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Persisting primitive arrays

2/1/2007 5:17:58 AM

stunney

1 posts

Persisting primitive arrays
Modified By stunney on 2/1/2007 6:19:42 AM)

Hello, I was hoping that someone might be able to help me on a subject that is probably easily fixed, but I have not yet found a solution.
Suppose the following class

[NDOPersistent]
public class MyClass {
private int m_Value = 0;
private int[] m_Stuff;

public int Value{ get{ return m_Value; } }
public int[] Stuff{ get{ return m_Stuff; } set { m_Stuff = value; } }
}

When I build my solution, and the mapping file is generated, there is no Field node under MyClass to show that m_Stuff will be persisted.
Thoughts?

2/1/2007 8:44:31 AM

Mirko

109 posts

Re: Persisting primitive arrays

Hi Stunney,

thanks for your interest in NDO. There is no way for NDO to know, how it should persist your int array in a relational database. That's the reason, why NDO ignores your array. There are two main options you can choose if you want to persist your array: the first is storing the values in a blob column of your table, the second is to store the values in an own table with a foreign key column that connects to the MyClass table.

To achieve the first scenario you define a persitent byte[] variable. Implement the IPersistenceNotifiable interface and use the OnLoading and OnSaving functions to convert the byte[] to the int[] and vice versa. Make sure to mark your object as dirty, if you change the content of the int[] array:
((IPersistenceCapable)this).NDOMarkDirty();
A similar approach would be to convert your int[] to a persistent string variable.

In the second scenario you need a special class holding the integer, and define a 1:n relation to that class:

[NDOPersistent]
public class Stuff
{
    public Stuff(int val)
    {
        this.value = val;
    }
    int value;
}

[NDOPersistent]
public class MyClass {
private int m_Value = 0;
[NDORelation(RelationInfo.Composite)]
List myStuff = new List();
public void AddStuff(int val)
{
myStuff.Add(new Stuff(val));
}
... // Generate accessor functions and properties with the AddAccessor button.

public int Value{ get{ return m_Value; } }
}

I hope, that helps. If you have further questions, please ask.

Best Regards:
Mirko

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Persisting prim...