EF 从数据库生成实体designer.cs没有内容

// Default code generation is disabled for model 'c:\users\dewi jones\documents\visual studio 2012\Projects\dewi_test\dewi_test\Dewi_Model.edmx'.
// To enable default code generation, change the value of the 'Code Generation Strategy' designer
// property to an alternate value. This property is available in the Properties Window when the model is
// open in the designer.
EF 从数据库生成实体designer.cs没有内容。只有以上内容，需要打开edmx。然后右键属性。设置“代码生成策略”为“默认值”