Azure Function Request POST Body Encoding - encoding

Question

I'm wondering whether encoding is something I have to explicitly handle in an Azure function (v3) triggered by an http POST.
For example... which approach is correct (s1, s2, or s3):
[Function("MyFancyFunction")]
public async Task<HttpResponseData> Run(
[HttpTrigger(AuthorizationLevel.Anonymous, "post")] HttpRequestData req,
FunctionContext executionContext)
{
// What charset/encoding will be used if not specified?
var s1 = req.ReadAsString();
// Surely it can't be save to assume UTF8?
var s2 = req.ReadAsString(Encoding.UTF8);
// Use the charset of the first content-type
var ct = MediaTypeHeaderValue.Parse(req.Headers.GetValues("content-type").First());
var s3 = req.ReadAsString(ct.Encoding);
...
}
Thanks!

Answer 1

I put together a simple test function and simple http POST console app.
The console app explicitly encodes the POST payload as Win-1252 (only chosen because it has characters from 0-255). The payload includes a 0x0080 character (utf-8 start sequence) which should cause problems if not decoded using the appropriate encoding.
Here's what the POST payload program looks like:
var client = new HttpClient();
var req = new HttpRequestMessage(HttpMethod.Post, " http://localhost:7071/api/Function1");
req.Content = new StringContent("d\u0080d");
req.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/json");
req.Content.Headers.ContentEncoding.Add("win-1252");
client.Send(req);
The test function looks like:
[Function("Function1")]
public static HttpResponseData Run([HttpTrigger(AuthorizationLevel.Anonymous, "get", "post")] HttpRequestData req,
FunctionContext executionContext)
{
var s1 = req.ReadAsString(); // s1 == "d\u0080d"... yippie!
var response = req.CreateResponse(HttpStatusCode.OK);
return response;
}
The end result is that YES Azure functions will pay attention to a content-type's charset instruction and use the appropriate Encoding.

Answer 2

which approach is correct (s1, s2, or s3)
Below is the sample code which I used in my environment for encoding data and it worked for me rather than these 3 approaches I suggest to use the below given code.
public static async Task<string> Run(
[HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = null)] HttpRequest req,
ILogger log)
{
log.LogInformation("SendMessage function requested");
string body = string.Empty;
using (var reader = new StreamReader(req.Body, Encoding.UTF8))
{
body = await reader.ReadToEndAsync();
log.LogInformation($"Message body : {body}");
}
log.LogInformation($"SendMessage processed.");
return body;
}
And here is the Output with the Encoded Data