与LINQ一起使用包含到实体时，相关实体未加载

Question

In my schema, I have the following relevant entities:

Basic schema for Element/Folder/User/Role

I'm trying to load a list of the Folders that each User has access to - either directly or by virtue of the User having a Role that has access to the Folder. I've split the requirement into two pieces (direct and indirect) and used a Union to pull the records back in a single collection, with only one call to the database.

I've got the L2E statement below running - as long as a User has a (direct or indirect) record in Access, the Folder entity will be returned in the list (Note: sUserElmKey is the key of the current User).

Dim fldList = (From fld As Folder In ctxClient.Elements.OfType(Of Folder)() _
               Join acs As Access In ctxClient.Accesses
               On acs.ElementKey Equals fld.ElementKey
               Where acs.UserRoleElementKey = sUserElmKey _
               Select fld
              ).Union _
              (From fld As Folder In ctxClient.Elements.OfType(Of Folder)() _
               Join acs As Access In ctxClient.Accesses
               On acs.ElementKey Equals fld.ElementKey
               Join rol As Role In ctxClient.Elements.OfType(Of Role)()
               On rol.ElementKey Equals acs.UserRoleElementKey
               Where (From usr As User In rol.Users
                      Where usr.ElementKey = sUserElmKey).Any _
               Select fld
              )

This worked fine when I just needed to know if any access to each Folder was available to the User. Now I need to define other logic based on which AccessTypeCode the User has for each Folder.

Given that I need to iterate over the resulting entities in the collection in order to load a different collection of objects that represents nodes in the tree UI, I figured I'd just add an Include("Accesses") to each sub-statement above. As I iterated through the resulting collection, I could write the logic to set the needed flags for each of the new node objects (eg if the User has AccessTypeCode "VIEW", then they have read-only access; "OWN" or "NEW" and they have read/write access).

Unfortunately, I haven't been able to find where to add the Include to do this properly - I've put it after the "ctxClient.Elements" as well as after the ".OfType(Of Folder()", but while the code compiles and runs, the debugger shows 0 records for the Accesses collection under each Folder when I'm iterating.

Rewriting this as a lambda expression is an option, but I think I might just find myself in the same place.

Any ideas on how to resolve this?

Answer 1

Looking at you schema I think you can rewrite the query as follows:

(From fld In ctxClient.Elements.OfType(Of Folder)()
 Where fld.Accesses.Any(Function(acs) acs.UserRoleElementKey = sUserElmKey)
 Select fld)
.Union
(From fld In ctxClient.Elements.OfType(Of Folder)()
 Where fld.Accesses.Any(Function(acs) acs.UserRoleElement.Users
                       .Any(Function(usr) usr.ElementKey = sUserElmKey))
Select fld)

This checks whether there is any access, directly or through roles, without having to Include accesses.