Poco Parent-Child relation lost Client-side - entity-framework-4

Question

I have this scenario:
STRUCTURE :
Entity A
ChildEntity B
Assume this is data in my database
A1
(childs)
B1
B2
B3
A2
(childs)
B4
B5
B6
Using linq to SQL. I want a list of B items
with a reference to parents (A items)
Server side it's all right before my web service send back data to client
I got a structure like this:
B1
A1
(childs)
B1
B2
B3
B2
A1 (parent)
(childs)
B1
B2
B3
...
...
If I try to navigate the Graph all items seems to be in the right place.
Client side, after server serialization and client deserialization I have this situation:
B1
A1 (parent)
(childs)
B1
B2
B3
B2
NULL
B3
NULL
B4
A2 (parent)
(childs)
B4
B5
B6
B5
NULL
B6
NULL
ONLY one of the childs of A items keeps the reference to the parent. I tried to look at XML generated both client and server side but couldn't find the problem.
Can anyone try to help me understand why this happens?
Or have a suggestion?
NOTE :
If I try to compress the list server side, as byte[], and decompress it back client side, casting the compressed object to List<B>, all items maintain the correct relation also client side, everything is okay. So I imagine it's a problem in Serialization/Deserialization
I'm using:
standard serialization (DataContractSerializer)
standard microsoft POCO template
EF4.

Answer 1

I found where the problem was :
The XMLSerializer when serializing properties puts them in the XML apparently in random order (maybe it follows some order it gets from Datamodel edmx, i've not investigated about it)
So i got this scenario in XML generated by the XMLSerializer :
<b:CHILD_Entity **z:Id="i1"** xmlns:z="http://schemas.microsoft.com/2003/10/Serialization/">
<b:CHILD_ID>008acd9a-2074-46b0-b73b-90b8c9123f6f</b:CHILD_ID>
<b:ReasonInfo>HRC->PLC 11</b:ReasonInfo>
<b:StartTime>2011-11-29T09:22:36.553</b:StartTime>
<b:EndTime>2011-11-29T10:31:58.507</b:EndTime>
<b:Quantity>0</b:Quantity>
<b:PARENT_Entity z:Id="i2">
<b:Description i:nil="true"></b:Description>
<b:UtilizationType>COMMITTED</b:UtilizationType>
<b:Reason>SETUP</b:Reason>
<b:ReasonInfo></b:ReasonInfo>
<b:CHILD_Entities>
<b:**CHILD_Entity** **z:Ref="i1"**></b:CHILD_Entity>
<b:**CHILD_Entity** **z:Id="i3"** xmlns:z="http://schemas.microsoft.com/2003/10/Serialization/">
<b:CHILD_ID>008acd9a-2074-46b0-b73b-90b8c9123f6f</b:CHILD_ID>
<b:ReasonInfo>HRC->PLC 11</b:ReasonInfo>
<b:StartTime>2011-11-29T09:22:36.553</b:StartTime>
**<b:ProductionCapabilityUtilization z:Ref="i2"></b:ProductionCapabilityUtilization>**
***<b:PARENT_ID>32864280-fe68-4b21-8375-b57ae8bbd7e6</b:PARENT_ID>***
..........
</b:CHILD_Entity>
..................
</b:CHILD_Entities>
**<b:PARENT_ID>32864280-fe68-4b21-8375-b57ae8bbd7e6</b:PARENT_ID>**
</b:PARENT_Entity>
***<b:PARENT_ID>32864280-fe68-4b21-8375-b57ae8bbd7e6</b:PARENT_ID>***
<b:PROP1>MLM</b:PROP1>
<b:PROP2>MLM1</b:PROP2>
<b:Reason>RUN</b:Reason>
</b:CHILD_Entity>
<b:**CHILD_Entity** **z:Ref="i3"** xmlns:z="http://schemas.microsoft.com/2003/10/Serialization/"></b:CHILD_Entity>
the problem is that could happen that sometimes FIXUP generated code try to set PARENTID on CHILD_Entity before PARENT_Entity.PARENT_ID is set and after CHILD_Entity.PARENT_Entity SETTER was fired.
so we got a strange scenario where CHILD_Entity.PARENT has a value but CHILD_Entity.Parent.PARENT_ID = NULL because the DESERIALIZER has still not processed that property from the XML
To solve this kind of problems i had to modify POCO Template this way :
Set a counter variable int propertyPosCounter = 1;
Specify ORDER when setting DataMemberAttribute
[DataMemberAttribute(Order = <#=propertyPosCounter.ToString()#>)]
Increment the counter after that propertyPosCounter +=1;
REPEAT This process for each Primitive Properties - Complex Properties - Navigation Properties
in order we got always the right order in generated XML to Deserialize Client Size using POCO and it's Fixup concept
After this adjustemant to the POCO.tt template i solve those kind of conflicts and got no problems
Serializing -> Deserializing my data structures passed from my WCF service to my client application
the result in the XML serialized is :
<b:CHILD_Entity z:Id="i1" xmlns:z="http://schemas.microsoft.com/2003/10/Serialization/">
<b:CHILD_ID>008acd9a-2074-46b0-b73b-90b8c9123f6f</b:CHILD_ID>
<b:PARENT_ID>32864280-fe68-4b21-8375-b57ae8bbd7e6</b:PARENT_ID>
<b:PROP1>MLM</b:PROP1>
<b:PROP2>MLM1</b:PROP2>
<b:Reason>RUN</b:Reason>
<b:ReasonInfo>HRC->PLC 11</b:ReasonInfo>
<b:StartTime>2011-11-29T09:22:36.553</b:StartTime>
<b:EndTime>2011-11-29T10:31:58.507</b:EndTime>
<b:Quantity>0</b:Quantity>
<b:PARENT_Entity z:Id="i2">
<b:PARENT_ID>32864280-fe68-4b21-8375-b57ae8bbd7e6</b:PARENT_ID>
<b:Description i:nil="true"></b:Description>
<b:UtilizationType>COMMITTED</b:UtilizationType>
<b:Reason>SETUP</b:Reason>
<b:ReasonInfo></b:ReasonInfo>
<b:CHILD_Entity>
<b:CHILD_Entity z:Ref="i1"></b:CHILD_Entity>
<b:**CHILD_Entity** **z:Id="i3"** xmlns:z="http://schemas.microsoft.com/2003/10/Serialization/">
<b:CHILD_ID>008acd9a-2074-46b0-b73b-90b8c9123f6f</b:CHILD_ID>
***<b:PARENT_ID>32864280-fe68-4b21-8375-b57ae8bbd7e6</b:PARENT_ID>***
<b:ReasonInfo>HRC->PLC 11</b:ReasonInfo>
<b:StartTime>2011-11-29T09:22:36.553</b:StartTime>
..........
**<b:ProductionCapabilityUtilization z:Ref="i2"></b:ProductionCapabilityUtilization>**
</b:CHILD_Entity>
</b:CHILD_Entity>
</b:PARENT_Entity>
</b:CHILD_Entity>
I tried to be as clear as possible but the scenario is not trivial, so if anyone needs clarification do not hesitate to ask for it, i will try to answer as soon as i can.
Hope this post could help someone else :)
Regards,
Luigi Martinez Bianchi