The entity type 'XXX' requires a primary key to be defined. If you intended to use a keyless entity type call 'HasNoKey()'

.NET Core使用EF时 报错如下信息：
The entity type 'XXX' requires a primary key to be defined. If you intended to use a keyless entity type call 'HasNoKey()'

源代码为：
Model.DataModelContext _context = new Model.DataModelContext();

_context.业务方法();

改为如下即可：

using(Model.DataModelContext _context = new Model.DataModelContext())

{

_context.业务方法();

}