MVC WebGrid - How to call a method on WebGridRow item / model?

Question

When using WebGrids, I find that I can access properties on the model bound to the WebGrid, but I can't access methods on the Model itself.

As an example, this works:

// Accessing a property of item works
reportGrid.Column("", header: "First Name", format: item => item.firstName )

But this does not work: (I am showing a trivial example, but for my case I must call a method on the User object itself.)

// Accessing a method on item does not work 
reportGrid.Column("", header: "First Name Backwards", format: item => item.firstNameBackwards() )

=> error: 'System.Web.Helpers.WebGridRow' does not contain a definition for 'getFullName'

This seems related to the following:

Why can't I use my extension method in a delegate in the Razor WebGrid http://www.mikesdotnetting.com/Article/171/Why-You-Can%27t-Use-Extension-Methods-With-A-WebGrid

I don't see a way to apply these solutions to my problem. As Mike Brind states:

The argument that the WebGridColumn's Format parameter takes is a delegate: Func. What this means is that you have to pass in a dynamic type, and then something is done to it before it is returned as an object.

...

When you try to use an extension method, the Compiler will check the type you are trying to use it on to see if such a method exists. If it doesn't. it will check any base classes that the type derives from to see if they contain a formal method with the right name.

It seems like my method should be found, but perhaps not because the model bound to the WebGrid is actually a paging model that contains IList<T> LineItems which hold my User references.

Is there any way to cast or get a reference to the User object itself so I can call methods defined on it in addition to accessing its properties?

score 1 · Answer 1 · answered Apr 04 '14 at 19:40

I found a way around this problem, but I'm still hopeful there is a better way. I would appreciate any feedback on this or alternate solutions.

In exploring this issue and examining some of my other WebGrid code, I found that I am able to access 2nd order methods defined against objects that can be accessed through properties on the model object bound to the WebGrid.

Example (simplified):

reportGrid.Column("", header: "First Name Backwards", 
  format: item => item.BestFriend.firstNameBackwards() )
=> Works!

Taking this a step further, I traced the bi-directional relationship back to the original object so I could call its methods:

// Assume all best-friend relationships are reciprocal 
reportGrid.Column("", header: "First Name Backwards", 
  format: item => item.BestFriend.BestFriend.firstNameBackwards() )

=> Works!

With this in mind, I modified my User model to contain a reference to itself:

    public User() {
        this._self = this; // Initialize User object with a reference to itself
    }

    [NotMapped]
    public User _self { get; set; }

Solution - now I can call methods defined against the User model using the _self property.

reportGrid.Column("", header: "", 
  format: item => Helper.userTML(item._self.firstNameBackwards() ) )

=> Works!

score 0 · Answer 2 · answered Jan 26 '16 at 20:00

In exploring this issue and examining some of my other WebGrid code, I found that I am able to access 2nd order methods defined against objects that can be accessed through properties on the model object bound to the WebGrid.

I had the same issue and per this comment, I had figured out it was because I didn't expose the data members of the model. Set your firstName definition to public and that will fix it.

score 0 · Answer 3 · answered Apr 08 '16 at 13:15

I found the best way that worked for me was using a getter in the model class.

In your model class (User?):

public string firstNameBackwards
{
    get 
    { 
        var firstNameBackwards = firstName;
        // Do something here
        return firstNameBackwards; 
    }
}

In your webgrid:

reportGrid.Column("", header: "First Name Backwards", format: item => item.firstNameBackwards )

MVC WebGrid - How to call a method on WebGridRow item / model?

3 Answers3