What is model binding in ASP.NET Core WebAPI?

Model binding in ASP.NET Core WebAPI is a feature that allows incoming HTTP requests to be automatically mapped to parameters of controller action methods. When a client sends an HTTP request with data, such as query string parameters, form data, JSON payload, or route values, ASP.NET Core WebAPI can bind this data directly to parameters of controller action methods without explicit code to parse and extract the data.

For example, if you have a POST request with a JSON payload like this:

{
  "id": 1,
  "name": "John Doe",
  "email": "john@example.com"
}

And you have a corresponding controller action method like this:

[HttpPost]
public IActionResult Create([FromBody] User user)
{
    // Code to process the user data
}

ASP.NET Core WebAPI will automatically deserialize the JSON payload into a User object and pass it as an argument to the Create method.

Model binding supports various sources for data including query strings, form data, route values, and JSON payloads. It also supports complex types, collections, and nested objects, making it easy to work with structured data.

Model binding in ASP.NET Core WebAPI helps to simplify controller code by eliminating the need for manual parsing of incoming request data, leading to cleaner and more maintainable code. It also helps in handling validation and conversion of data types automatically.