具有简单列表的对象的C＃筛选器列表

Question

Quite new to LINQ here and I am wondering how to achieve this. I have the following codes:

var allOrgs = (from org in this.Context.Organizations select org).ToList();

var childOrgs = (from oc in this.Context.OrganizationChild select oc).ToList();

var parentOrgs = (from op in this.Context.OrganizationParent select op).ToList();

the return values for each variable as follows:

allOrgs = [{id=1}, {id=2}, {id=3}, {id=4}];
childOrgs = [{id=2}];
parentOrgs = [{id=3}];

I want to filter the allOrgs such that only those items that are not in the childOrgs or parentOrgs would be returned, ie

filteredList = [{id=1}, {id=4}];

I have the following LINQ filter (which I need some help with):

var filteredList = allOrgs.Where(a => childOrgs.Any(c => c.id != a.id));

filteredList = filteredList.Where(f => parentOrgs.Any(p => p.id != f.id));

return filteredList.ToList();

For some reason, I still end up getting all the values...

Appreciate any insight. Thanks!

Answer 1

Just merge the two conditions:

filteredList = allOrgs.Where(a => !childOrgs.Any(c => c.id == a.id)
                               && !parentOrgs.Any(c => c.id == a.id) 
                            );

Note that your original query is backwards - it is looking for all orgs where any parent or child org doesn't match.

Answer 2

您可以为此使用Except ：

var filteredList = allOrgs.Except(parentOrgs).Except(childOrgs).ToList();

Answer 3

Adding on to @DStanley Answer ...

You can also do:

var filteredList = allOrgs.Where(a => !childOrgs.Select(r => r.id).Contains(a.id)
                                    && !parentOrgs.Select(r => r.id).Contains(a.id));

Here is a DEMO