如何在EF LINQ中连接表

Question

当我尝试加入表格时

var query =
    from foo in db.Foos
    from bar in db.Bars
    where foo.ID == bar.FooID
    where foo.ID == 45
    select bar;


query.toArray()

我收到了这样的错误

Unable to create a constant value of type 'Bar'. Only primitive types ('such as Int32, String, and Guid') are supported in this context.

Answer 1

请尝试改为：

var query =
    from foo in db.Foos
    join bar in db.Bars on foo.ID equals bar.FooID
    where foo.ID == 45
    select bar;

无论如何，我建议你在EDM设计师中模拟Foo和Bar之间的关系，这样你就不需要显式连接了：

var query =
    from foo in db.Foos
    where foo.ID == 45
    from bar in foo.Bars
    select bar;