WebAPI Get autogenerated ID of a just created (posted) record

Question

Good afternoon,
I have a web API running just fine and a Xamarin forms app on top of it.
There I want to create 1:N relation which is fine in the model but I have the following problem:
(I don't want to post all the code here so I bring it down to the problem).
Model Header
public long header_Id {get;set;}
...several other fields

Model Details
public long details_Id {get;set;}
public long header_Id {get;set;}
....several other fields

The fields header_Id and details_Id are auto-generated as identity-fields in Azure SQL Server

PROBLEM:
I post the header model with "response = await client.PostAsync(uri, content);"
Record is created fine.
BUT now I need the header_Id to create my 1:N Details records.
How can I get the Id of the just created record?

I cannot use any SQL-Command here because as I have an WEBAPI between the App and the SQL-Server I cannot execute SQL queries directly against the database.

Answer 1

Solved it myself :)

After PostAsync() I have to read based on the response from the post. Then I can deserialize to my model and return this to the original function.

Here is my code in case somebody needs it:

response = await client.PostAsync(uri, content);
var feedback = await response.Content.ReadAsStringAsync();
YOURMODEL results =    JsonConvert.DeserializeObject<YOURMODEL>(feedback);
return results;