How to update entity through navigation properties in entity framework?

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Hi,
I have TableA(ID,Name and TableB_ID) and TableB(TableB_ID,Description), which have a 1 to many relationship.
After creating a context, I want to update a record in TableA, changing its TableB_ID value.
The thing is: I don't want to update the value of tableB_ID directly. I want to change that record by specifying a different "Description" value from TableB.

Do I have to write this or does entity framework do this for me?

THanks

What I have tried:

Changing the value of "Description" by using the navigation properties of TableA is not working.

Posted 20-Oct-16 5:10am

RuiBarreiros

Updated 21-Oct-16 11:51am

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Ruard · Accepted Answer · 2016-10-21T11:51:00

I assume that description is unique. So you'll have to search for a matching description yourself. It is something like this:

C#

var descr = "something";
var tabB = context.TableB.FirstOrDefault(f => f.Description == descr );

if (tabB == null)
{
    // Assume TableB_ID is autonumber / identity in database.
    var newTabB = new TableB() { Description = descr };
    TableA.TableB = newTabB ;
    // Not sure if this line is required.
    context.TableB.Add(newTabB);
}
else
    TableA.TableB = tabB;

context.SaveChanges();