ASP.NET WebAPI: How to control string content returned to client?

Question

In WebAPI, say I return a string wrapped in an HTTP response:

return Request.CreateResponse(HttpStatusCode.BadRequest, \"Line1 \\r\\n Line2\");

Answer 1

This happens because your controller is returning JSON in which string values are quoted.

A simple solution is to parse the responseText as JSON and then you can use the value as intended:

$.ajax("/api/values/10", {
    error: function (xhr) {
        var error = JSON.parse(xhr.responseText);
        $("textarea").val(error);
    }
});

This correctly interprets the line breaks/carriage returns.

Alternatively you can specify the text/plain media type in your controller:

return Request.CreateResponse(
    HttpStatusCode.BadRequest, 
    "Line1 \r\n Line2", "text/plain");

Web API will then try and load an appropriate media type formatter for text/plain which unfortunately does not exist OOTB. You'll find one in WebApiContrib.