CODEWITHSUNDEEP
c#linq
Mike Fielden
Mike Fielden

Reputation: 10153

In Linq, check child relationships?

Is there any way in Linq to check to see if a record of a parent exists in its children?

I have a table that has a foreign key relationship with 12 other tables. All I want to do is see if any records in those child tables depend on the parent, so I can delete it without causing errors with FK constraints.

Thanks guys.

I ended up just making an extension class that checked each one... Time consuming but got the job done... I would still like opinions if possible

Upvotes: 1

Views: 725

Answers (2)

gfrizzle
gfrizzle

Reputation: 12609

You could brute-force it and wrap the delete in a try-catch. As long as all the deletes are part of the same context, if one child can't be deleted due to a FK relationship, it will roll back all the deletes in that block.

Upvotes: 1

matt_dev
matt_dev

Reputation: 5236

This may be kinda cludgy, and you would have to loop through your child tables and union them all, but here's a start...

        ParentChildrenDataContext context = new ParentChildrenDataContext();

        var child1Ids = from c in context.ChildType1s
                        select c.ParentId;

        var child2Ids = from c in context.ChildType2s
                        select c.ParentId;


        var allChildren = child1Ids.Union(child2Ids);

        var myParents = from p in context.Parents
                        where allChildren.Contains<int?>(p.ParentId)
                        select p;

        return myParents.Count();

Upvotes: 0

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