Data Annotations

You can add data annotations using the column.Attributes list within UpdateColumn function. This can include custom attributes too.

Example:

Settings.UpdateColumn = delegate(Column column, Table table, List<EnumDefinition> enumDefinitions)
{
    column.Attributes.Add($"[Display(Name = \"{column.DisplayName}\")]");

    if (column.IsPrimaryKey)
        column.Attributes.Add("[Key]");

    if (column.IsPrimaryKey && table.NameHumanCase.Equals("SomeTable", StringComparison.InvariantCultureIgnoreCase))
        column.Attributes.Add("[SomeCustomAttribute]");
}

Adding in attributes will require extra namespaces. These can be added to your Settings.AdditionalNamespaces array in your <database>.tt file.