Relaying JSON has escaped double-quotes

Question

I have a very simple C# Azure Function created in VS running locally that wraps the call to a 3rd party REST API for simplicity (acts as a proxy, but not an Azure Function Proxy). All the function does after validating the supplied parameters is invoke the 3rd party REST API and directly return the results (JSON response) if the call is successful.

HttpResponseMessage response = await _httpClient.PostAsync( requestUri, content );

if ( response.IsSuccessStatusCode )
{
    var jsonResponseBody = await response.Content.ReadAsStringAsync();
    return req.CreateResponse( HttpStatusCode.OK, jsonResponseBody, "application/json" );
}

The resulting JSON that I get from invoking my Azure Function in Postman is similar to the following (internal double-quotes are string escaped):

"{\"Id\":\"0\",\"FirstName\":\"firstname\",\"LastName\":\"lastname\"}"

What could be causing this escaping to occur and how can I get rid of it?

Are you seeing the backslashes in the inspector? or actually in the HTML received data — BugFinder, Jan 24 '18 at 14:18
For Azure In Process v4 Function you can return ContentResult. See https://stackoverflow.com/a/75798884/675079 — Arjen den Hartog, Mar 21 '23 at 09:05

score 4 · Accepted Answer · answered Jan 24 '18 at 14:36

CreateResponse will serialize whatever you give to it as JSON (or XML, if you ask to). If you give it string, it will wrap this string into extra "" to make it valid JSON (or in an XML tag), like in all HelloWorld examples. So

req.CreateResponse(HttpStatusCode.OK, "Hello " + name)

returns HTTP response "Hello User", because Hello User won't be valid JSON. The function doesn't care that your string is already a valid JSON.

To return string content as-is, you need to ask for that explicitly:

var response = req.CreateResponse(HttpStatusCode.OK);
response.Content = new StringContent(jsonResponseBody, Encoding.UTF8, "application/json");
return response;

Relaying JSON has escaped double-quotes

1 Answers1