Let's say that your user didn't want to use a textbox to
edit the Title. Instead they want a drop down list to be displayed. You can
accomplish this by creating a Template field within the GridView control. Stop
your project and follow these steps to create a drop down list when editing the
Title in the GridView control.
1.
Drag a second EntityDataSource control onto your web form.
2.
Click the smart tag and click on the Configure Data Source link.
3.
Select AdventureWorksEntities from the Named Connections list and click
the Next button.
4.
Change the EntitySetName to Contacts.
5.
Uncheck the Select All(Entity Value) checkbox and check the box next to
the Title field.
6.
Click the Finish button.
7.
Click the Source View so you can see the markup. You only want this
control to select the distinct list of titles from the table and you want them
to be ordered alphabetically. You should see the following code in the markup
view.
<asp:EntityDataSource ID="EntityDataSource2" runat="server"
ConnectionString="name=AdventureWorksEntities"
DefaultContainerName="AdventureWorksEntities" EnableFlattening="False"
EntitySetName="Contacts" Select="it.[Title]">
</asp:EntityDataSource>
8.
Change the Select attribute to
Select="DISTINCT it.[Title]"
9.
Add the following attribute to order the records alphabetically.
10. The
markup should look as follows:
<asp:EntityDataSource ID="EntityDataSource2" runat="server"
ConnectionString="name=AdventureWorksEntities"
DefaultContainerName="AdventureWorksEntities" EnableFlattening="False"
EntitySetName="Contacts" Select="DISTINCT it.[Title]" OrderBy="it.[Title]">
</asp:EntityDataSource>
11. Click
back to Design view.
12. Click
the smart tag on the GridView control and select Edit Columns… from the pop-up
menu.
13. Click
on the Title field in the Selected Fields list.
14. Click
on the link above the OK button called "Convert this field into a
TemplateField".
15. Now
click the OK button.
16. Click
the smart tag on the GridView control again and select Edit Templates from the
pop-up menu.
17. The
item template displays the controls displayed in the grid view when simply
looking at the grid. In this example the item template for the Title field is
a label control. The value of the title field will be displayed in the lable.
18. Click
on the EditItemTemplate from the list. This will allow you to change the
control from a textbox to a drop down list.
19. Click
on the textbox in the EditItemTemplate and delete it.
20. Drag
a DropDownList control into the EditItemTemplate.
21. Click
the smart tag next to the DropDownList control and select the Choose DataSource
link.
22. Choose
EntityDataSource2 from the Select a Data Source list.
23. Click
the Refresh Schema link. The Title field should be displayed in the drop down
lists on the form. Click the OK button.
24. This
will populate the drop down list with the distinct list of values in the Title
field from the table. Now you have to configure the control to display the
correct selected value based on the record you are editing.
25. Click
the smart tag next to the DropDownList again. Select Edit Data Bindings… from
the pop-up menu.
26. The
DataBinding form will appear. In the Code Expression text box enter the text
"Bind("Title")". This will select the value in the drop
down list based on the value of the title field of the selected record.
27. Click
the OK button.
28. Run
the project again and click on the Edit link of the first record. You should
see the DropDownList and the correct value selected.
