I was trying to delete a item from my database with some childrens. But i got the error

A relationship is being added or deleted from an AssociationSet ‘FK_ItemChildren_Item’. With cardinality constraints, a corresponding ‘ItemChildren’ must also be added or deleted.

I started to google on it and i found this thread in the MSDN forums. The first suggestion where to add cascade delete to the database and then update the model to get the changes. I did that but i still got the same error. The problem where this.

The SSDL part of the edmx file where updated correctly.

<Association Name="FK_ItemChildren_Item">
 <End Role="Item" Type="Model.Store.Item" Multiplicity="1">
  <OnDelete Action="Cascade" />
 </End>
 <End Role="ItemChildren" Type="Model.Store.ItemChildren"
  Multiplicity="*" />
 <ReferentialConstraint>
 ..
 </ReferentialConstraint>
</Association>

But the CSDL part where not updated:

<Association Name="FK_ItemChildren_Item">
 <End Type="Model.Item" Role="Item" Multiplicity="1">
  <OnDelete Action="Cascade"></OnDelete>
 </End>
 <End Type="Model.ItemChildren" Role="ItemChildren"
  Multiplicity="*">
 </End>
</Association>

The line in “<OnDelete Action=”Cascade”></OnDelete>” where not updated for some reason. When i added that in the model it worked. I guess the designer is not 100% even though the released EF.

UPDATE!

Alexander Muylaert sent me this script via the comments.

Thanks for your blog.  I had this issue on a huge model.  Over 180 tables and hundreds of references.  I didn’t feel like checking all this manually.

I open the edmx file as an xmldocument and executed the following code.  It fixes this issue in batch…  The code is not cleaned, but I have already lost a complete day and I can’t afford to waste more time.  I would like to post this, so someone could use this code and post a cleaned version.

private static string MakeKey(string aAssociation, string aRole) {
        return aAssociation + "_/\\_" + aRole;
    }

    public static void FixCascadeDeleteIssues(XmlDocument XDOC, XmlNode SSDLNode, XmlNode CSDLNode, ref bool aChanged) {
        HashSet lst = new HashSet();

        foreach (XmlNode SSDLChild in SSDLNode) {
            if (SSDLChild.Name == "Association") {
                foreach (XmlNode EndChild in SSDLChild) {
                    if (EndChild.Name == "End") {
                        foreach (XmlNode DeleteChild in EndChild) {
                            if (DeleteChild.Name == "OnDelete") {
                                var x = DeleteChild.Attributes.GetNamedItem("Action");
                                if (x.Value == "Cascade") {
                                    lst.Add(MakeKey(SSDLChild.Attributes.GetNamedItem("Name").Value, EndChild.Attributes.GetNamedItem("Role").Value));
                                }
                            }
                        }
                    }
                }
            }
        }

        Dictionary FMaps = new Dictionary();

        foreach (XmlNode CSDLChild in CSDLNode) {
            if (CSDLChild.Name == "EntityContainer") {
                foreach (XmlNode ContainerChild in CSDLChild) {
                    if (ContainerChild.Name == "AssociationSet") {
                        foreach (XmlNode EndChild in ContainerChild) {
                            if (EndChild.Name == "End") {
                                string Association = ContainerChild.Attributes.GetNamedItem("Name").Value;
                                string Role = EndChild.Attributes.GetNamedItem("Role").Value;
                                string EntitySet = EndChild.Attributes.GetNamedItem("EntitySet").Value;

                                FMaps.Add(MakeKey(Association, Role), EntitySet);
                            }
                        }
                    }
                }
            }
        }

        foreach (XmlNode CSDLChild in CSDLNode) {
            if (CSDLChild.Name == "Association") {
                string Association = CSDLChild.Attributes.GetNamedItem("Name").Value;

                if (Association == "FK_DEV_PARENT_DEV_ID") {
                    Console.WriteLine("");
                }

                foreach (XmlNode EndChild in CSDLChild) {
                    if (EndChild.Name == "End") {

                        string Multiplicity = EndChild.Attributes.GetNamedItem("Multiplicity").Value;
                        if (Multiplicity == "*") {
                            continue;
                        }

                        string role = EndChild.Attributes.GetNamedItem("Role").Value;
                        string v;
                        if (FMaps.TryGetValue(MakeKey(Association, role), out v)) role = v;
                        string key = MakeKey(CSDLChild.Attributes.GetNamedItem("Name").Value, role);

                        if (lst.Contains(key)) {
                            bool hasdel = false;
                            foreach (XmlNode DeleteChild in EndChild) {
                                if (DeleteChild.Name == "OnDelete") {
                                    var x = DeleteChild.Attributes.GetNamedItem("Action");
                                    if (x.Value == "Cascade") {
                                        hasdel = true;
                                    }
                                }
                            }
                            if (!hasdel) {
                                XmlNode newSub = XDOC.CreateNode(XmlNodeType.Element, "OnDelete", NamespaceDelete);
                                XmlAttribute xa = XDOC.CreateAttribute("Action", null);
                                xa.Value = "Cascade";
                                newSub.Attributes.Append(xa);
                                EndChild.AppendChild(newSub);
                                aChanged = true;
                            }
                        }
                    }
                }
            }
        }
    }

This code looked fine to me. It’s kind of massive and a lot of joins but it should be used in a admin interface so i did not care that much. But it turned out that it timeout every time in ran it. I had a look at the SQL that was generated and that was not a pretty sight. A massive amount of sub queries and left outer joins.

I posted a question on the new and really really good code community Stackoverflow and got the tip that i should join the tables before group by clue. And that is what i tried to do.

The problem was that i got this error all the time.

from s in db.ForumStatsSet
from t in s.Topic

Error:
An expression of type ‘WhoaAdmin.Models.Topic’ is not allowed in a subsequent from clause in a query expression with source type ‘System.Data.Objects.ObjectQuery<WhoaAdmin.Models.ForumStats>’. Type inference failed in the call to ‘SelectMany’.

I tried to google that error and i got nothing. I realised that maybe you have to do the joins in the correct order and that was it and i ended up with this query.

The SQL i ended up with looks kind of awful but probably the SQL engine do something like this “under the hood” on regular SQL group by to. At least it is kind of fast. The big diffrence in the generated SQL is that it has replaced all “LEFT OUTER JOINS” with “INNER JOINS” and they are of course faster.

Please leave comment.