Create a new attribute for Pages property binding

[rynowak]

We want to create a new attribute [BindProperty] which means that the property should be model bound.

We'll have an override via a property bool SupportsGet which enables binding of the properties for GET requests.

Placing the attribute on a class means that it applies to all public properties in the class. This has overriding behavior - the attribute on the property wins. There is no way to un-bind a property if you use the attribute at the class level.

This new attribute should go in the RazorPages namespace. Features like SupportsGet aren't relevant to controllers.

Examples:

public class Index : PageModel
{
    [BindProperty]
    public string CustomerName { get; set; } // This property is only bound for non-GET requests
}


public class Search : PageModel
{
    [BindProperty(SupportsGet = true)]
    public string Query { get; set; } // This property is bound for all requests
}

[BindProperty(SupportsGet = true)]
public class Search : PageModel
{
    public string Query { get; set; } // This property is bound for all requests

    public bool ImFeelingLucky { get; set; } // This property is bound for all requests
}

[rynowak]

Open question here - should we support this attribute on controllers? Should we add support for SupportsGet to the controller binding plumbing?

If we do these things there's no issue with needing to hide this attribute, it can go in the root MVC namespace.

[DamianEdwards]

@danroth27 RE the putting this on Controllers question. I don't have an issue with it, given it seems so explicit, seems like we'd need a good reason not to support it.

[rynowak]

seems like we'd need a good reason not to support it

I agree. One of our goals is not to introduce new pages only primitives.

[rynowak]

For preview 1 we're adding this for Pages only and it will be in the .RazorPages namespace. We'll move it to the general MVC namespace in preview 2 and support it on controllers as well.

[rynowak]

297196b