Validating an ASP.NET user control from its parent page

Question

I have an asp.net page with a button. This button generates and inserts a user control into the page, so many controls could exist on one page. I need to validate that a certain dynamically generated control inside the generated control exists.

So..Page has 0 to N Control1’s. Each Control 1 can have 0 to N Control2’s. When SaveButton is clicked on Page, I need to make sure there are at least 1 Control2’s inside every Control1.

I’m currently between two options:

• Dynamically insert CustomValidators for each control that is generated, each of which would validate one Control1.

• Do the validation manually (with jQuery), calling a validation function from SaveButton.OnClientClick.

Both are sloppy in their own way – which is why I’m sharing this with you all. Am I missing the easy solution?

Thanks in advance.. (btw – anything up to and including .NET 3.5 SP1 is fair game)

Answer 1

One method you could try is creating and maintaining a simple xml structure that represents your custom control hierarchy. Insert or delete from this structure any time you create or destroy a custom user control. Upon save, validate that the control hierarchy represented in the xml structure is correct. You could save the xml in the Session object to persist it across postbacks.

Answer 2

If you are adding user controls on the fly, you could make each control implement the same interface with a Validate function. That way you can load the controls into a placeholder in each parent control on the page. When the page is submitted, simply loop through the controls in the placeholder, cast them to the interface class and then call the validate function. I doesn't use custom validators, but you can build up a list of validation errors using the object returned from the validate function, you can render this collection of validation errors whichever way you like.

Answer 3

Hmm i like the Interface idea suggested by digiguru but i would use the interface on the container Control1 instead of the sub controls as it seems like the more logical place for the code to live. Heres my take on it:

public interface IValidatableControl
{
    bool IsValidControl();    
}

then implement this on your Control1

public class Control1 : IValidatableControl
{
... Other methods
    public bool IsValidControl()
    {

        foreach(object c in this.Controls)
        {
            if(c.GetType() == "Control2")
                return true;
        }
        return false;
    }

}

There are probably better ways to write this but it should give you enough of an idea to get started.

Answer 4

I think you could do it by assigning a public property in Control1 that references the existence of Control2's ID, and then decorate Control1's class with ValidationProperty. I'm thinking something along these lines:

[ValidationProperty("Control2Ref")]
public partial class Control1 : UserControl
{
    public string Control2Ref
    {
     get { return FindControl("Control2"); }
    }
    // rest of control 1 class
}

And then you should be able to point a RequiredFieldValidator at an instance of Control1.