Linq 查询具有父子关系中的多个对象

Question

I have a schema like this

Package -> Lists -> Users

All 'one to many' down the line...

So I want to run a query where I get all packages that a userID matches in users.

var pck = (from pk in context.Package
             where pk.Lists[here's my problem]

I would assume the navigation properties here would be: pk.Lists. *Users.UserId* == MyUserId pk.Lists. *Users.UserId* == MyUserId , however I'm not seeing the navigation properties at the Lists level.

I haven't gotten to more complex EF queries like this yet. I've looked around the web but haven't found anything to make it click. I turn to you stack. Somebody help me see the light!

EDIT: Thanks again stack, I will do my best to pay it forward, Also, all of these answers enlightened me to the power of ef4!

Answer 1

I assume that a package contains multiple lists, and a list contains multiple users? You could try:

var pck = content.Package
     // Outdented just for Stack Overflow's width
     .Where(pk => pk.Lists.Any(list => list.Any(u => u.UserId == myUserId)));

Or use a cross-join:

var pck = from pk in content.Package
          from list in pk.Lists
          from user in list.Users
          where user.UserId == myUserId
          select ...; // Select whatever you're interested in

Answer 2

try this:

pk.Lists.Any(l => l.Users.Any(u => u.UserId == MyUserId))

Answer 3

context.Packages.Where(p => p.Lists.Any(l => l.Users.Contains(MyUserId)))

or, if your user is something other then just a user id,

context.Packages.Where(p => p.Lists.Any(l => l.Users.Any(u => u.Id == MyUserId)))

Answer 4

var packages =
    context.Package.Where(p =>
        p.Lists.Any(l => 
            l.Users.Any(u => u.UserId == MyUserId
        )
    );

Answer 5

If the links are non-nullable and direction is package has many lists and list has many users, then the query is pretty easy.

var pck = from user in context.Users
          where user.UserId == userId
          select user.List.Package;