How to additionally include File as response of WebAPI

Question

My current web API already responding JSON data as below.

public HttpResponseMessage GetFieldInfo()
        {
  //....  
return Ok(GetFieldsInstance());  //GetFieldsInstance returning with DTO class instance.
}

Now, I need to include, file along with JSON response. I could not find any link which shows, how to include filestream and JSON in single response.

For file stream, it will work as below but, not able to find way, how to include JSON object property with filestream.

result = Request.CreateResponse(HttpStatusCode.OK);
                result.Content = new StreamContent(new FileStream(localFilePath, FileMode.Open, FileAccess.Read));
                result.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
                result.Content.Headers.ContentDisposition.FileName = "FieldFile";

Answer 1

You can covert (serialize) the file to a base64 string and include it as a property in the JSON response.

public IHttpActionResult GetFieldInfo() {
    //...

    var model = new { 
        //assuming: byte[] GetBinaryFile(...)
        data = Convert.ToBase64String(GetBinaryFile(localFilePath)), 
        result = "final",
        //...other properties...
    };

    return Ok(model);
}

The client would then need to convert (desrialize) the base64 string back to your desired file to be used as desired.

Take note that depending on the size of the file it can drastically increase the size of the response and the client should take that into consideration.