How to create a nested GridView to edit EF Code First relation?

I've got a classic Parent-Child relation that I would like to CRUD by using asp:GridView controls. To CRUD the parent is easy, but the challenge is to nest a asp:GridView within a asp:GridView that is able to work on the child relation.

To make the problem easier, I've constructed an example. Consider the following EF-code:

public class Context : DbContext
{         
    public DbSet<Animal> Animals { get; set; }
    public DbSet<Tag> Tags { get; set; }
}

public class Animal
{
    public int AnimalID { get; set; }
    public string Name { get; set; }
    public virtual IEnumerable<Tag> Tags { get; set; }
}

public class Tag
{
    public int TagID { get; set; }
    public string Name { get; set; }
}

I'm using an asp:Gridview to view / edit the Animal objectes:

<asp:GridView runat="server" DataSourceID="animalDataSource" DataKeyNames="AnimalID" AutoGenerateColumns="false">   
    <Columns>
        <asp:BoundField DataField="Description" HeaderText="Description" />
        <asp:CommandField ShowCancelButton="true" ShowEditButton="true" ShowDeleteButton="true" />
    </Columns>
</asp:GridView>

The DataSource is bound with code behind:

protected void DataSource_ContextCreating(object sender, EntityDataSourceContextCreatingEventArgs e) 
{    
        var context = new Context();
        e.Context = ((IObjectContextAdapter)context).ObjectContext; } 
}

I would like to include a nested asp:Gridview as one of the columns to add / remove / edit Tag objects beloning to that Animal. How could I achieve th开发者_StackOverflowis?

The BoundField displays the value of specified DataSource field as text. By using bound field we can bind the data directly by using header text and datafield without using any controls. . The TemplateField allows for a mix of HTML markup, Web controls, and data-binding syntax. We can define our own asp.net controls in template field. so basically you convert a bound field to a template column Template columns also come with a edit template tag which offers you more than the standard editing of that gridview row is desired... e.g when in edit mode put a drop down list in this row for me to select from - possibilities are endless so

• change to template field go to edit

• template add grid control to field

• add Edit/delete link button to it

• go on the property of nested grid under edit template
• find update, row databounfd event etc

• i think this will help

  Dim grd1 As GridViewRow

          Dim gv As GridView
          Dim l1, l2 As Label
          Dim strsql As String
          For Each grd1 In GridView1.Rows
              'find controls of parent gridrow
              l1 = grd1.FindControl("l00")
              l2 = grd1.FindControl("l1")
              gv = grd1.FindControl("gv1")
              strsql = "select file_name from product_file where pname='" & l1.Text & "' and categry='" & l2.Text & "'"
            Dim dt1 As New DataTable()
              Dim da1 As New SqlDataAdapter(strsql, con)
              da1.Fill(dt1)
              gv.DataSource = dt1
              gv.DataBind()
          Next
  

do something like this when you fill your parent grid