Post value always null between Python request and ASP.Net Core API - asp.net-core

Question

I have some simple Python
import requests
response = requests.post(url+'users/', data = 'hallo')
And a simple ASP.Net Core API
public void Post(string value)
{
var newUser = JsonConvert.DeserializeObject<User>(value);
// [...]
}
When I breakpoint the C# code the incoming parameter 'value' is always null. I have tried sending JSON instead of a simple string, setting the headers to 'text/plain', 'application/json', or 'application/x-www-form-urlencoded' in Python but the result is the same. I have tried decorating the parameter [FromBody] in the ASP.Net Core API, but then I get a 400 error ("The input was invalid").
What am I missing?
(EDIT. Here is a hacky fix, definitely not an answer, but it may help people see what's wrong.
public void Post(string value)
{
Request.EnableRewind();
var body = "";
using (var reader = new StreamReader(Request.Body))
{
Request.Body.Seek(0, SeekOrigin.Begin);
body = reader.ReadToEnd();
}
value = body;
var newUser = JsonConvert.DeserializeObject<User>(value);
// [...]
}
Then value is set correctly. But if the value is sitting there in the body of the post, it is frustrating that using [FromBody] results in a 400 error.)

Answer 1

Hi dumbledad I had this same issue, I guess you would have solved it but I wanted to post the solution here.
I had to send the data to params instead of data.
So on the Python side:
payload = {"type": "2"}
myheaders={'Content-type':'application/json', 'Accept':'application/json'}
r = requests.post(url=myurl,headers=myheaders, params=payload)
On the c# side:
[Route("MyFunction")]
[HttpPost]
public ActionResult GetOpenFootball_(string type){}
This mapped the value "2" to the string parameter called "type".
EDIT
I managed to get objects through the [From Body] tag in this way:
I changed the header to:
_headers = {'Content-type': 'application/json', 'Accept': 'text/plain'}
I put my parameters into a json such as:
jsondata = {"username":"selzero"}
Then I plugged that into the json property in request like:
r = requests.post(url=_url, headers=_headers,json=jsondata)
This works, MVC controller [FromBody] likes it.

Answer 2

If you make your request like this:
response = requests.post(url, data={'value' : 'hallo'})
Then this will associate 'hallo' with the method-parameter value:
[HttpPost]
public void Post(string value)
{
Console.WriteLine(value);
}
If you need to send more data, you could also wrap your request in an object and fetch it by model-binding. See more here: Model Validation in ASP.NET Web API. It looks like that's what you're attempting to do anyways here:
var newUser = JsonConvert.DeserializeObject<User>(value);
You can achieve this automatically like this:
response = requests.post(url, json={ 'FirstName' : 'john', 'LastName' : 'doe' })
Notice the use of json=. And in your controller:
public class User {
public string FirstName { get; set; }
public string LastName { get; set; }
}
[HttpPost]
public void Post([FromBody] User user)
{
Console.WriteLine(user.FirstName);
Console.WriteLine(user.LastName);
}
// Outputs:
// john
// doe