Hi Gerry,
From your description, you're using ADO.NET Entity Framework to deal with
some relationed database tables. However, you found that some
NavigationProperties(geneated by the EDM tools in Visual studio) cannot
load records, correct?
I've setup 3 tables per your case and performed some local tests. My table
schema is exactly as what you have:
table1
table2 are pk tables
while table3 contains FK to both table 1 and table2
At first, I also got the problem you encountered. And as you said, there
is
no "Load" method on the table3.table2Item or table3.table1item Navigation
property. However, I found that there is another property called
"[NavigationProperty]Reference". Therefore, for this case, in addition to
"table3.table1item" and "table3.table2item", there also contains the below
2 propeties:
table3.table1itemreference
table3.table2itemreference
And you can call "Load" method on these two properties so as to load the
relationed records. Here is the test code I used which can navigate from
table1 to table3 and to table2.
=================================
static void RunEDM()
{
EDMConsoleApp.testdb testdb1 = new testdb();
foreach (var t1item in testdb1.table1)
{
t1item.table3item.Load();
Console.WriteLine("id:{0}, name:{1}, t3itemcount:{2}",
t1item.t1_id, t1item.t1_name, t1item.table3item.Count);
foreach (var t3item in t1item.table3item)
{
t3item.table2itemReference.Load();
Console.WriteLine("t3_id{0}, t2_id{1}", t3item.t3_id,
t3item.table2item.t2_id);
}
}
}
=======================================
In addition, here are some web articles discussing about EDM and
relations:
#Entity Data Model 101: Part 1
http://blogs.msdn.com/adonet/archive/2007/01/30/entity-data-model-part-1.asp
x
#Entity Data Model Associations: Where's my Foreign Key?
http://www.thedatafarm.com/blog/2007/09/11/EntityDataModelAssociationsWheres
MyForeignKey.aspx
Hope this helps.
Sincerely,
Steven Cheng
Microsoft MSDN Online Support Lead
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--------------------
From: "gerry" <
[email protected]>
Subject: EntityFramework
Date: Wed, 24 Dec 2008 12:31:00 -0500
I have 2 tables associated through a 3rd table :
table1
ID - key
Value
table2
ID - key
Value
table3
ID1 - FK table1
ID2 - FK table2
Seq
Using the data model generated by the designer , how do I access
table2.Value :
using ( DBEntities dbe = new DBEntities() )
{
foreach ( Item1 t1item in dbe.Table1Items )
{
t1item .Table3Items.Load();
Console.WriteLine("{0} {1} {2}" , t1item.ID , t1item.Value ,
t1item.Table3Items.Count );
foreach ( Item3 t3item in i.Table3Items )
{
Console.WriteLine("\t{0} {1} {2} {3}" , t3item.ID1 , t3item.ID2 ,
t3item.Seq );
// *********************************
// t3Item.ID2 has a value and there is an existing item in table2
with that key value
// t3Item.Table2Item is always null & there is no t3Item.???.Load()
to load it.
//
Console.WriteLine("\t{0} {1} {2} {3}" , t3Item.Table2Item.Value );
}
}
}
