Object Factories with Lazy Loading in C#

[cebyrjoe2]

I'm looking for a lazy loading solution in c#. The idea is, to have a kind of object factory, which will be responsible for creating my entity objects. When a property of such an object is accesed and it is not yet loaded, the factory (or a magic watcher) will be able to pause the execution flow for a while (maybe that step is not necessary) load the missing data (don't know how to specify, from where to load that data----maybe via attributes) and return to the flow. My entity objects, do not have a possibility to load the missing data by themselves, because they are only data containers having private members, which are accessible via public properties. These objects need to be filled with their data from outside, and therefore many lazy loading solutions won't work here. Maybe anyone of you knows the solution for my problem? Thank You in advance! Greetz! cyberjoe

[Colin Angus Mackay]

cebyrjoe2 wrote:

The idea is, to have a kind of object factory, which will be responsible for creating my entity objects. When a property of such an object is accesed and it is not yet loaded, the factory (or a magic watcher) will be able to pause the execution flow for a while (maybe that step is not necessary) load the missing data (don't know how to specify, from where to load that data----maybe via attributes) and return to the flow.

Have you considered using properties?

public class MyClass
{
private bool isLazyLoaded;
private string someData;

public string SomeData
{
    get
    {
        DoLazyLoadIfNecessary();
        return this.someData;
    }
}

private void DoLazyLoadIfNecessary()
{
    if (!isLazyLoaded)
    {
        // Do what ever is necessary to get the values.
    } 
}

}

Once you have this only the code that does the lazy load will access the lazy loaded fields directly. Everything else goes through the property.

cebyrjoe2 wrote:

My entity objects, do not have a possibility to load the missing data by themselves, because they are only data containers having private members, which are accessible via public properties. These objects need to be filled with their data from outside, and therefore many lazy loading solutions won't work here.

I should have read the whole thing before typing out that example - Sod it, I've typed it now so I'm keeping it! :-D Each object will need to know at least an ID so that it can go and request its data from a DAL or some such thing. Many of my objects have lazy load functionality, when they are created all that is known about them is a corresponding database ID. For any lazy load solution to work some sort of identifier needs to be known.

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