How can I provide default expression in the { } of a lambda expression, while still allowing it to be added to?

Question

I am using the Kendo UI MVC Grid and I want to encapsulate boilerplate code so I don't have to duplicate the same code on every grid. Configuring the commands on the grid looks like this:

columns.Command(command =>
            {
                command.Custom("Edit").Text("<span class='k-icon k-edit'></span>").Click("editRecord");
                command.Custom("Delete").Text("<span class='k-icon k-i-delete'></span>").Click("deleteItem");
            }).Width(130);

The edit and delete are boilerplate, however there is a potential for extra custom commands depending on the grid. The type of the lambda for command is of Action<GridActionCommandFactory<T>>. How can I abstract the boilerplate to a method or something while still allowing custom commands to be entered? Psuedo-coding it out I figure it would look something like this:

columns.Command(command =>
            {
                //Custom commands here
                SomeConfigClass.DefaultGridCommands(command);
                //Custom commands here
            }).Width(130);

or maybe:

columns.Command(command =>
            {
                //Custom commands here
                command.DefaultCommands();
                //Custom commands here
            }).Width(130);

And this would include the edit and delete commands. But I have no idea how to modify a lambda expression in such a way, how can I achieve this?

What's the type of `command` parameter here `columns.Command(command => `? i.e. `Action>` — Ivan Stoev, Nov 04 '16 at 20:30

score 0 · Accepted Answer · answered Nov 04 '16 at 20:41

Well I did some more digging and it ended up not being that hard. Not sure if it's the most elegant solution but I did it like this:

public static Action<GridActionCommandFactory<T>> GetDefaultGridCommands<T>(Action<GridActionCommandFactory<T>> customCommandsBeforeDefault = null, Action<GridActionCommandFactory<T>> customCommandsAfterDefault = null) where T : class
    {
        Action<GridActionCommandFactory<T>> defaultCommands = x =>
        {
            x.Custom("Edit").Text("<span class='k-icon k-edit'></span>").Click("editRecord");
            x.Custom("Delete").Text("<span class='k-icon k-i-delete'></span>").Click("deleteItem");
        };

        List<Action<GridActionCommandFactory<T>>> actions = new List<Action<GridActionCommandFactory<T>>>();

        if(customCommandsBeforeDefault != null)
            actions.Add(customCommandsBeforeDefault);
        actions.Add(defaultCommands);
        if(customCommandsAfterDefault != null)
            actions.Add(customCommandsAfterDefault);

        Action<GridActionCommandFactory<T>> combinedAction = (Action<GridActionCommandFactory<T>>) Delegate.Combine(actions.ToArray());

        return combinedAction;
    }

Then calling it in the grid:

columns.Command(KendoUiGridConfig.GetDefaultGridCommands<MyViewModel>()).Width(130);

The Delegate.Combine method was what I was looking for.

How can I provide default expression in the { } of a lambda expression, while still allowing it to be added to?

1 Answers1