How to add a property to a Table Adapter that can be bound to?

Question

I have a database table TravelRequest that contains, amongst other things, the fields SignOffName and SignOffDate. I have a table adapter TravelRequestTable based on this table. I have a DetailsView control which uses this via an ObjectDataSource. Should be all fairly standard stuff.

What I want to do is add a property called SignOffNameDate to the table adapter that combines the two fields and be able to bind to it in the DetailsView control. I want to do it programmatically rather than adding another column in the SQL because dealing with null values is tricky and depends on some other business rules.

This is what I tried:

public partial class TravelRequestDS
{
    public partial class TravelRequestRow
    {
     public string SignOffNameDate
     {
      get { return CombineNameDate(SignOffName, SignOffDate); }
     }
    }
}

This property works fine when I access it programmatically, but when I try bind to it in my aspx page:

<asp:DetailsView ID="DetailsView_TravelRequest" runat="server" AutoGenerateRows="False"
    DataKeyNames="TravelRequestID" DataSourceID="ObjectDataSource_TravelRequest">
     <Fields>
      <asp:BoundField DataField="SignOffNameDate"
       HeaderText="Sign Off" />
      ...

I get an System.Web.HttpException exception, "A field or property with the name 'SignOffNameDate' was not found on the selected data source."

Any ideas how I can do this? Is there an attribute I need to add to the property?

Answer 1

If you don't want to change your table structure, change the default method that loads data into your adapter (usually called Fill), most likely you are doing a Select * From [TravelRequest] or selecting the individual fields, so what you could do is change your TableAdapter query select statement to something like

Select [YourCol1],[YourCol2], SignOffNameDate as Null From [TravelRequest]

Modifying the default query, and selecting SignOffNameDate as null will give you access to set this value

Answer 2

If your objective is to display the combined result in a single non-editable field you can do it like this:

<asp:DetailsView ID="DetailsView_TravelRequest" runat="server" AutoGenerateRows="False"
    DataKeyNames="TravelRequestID" DataSourceID="ObjectDataSource_TravelRequest">
        <Fields>
            <asp:TemplateField HeaderText="Sign Off" SortExpression="SignOffDate">               
                    <ItemTemplate>
                        <asp:Label ID="Label1" runat="server" Text='<%# Bind("SignOffName") %>'></asp:Label>
                        <asp:Label ID="Label2" runat="server" Text='<%# Bind("SignOffDate") %>'></asp:Label>
                    </ItemTemplate>
            </asp:TemplateField>  
            ...