How deeply does ASP.NET Core in Action, 3e cover FromForm?

Defines explicit source selection and its body-binding conflict with FromBody, without detailing formatter or binder internals.

FromForm

As explained in ASP.NET Core in Action, 3e

FromForm is an ASP.NET Core parameter-binding attribute that selects form fields in the request body as the source for a parameter or property.

FromForm is an ASP.NET Core parameter-binding attribute that tells model binding to read a parameter or property from form data posted in the request body. section 16.2.3

Use FromForm when you need to override the default binding source:

Apply it to handler parameters or properties in Razor Pages and MVC controllers. section 16.2.3
Do not combine it with FromBody for the same value; both consume the request body and are effectively mutually exclusive. section 16.2.3
Note that FromForm is unavailable in minimal APIs. section 16.2.3

Listing 16.5 Choosing a binding source for model binding

public class PhotosModel: PageModel
{
    public void OnPost(
        [FromHeader] string userId,       #1
        [FromBody] List<Photo> photos)    #2
    {
        /* method implementation */
    }
}

Compare FromForm with FromHeader and FromBody while reviewing binding-source annotations on an OnPost handler. section 16.2.3

How ASP.NET Core in Action, 3e covers it

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Related concepts

model bindinguses · Model binding is the process of locating incoming data, converting it to appropriate types, and assigning it to application objects or handler parameters.
form datauses · Form data is a collection of named values associated with form controls for submission or processing.

This explainer was generated by Manning's knowledge graph from the text of ASP.NET Core in Action, 3e. The section links point to the parts of the book it draws on.