ASP.Net Web API custom model binding with x-www-form-urlencoded posted data - nothing seems to work

Question

I am having a lot of trouble getting custom model binding to work when posting x-www-form-urlencoded data. I\'ve tried every way I can think of and nothing seems to

Answer 1

I would recommend you reading the following blog post in which Mike Stall explains in details how model binding works in the Web API:

There are 2 techniques for binding parameters: Model Binding and Formatters. In practice, WebAPI uses model binding to read from the query string and Formatters to read from the body.

Here are the basic rules to determine whether a parameter is read with model binding or a formatter:

1. If the parameter has no attribute on it, then the decision is made purely on the parameter’s .NET type. "Simple types" uses model binding. Complex types uses the formatters. A "simple type" includes: primitives, TimeSpan, DateTime, Guid, Decimal, String, or something with a TypeConverter that converts from strings.
2. You can use a [FromBody] attribute to specify that a parameter should be read from the body.
3. You can use a [ModelBinder] attribute on the parameter or the parameter’s type to specify that a parameter should be model bound. This attribute also lets you configure the model binder. [FromUri] is a derived instance of [ModelBinder] that specifically configures a model binder to only look in the URI.
4. The body can only be read once. So if you have 2 complex types in the signature, at least one of them must have a [ModelBinder] attribute on it.

So if the source of your data is the request body then you can create a custom MediaTypeFormatter rather than a model binder.