Wizz's Coding Solutions » Circular Reference http://rainstorms.me.uk/blog Problems that I come across in day to day coding Thu, 07 Jul 2011 07:50:18 +0000 en hourly 1 http://wordpress.org/?v=3.2.1 Linq to SQL Quirks Part 4: Circular References http://rainstorms.me.uk/blog/2009/07/10/linq-to-sql-quirks-part-4-circular-references/ http://rainstorms.me.uk/blog/2009/07/10/linq-to-sql-quirks-part-4-circular-references/#comments Fri, 10 Jul 2009 07:54:24 +0000 wizzard http://rainstorms.me.uk/blog/?p=239 Yet Another Related Posts Plugin.]]> This entry is part of a series, Linq to SQL Quirks»

In a project that I am working on at the moment, I have a situation where I have a Person table and a Family table.  The Person table has a FamilyID field, which is a foreign key to the Families ID (primary key) field, and the Family table has a DefaultPersonID, which is another foreign key back to Person to store the default contact for a family.

The problem is that if I create a new Person and Family with the Person being the DefaultContact, I get an InvalidOperationException thrown with a message “A cycle was detected in the set of changes”.  The problem is that Linq to SQL doesn’t know what to store first.  The only way that I have come up with to get around this is to do the following…

            If Person.ID = 0 AndAlso Not Person.Family Is Nothing Then

                Dim fam = Person.Family
                Person.Family = Nothing

                DBContext.SubmitChanges()
                Person.Family = fam

            End If

            DBContext.SubmitChanges()

This works by breaking the circular reference, so that there is only a 1 way reference, then submitting to the database, and once submitted, restoring the removed reference and submitting changes again

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