How to define attributes to Custom GridView?

Question

User829868397 posted

Hi,

I have a custom GridView and have custom attributes.

e.g.

  C#:

    public class EpwGridView : GridView
    {
....
        public string EpwDataSessionId { get; set; }
        public string EpwDataSourceType { get; set; }

....
}

 ASPX:
<epw:EpwGridView ID="GridView1"  SkinID="epwGridView" runat="server" DataKeyNames="EpwRowId" EpwDataSessionId="statsData" EpwDataSourceType="DataView">
...
</<epw:EpwGridView></epw:EpwGridView>>
  

But I need to provide more control over these attributes. e.g.

EpwDataSourceType has to be either 'DataView', 'DataTable', 'ObjectDataSource'.

Both , EpwDataSourceType and EpwDataSessionId are required attributes. Meaning the ASPX page should throw an error if these are not defined.

How can I do that?

 

Any help or reference links are greatly appreciated.

 

Thanks

hpdotnet

 

 

Answer 1

User-1995538749 posted

First off, I'd change your EpwDataSourceType to an Enum. Secondly, within the getter of your properties, you can throw a NullReferenceException if the underlying member is null. This however will most likely exclude you from using auto-implemented properties.

Answer 2

User829868397 posted

Thanks ecbruck for the quick reply.

I tried this:

        public enum EpwDataSourceType
        {
            ObjectDataSource,
            DataView,
            DataTable
        }
        

But how do I see it as a property in my custom EpwGridView aspx tag. I want it similar to the runat="server" tag where the developer can only put in the "server" option. The only difference being, this one has 3 options.

Thanks

hpdotnet 

 

Answer 3

User-1995538749 posted

It will need to be defined outside of your custom GridView class.

Answer 4

User829868397 posted

Required property -

If I throw an exception in the getter, it means I am not forcing the developer to set a value for that property. It will throw an exception only when the code tries to use that property.

Is there no other way to make a property of custom Control required?

 

Property value options - 

What do you mean by 'outside of the custom GridView class'? The property is defined in the Custom class. You mean the 'value options' should be defined in a separate class?

Thanks

hpdotnet 

 

 

Answer 5

User-1995538749 posted

I've never used it, but you can look at the RequiredAttribute class:

http://msdn.microsoft.com/en-us/library/microsoft.build.framework.requiredattribute.aspx

Your Enum should be defined as Public outside of your CustomControl class so that it can be accessed outside of the class.

Answer 6

User829868397 posted

 The RequiredAttribute does not work. For not, I am explicitly checking the value and throwing an exception if null.

Thanks for the input on Enum. I now have an enumerator that is used by the control property. This enforces the developer to pick from the enum list as the property value.

Here's one more useful link: 

http://msdn.microsoft.com/en-us/library/aa720440(VS.71).aspx 

 
Here's my code:

 

namespace EPWWEB.WebControls
{
...
    // The DataSourceType enumeration.
    public enum DataSourceType
    {
        DataView,
        DataTable,
        ObjectDataSource,
    }
..
    public class EpwGridView : GridView
    {
...
        private DataSourceType epwDataSourceType;
        [
        DefaultValue(DataSourceType.DataView),
        Description("Defines the underlying data source"),
        ]
        public DataSourceType EpwDataSourceType
        {
            get
            {
                    return epwDataSourceType;
            }
            set
            {
                epwDataSourceType = value;
            }
        }

  }