I have entities Group
and User
.
the Group
entity has Users
property which is a list of Users.
User has a property named IsEnabled
.
I want to write a linq query that returns a list of Group
s, which only consists of User
s whose IsEnabled
is true.
so for example, for data like below
AllGroups
Group A
User 1 (IsEnabled = true)
User 2 (IsEnabled = true)
User 3 (IsEnabled = false)
Group B
User 4 (IsEnabled = true)
User 5 (IsEnabled = false)
User 6 (IsEnabled = false)
I want to get
FilteredGroups
Group A
User 1 (IsEnabled = true)
User 2 (IsEnabled = true)
Group B
User 4 (IsEnabled = true)
I tried the following query, but Visual Studio tells me that
[Property or indexer 'Users' cannot be assigned to -- it is read only]
FilteredGroups = AllGroups.Select(g => new Group()
{
ID = g.ID,
Name = g.Name,
...
Users = g.Users.Where(u => u.IsInactive == false)
});
thank you for your help!
There is no "nice" way of doing this, but you could try this - project both, Group
and filtered Users
onto an anonymous object, and then Select
just the Groups
:
var resultObjectList = AllGroups.
Select(g => new
{
GroupItem = g,
UserItems = g.Users.Where(u => !u.IsInactive)
}).ToList();
FilteredGroups = resultObjectList.Select(i => i.GroupItem).ToList();
This isn't a documented feature and has to do with the way EF constructs SQL queries - in this case it should filter out the child collection, so your FilteredGroups
list will only contain active users.
If this works, you can try merging the code:
FilteredGroups = AllGroups.
Select(g => new
{
GroupItem = g,
UserItems = g.Users.Where(u => !u.IsInactive)
}).
Select(r => r.GroupItem).
ToList();
(This is untested and the outcome depends on how EF will process the second Select
, so it would be nice if you let us know which method works after you've tried it).