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Pål asked on 16 Jan 2010, 09:23 PM

Hi!

During serialization of an ObjectContainer I get the following Exception:

Unable to cast object of type 'Telerik.OpenAccess.RT.StructFieldMarker' to type 'Telerik.OpenAccess.SPI.dataobjects.PersistenceCapable'.

I believe this has to do with classe having persistent structs attaced to them.

Here is the Class that won't serialize

    
            [Persistent, Serializable]  
        
            public class Order : ISerializable {  
        
                /// <summary> 
        
                /// The <see cref="Quantity"/> of this order  
        
                /// </summary> 
        
                private Quantity m_Quantity;  
        
            (...)  
        
            }

Here is the Quantity Struct:

    
            [Persistent, Serializable]  
        
            public struct Quantity : ISerializable {  
        
                /// <summary> 
        
                /// The decimal value of this Quantity  
        
                /// </summary> 
        
                private decimal m_Value;  
        
                /// <summary> 
        
                /// The Unit for this Quantity  
        
                /// </summary> 
        
                private Unit m_Unit;  
        
            (...)  
        
            }

And here is the mapping:

    
            <class name="Order">  
        
              <extension key="db-inheritance" value="vertical" /> 
        
              <extension key="db-table-name" value="Order" /> 
        
              <field name="m_Quantity">  
        
                <extension key="field" value="m_Unit">  
        
                  <extension key="db-column">  
        
                    <extension key="db-column-name" value="Quantity.UnitID" /> 
        
                  </extension> 
        
                </extension> 
        
                <extension key="field" value="m_Value">  
        
                  <extension key="db-column">  
        
                    <extension key="db-column-name" value="Quantity.Value" /> 
        
                  </extension> 
        
                  <extension key="null-value" value="exception" /> 
        
                </extension> 
        
              </field> 
        
            (...)  
        
            </class>

Please help.

Thanks

Pål

5 Answers, 1 is accepted

answered on 17 Jan 2010, 09:32 PM

Hi again.

Update:

I have located the source of the error (i think) and it occurs on deserialization of "ObjectContainer" when it contains persistent structs with persistent references in them (se my "Quantity" struct above, which contains a reference to a persistent "Unit").

Anyway, the exception is initiated from "Telerik.OpenAccess.RT.DisconnectedStateManager", method: "CheckSerializationConsistency" (se below). I believe the indexes retrieved in the "numArray" are wrong and so a "StructFieldMarker" is passed to "helper.extractReferences(...)" which will later try to cast it as a "PersitentCapable" object.

Here is where the fatal call is made from (and where the erronus array indexes are retrieved):

    
            internal void CheckSerializationConsistency(ReferenceCollector coll)  
        
                {  
        
                  ReferenceHelper helper = this.referenceHelper();  
        
                  int[] numArray = helper.getReferencingFieldNums();  
        
                  for (int i = numArray.Length - 1; i >= 0; i--)  
        
                  {  
        
                    int index = numArray[i];  
        
                    object x = this.data[index];  
        
                    if ((x != null) && (x != invalidFieldContentMarker))  
        
                    {  
        
                      helper.extractReferences(x, index, coll, this);  
        
                    }  
        
                  }  
        
                }

This is the source of the actual Exception. x variable is passed a "StructFieldMarker":

    
                public override void extract(object x, ReferenceCollector coll, StateManager sm)  
        
                {  
        
                  coll.Add((PersistenceCapable) x, base.slot, false, sm);  
        
                }

If the array values are messed up on serialization or deserialization, I don't know, but I think it's one of them.

Hope this helps in locating the bug.

Thanks

Pål