Dynamic data: how to filter a drop-down list for a foreign key on an edit page

Question

Using Linq-to-SQL and dynamic data.

On the dynamic data editing screen, the possible values ​​for the foreign key are listed in the drop-down list.

I need to filter out the values ​​listed in this dropdown, preferably by adding a where clause in the linq-to-sql query.

Any ideas?

Answer 1

Well, I found a place to configure this, although I still haven't found a way to override or extend the linq request to load data:

In the \ DynamicData \ FieldTemplates \ ForeignKey_Edit.ascx.cs file (in accordance with the default position), the following call is made in the Page_Load method:

PopulateListControl(DropDownList1); 

This can be completely replaced by your own code. In my case, I first checked if the current table implements the user interface that I defined. If so, use this to get the data to bind the drop down list to, otherwise pass control to the PopulationListControl.

Using a Reflector, it seems that PopulateListControl ultimately uses MetaTable.GetQuery () to get the default query for the table. It would be great to expand this, but instead, let's move on to other things!

Answer 2

I think you have already solved your problem, but I would like to register my solution, just in case, this could help someone!

I followed the path you started by editing ForeignKey_Edit.ascx.cs. After the line PopulateListControl (DropDownList1), I call the RemoveResultsFromOtherUsers () method.

Here is a way:

  private void RemoveResultsFromOtherUsers() { using (var db = new FinWeb3.DynamicData.FinWebDBDataContext()) { var data = db.GetTable(this.Column.Provider.ColumnType); var removableItems = new List<ListItem>(); foreach (var item in data) { var dbItem = item as IDbEntity; if (dbItem.UserName != this.Context.User.Identity.Name) { removableItems.Add( DropDownList1.Items.FindByValue(dbItem.Id.ToString())); } } foreach (var item in removableItems) { DropDownList1.Items.Remove(item); } } } 

IDbEntity is an interface that implements all my linq classes for sql. This interface has the properties Id and UserName. Here, I intend to delete results that are not registered by the current authenticated user.

Thanks for your question and solution!

Answer 3

I would create a custom field template that is a web-based user control and references it in metadata using UIHintAttribute. Note: you will need to create a standard version (usually a hyperlink) and a _Edit version (usually a drop-down list).