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Dropdown extension methods

When working with databound dropdown lists, you often need to add a default value. With the InsertDefault() extension (and overloads) the pattern for a setter typically will look like this:

public List<Users> AllowedUsers
          ddlUsers.DataSource = value;
          ddlUsers.ValueField = "Id";
          ddlUsers.TextField = "AccountName";
          ddlUsers.InsertDefault("-- none --");

The InsertDefault method will insert a ListItem with an empty value. To retrieve the ID of the selected user simply use the SelectedValueAsIntegerNullable(), which will do all the tryParsing stuff for you.

public int? SelectedUser
       return ddlUsers.SelectedValueAsIntegerNullable();

The are some other variants, e.g. for working with Guid's.

DropDownList ddlItems;

ddlItems.InsertDefault("-- please select a value --");

int value1 = ddlItems.SelectedValueAsInteger();
int? value2 = ddlItems.SelectedValueAsIntegerNullable();

Guid value3 = ddlItems.SelectedValue();
Guid? value4 = ddlItems.SelectedValueAsGuidNullable();

Last edited Oct 11, 2011 at 11:07 AM by drblame, version 2


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