '19 at 18:34

ni3.net

377
4
14

Postman unable to set values to dictionary parameter for C# web api

4 Answers4