Return JSON from Web API that makes asynchronous call to Odata endpoint

Question

I am building a Web API which makes a asynchronous call to the Odata endpoint. The odata endpoint returns JSON, and I am trying to return the same JSON from the Web API too. Since I am calling the Odata endpoint asynchronously I am using Task as return type my API method but I want to return them as JSON and I am not sure how I can do that.Below is my code

   public async Task<string> GetEmployee(string instance)
    {
       .....
        EmployeeDTO.RootObject returnObj = new EmployeeDTO.RootObject();
        var responsedata = "";
        try
        {
        using (var client_Core = new HttpClient())
            {
               ....
                string core_URL = BaseURL_Core+URL_instance;
                var response = client_Core.GetAsync(core_URL).Result;

                responsedata = await response.Content.ReadAsStringAsync();
              }
        }
        catch (Exception ex)
        {
            throw ex;
        }
        return responsedata;

Currently it returns like

<string xmlns="http://schemas.microsoft.com/2003/10/Serialization/">
 {
       "@odata.context":"https://science.com/odata/$metadata#EMPLOYEE",
"value":[
       { 
        "Id":5000004, 
        "Name":"Account", 
        "Barcode":"EM1"
       }]
    }
 </string>

I am trying to avoid the string tag around the JSON response. How acn we do that

What's the content type you requested? Web API's responses are converted to the requested format if they're objects and one of the requested formats is supported. — Chayim Friedman, Aug 20 '18 at 12:12
If the service only returns xml then you could simply parse the response as xml and extract the json from the `` element. Incidentally, you don't need to block with `.Result` if you are in an async method, you should `await`. Also [try not to new up an `HttpClient` for each request](https://aspnetmonsters.com/2016/08/2016-08-27-httpclientwrong/) — Crowcoder, Aug 20 '18 at 12:29
@Crowcoder Thanks for you suggestion on the HttpClient I will fix that. I am not doing anyother manipulation in my API and the other application that will call my API can only consume JSON. How can I have a JSON response. Should I change the `Task` anyother format? — trx, Aug 20 '18 at 12:50
@ChayimFriedman I havenot added the content type in my API, where should I be adding that? — trx, Aug 20 '18 at 12:54
I think that the default is XML. Try to set the content type to `application/json`. — Chayim Friedman, Aug 20 '18 at 12:55
If it won't work, see https://stackoverflow.com/questions/18266952/asp-net-web-api-returning-xml-instead-of-json. This is a similar problem. — Chayim Friedman, Aug 20 '18 at 13:02

score 1 · Accepted Answer · answered Aug 20 '18 at 12:58

1

I hope the API can return JSON and it is just a matter of changing the Content-Type as suggested by Chayim.

But if it will only return xml, you could do this:

...
string core_URL = BaseURL_Core+URL_instance;
var response = await client_Core.GetAsync(core_URL);
string xml = await response.Content.ReadAsStringAsync();
System.Xml.Linq.XDocument doc = System.Xml.Linq.XDocument.Parse(xml);
responsedata = doc.Root.Value;
...

answered Aug 20 '18 at 12:58

Crowcoder

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If I am not using `.result` in `await client_Core.GetAsync(core_URL)` I am getting error in the below line like `'System.Threading.Tasks.Task' does not contain a definition for 'Content' and no extension method 'Content' accepting a first argument of type 'System.Threading.Tasks.Task' could be found (are you missing a using directive or an assembly reference?)` – trx Aug 20 '18 at 19:37
Are you sure you are using `await`? That is the error you would get if you omitted the `await` keyword. – Crowcoder Aug 20 '18 at 19:52
@trx Thank you. You did **not** add `await` to `client_Core.GetAsync(core_URL)` – Crowcoder Aug 20 '18 at 20:20
Getting an error while Parsing `$exception {"Data at the root level is invalid. Line 1, position 1."} System.Exception {System.Xml.XmlException}` – trx Aug 20 '18 at 20:26
@trx That code worked for me based on the xml in your original question. I see you asked another question and your system has now been modified so I don't know the current state of the response. What exactly is the string value of `response.Content.ReadAsStringAsync()` now? – Crowcoder Aug 20 '18 at 20:29

Return JSON from Web API that makes asynchronous call to Odata endpoint

1 Answers1