Field Templates - ASP.NET Dynamic Data - page 106

Control Mode
Control mode defines the context where the field template will be used. It can be one of
the members of the ASP.NET DataBoundControlMode enumeration:
. ReadOnly templates are used by the Details.aspx page template or custom pages to
display field values in Read-only mode.
. Edit templates are used by the Edit.aspx page template or custom pages to change
field values of an existing row.
. Insert are used by the Insert.aspx page template or custom pages to collect field
values for a new row.
When looking for a ReadOnly field template for the ShippedDate column of the Order
table, which has DateTime data type and no additional metadata attributes in the sample
data model, Dynamic Data finds the DateTime.ascx template. Edit mode is considered
more specific because it requires the field template to not only display the current field
value, but also allow changing it. Therefore, when looking for an Edit field template for
the ShippedDate column, Dynamic Data chooses the template called DateTime_Edit.ascx
if it exists. Note that Dynamic Data uses the “_Edit” suffix for Edit templates and no
suffix for the ReadOnly templates. The Insert mode is even more specific because it might
require special logic to deal with rows that have not been submitted to the database, and
Dynamic Data chooses the template called DateTime_Insert.ascx if it exists.
Mode Fallback
If there is no matching field template for a particular control mode, Dynamic Data uses
fallback logic to find another template for a more generic mode. In this ongoing example,
when looking for an Insert template for the ShippedDate column, Dynamic Data will first
try to find the template called DateTime_Insert.ascx . Because there is no field template
with this name, it falls back from the Insert to the Edit mode and ends up using the
template called DateTime_Edit.ascx , assuming it can handle both Edit and Insert modes.
Similarly, if an Edit mode template cannot be found, Dynamic Data falls back to Read-
only mode.
However, before Dynamic Data falls back to the next mode , it performs the type fallback.
Consider UnitsInStock, an Int16 column from the Products table. When looking for an
Edit template for this field, it tries using System.Int16_Edit.ascx and Int16_Edit.ascx
templates first, but because they do not exist, it falls back to type Int32 and checks for
System.Int32_Edit.ascx and Int32_Edit.ascx and eventually finds Integer_Edit.ascx .
If Dynamic Data performed the mode fallback first, it would skip this template and try to
look for a ReadOnly template called System.Int16.ascx instead.