Dynamic Data - Hiding Columns in selected PageTemplates

This is a return to IAutoFieldGenrators, what we are trying to do is specify what page template to hide columns on.

First the Attribute class:

[AttributeUsage(AttributeTargets.Property)]
public class HideColumnInAttribute : Attribute
{
    public PageTemplate[] PageTemplates { get; private set; }

    public HideColumnInAttribute()
    {
        PageTemplates = new PageTemplate[0];
    }

    public HideColumnInAttribute(params PageTemplate[] lookupTable)
    {
        PageTemplates = lookupTable;
    }

    public static HideColumnInAttribute Default = new HideColumnInAttribute();
}

public enum PageTemplate
{
    Details,
    Edit,
    Insert,
    List,
    ListDetails,
    // add any custom page templates here
}

Listing 1 - HideColumnIn attribute

here you pass an array of pages that the column should be hidden in.

[MetadataType(typeof(OrderMetadata))]
public partial class Order
{
    public class OrderMetadata
    {
        [DisplayName("Order Date")]
        [HideColumnIn
            (
                PageTemplate.Details, 
                PageTemplate.Edit, 
                PageTemplate.Insert
            )]
        public Object OrderDate { get; set; }
    }
}

Listing 2 - sample metadata for Northwind's Orders table

In Listing 2 we are saying that the OrderDate column should NOT be shown on the Details, Edit and Insert pages.

Next we need an IAutoFieldGenerator class for this feature.

public class HideColumnFieldsManager : IAutoFieldGenerator
{
    protected MetaTable _table;
    protected PageTemplate _currentPage;

    public HideColumnFieldsManager(MetaTable table, PageTemplate currentPage)
    {
        _table = table;
        _currentPage = currentPage;
    }

    public ICollection GenerateFields(Control control)
    {
        var oFields = new List<DynamicField>();

        foreach (var column in _table.Columns)
        {
            // carry on the loop at the next column  
            // if scaffold table is set to false or DenyRead
            if (!column.Scaffold ||
                column.IsLongString ||
                column.IsHidden(_currentPage))
                continue;

            var f = new DynamicField();

            f.DataField = column.Name;
            oFields.Add(f);
        }
        return oFields;
    }
}

public static class ExtensionMethods
{
    public static Boolean IsHidden(this MetaColumn column, PageTemplate currentPage)
    {
        var hideIn = column.Attributes.OfType<HideColumnInAttribute>().DefaultIfEmpty(new HideColumnInAttribute()).First() as HideColumnInAttribute;
        return hideIn.PageTemplates.Contains(currentPage);
    }
}

Listing 3 - the IAutoFieldGenerator class

!Important: It should be noted that all that is required if you already have an IAutoFieldGenerator class is to add the column.Hidden(_currentPage) test in the if statement that skips columns and also have the Extension methods class.

This IAutoFieldGenerator class and Extension methods class in Listing 3 simply test to see if the column is NOT to be shown on the current page passed in the constructor.

A bit more of an explanation is required for what is going on in the Extension method IsHidden. I tried using the DefaultIfEmpty with the Default method but could not get it to work so I added the if null statement and set the hideIn to the defalut value if null.

protected void Page_Init(object sender, EventArgs e)
{
    DynamicDataManager1.RegisterControl(DetailsView1);
    table = DetailsDataSource.GetTable();
    DetailsView1.RowsGenerator = new HideColumnFieldsManager(table, PageTemplate.Details);
}

Listing 4 - sample implementation on the Details page

protected void Page_Init(object sender, EventArgs e)
{
    DynamicDataManager1.RegisterControl(GridView1, true /*setSelectionFromUrl*/);
    DynamicDataManager1.RegisterControl(DetailsView1);
    MetaTable table = GridDataSource.GetTable();
    GridView1.ColumnsGenerator = new HideColumnFieldsManager(table, PageTemplate.ListDetails);
    DetailsView1.RowsGenerator = new HideColumnFieldsManager(table, PageTemplate.ListDetails);
}

Listing 5 - sample implementation in the ListDetails page

Now each page needs to have a RowsGenerator or ColumnGenerator added as in Listings 4 & 5.

Download Project

Hope this helps

Steve