Using the Function interface to set a handler function in C#
You can set a handler function in C# without needing to inherit from SDK classes.
Warning
The handler method must be public, be named FunctionHandler, and have one input parameter.
Example of a valid handler:
public class Handler {
public String FunctionHandler(int i) {
return i.ToString();
}
}
Example of an invalid handler:
// Handler should not have any type parameters
public class Handler<T> {
public int FunctionHandler(T i) {
return 2;
}
}
You can use any classes as input and return types.
Note
Fields of these classes may have any access modifiers. If a field is non-public, it requires a public getter method. Otherwise, the field won't be included in the response.
Examples
HTTP request structure output
The following function receives a request with two fields (a string and a number) and returns a formatted string with the provided data.
Warning
To invoke the function, use the Yandex Cloud CLI or an HTTP request with the ?integration=raw parameter.
The Request.cs file:
public class Request {
public String message { get; set; }
public int number { get; set; }
}
The Handler.cs file:
public class Handler {
public String FunctionHandler(Request r) {
// at this stage, the r variable already stores the parsed request
return $"Message is {r.message}, number is {r.number}";
}
}
Example of input data:
{
"message": "Hello",
"number": 24
}
Returned string:
Message is Hello, number is 24
Parsing an HTTP request
The function is invoked via an HTTP request with a username, logs the request method and body, and returns a greeting.
Warning
Do not use ?integration=raw to invoke this function. If you do, the function will not get any data about the original request’s methods, headers, or parameters.
The Request.cs file:
public class Request {
public String httpMethod { get; set; }
public String body { get; set; }
}
The Response.cs file:
public class Response {
public int statusCode { get; set; }
public String body { get; set; }
public Response(int statusCode, String body) {
this.statusCode = statusCode;
this.body = body;
}
}
The Handler.cs file:
using System.Text.Json;
public class Handler {
public Response FunctionHandler(Request r) {
var method = r.httpMethod;
var body = r.body;
Console.WriteLine($"{method}, {body}");
using var jsonDoc = JsonDocument.Parse(body);
var root = jsonDoc.RootElement;
// Here, the name parameter is retrieved from the request body.
// If you do not provide it, an error will be thrown.
var name = root.GetProperty("name").GetString();
return new Response(200, $"Hello, {name}");
}
}
Example of input data (the POST method):
{
"name": "Anonymous"
}
The log will contain the following:
POST, { "name": "Anonymous" }
Response returned:
Hello, Anonymous