problem with linq in Inheritance

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hi,i have 3 class in my dbml file,Person,Student,Teacher and i have a single table in sql with all property from 3 classes and one field[type] for discriminator
so i wanna read all data from table and show in listview with this code:

C#

 foreach (var item in dbcontext.Peapoles)
            {
                ListViewItem lsitem = new ListViewItem();
                lsitem.Tag = item.;
                lsitem.Text = item.id.ToString();
                ....
                listViewcompanies.Items.Add(lsitem);
}

in this code i can't access child class propery!!!
please help me!!!
sorry for my english

Posted 2-Jul-12 23:46pm

akobar

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OriginalGriff · Answer 1 · 2012-07-03T02:02:00

Solution 1

Don't declare it as a var unless you absolutely have to - try declaring as the type that Peapoles returns. If Peapoles is returning the base class because it doesn't know they are derived instances, then cast the item to the inherited version and try that:

C#

MyClass derived = item as MyClass;
if (derived != null)
   {
   ...
   }

You can only use properties of derived classes if the variable you are accessing them via is derived, not base class.

Posted 3-Jul-12 2:02am

OriginalGriff

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akobar 3-Jul-12 9:57am

tnx for reply,can you give me more description?
give me example with person,studend,,,
tnx

OriginalGriff 3-Jul-12 10:48am

Sorry - I can't.
I have no idea what Peapoles does, how it does it, or what it returns. So I would have to guess - which is not a good idea, in computing! :laugh:
Have a look in the debugger, and see what type is returned. The chances are is a a generic IEnumberable of an existing class, which should help you.

akobar 3-Jul-12 11:29am

do you understand my question??