Hi folks:

There is some way to get a DataView from a LLBLGenProDataSource2?

I need that to export the Datasource data to a excel sheet.

Regards and thank you very much.

Hi there. Try this:

// first, create a view based on the actual fetched collection on the LLBLGenProDataSource
IEntityView2 view = _llblgenProDS.EntityCollection.DefaultView;

// create the propertyProjectors.
List<IEntityPropertyProjector> propertyProjectors = new List<IEntityPropertyProjector>();
foreach (EntityField2 field in _llblgenProDS.EntityCollection.EntityFactoryToUse.CreateFields())
{
    propertyProjectors.Add(new EntityPropertyProjector(field, field.Name));
}

// the dataTable to fill
DataTable projectionResults = new DataTable();

// create the actual projection.
view.CreateProjection(propertyProjectors, projectionResults);

Daelmo:

Thanks for the quick response.

That solution does not include prefetch paths. I need to get exactly the same contents of the datasource and not only the data from entities.

Thank you very much. Regards.

Please check the example of Hierarchical projections .

Walaa:

I've checked the example but i was not able to project any prefetch path at all.

The problem with this code,

        foreach (IPrefetchPathElement2 pre in _InstrumentDS.PrefetchPathToUse)
            foreach (EntityField2 fie in pre.EntityFactoryToUse.CreateFields())
                propertyProjectors.Add(new EntityPropertyProjector(fie, fie.Name));

is pre.EntityFactoryToUse == null

Any ideas?

Thank you very much. Regards.

If you set the datasource to some prefetch path, you can use that same prefetch path to fetch the projection.

Ok, the problem is:

I cannot get the prefetchpath fields, bcoz the EntityFactoryToUse is null.

Can you please post example code?

Regards.

pvilanova wrote:

Walaa:

I've checked the example but i was not able to project any prefetch path at all.

The problem with this code,

        foreach (IPrefetchPathElement2 pre in _InstrumentDS.PrefetchPathToUse)
            foreach (EntityField2 fie in pre.EntityFactoryToUse.CreateFields())
                propertyProjectors.Add(new EntityPropertyProjector(fie, fie.Name));

is pre.EntityFactoryToUse == null

Any ideas?

Thank you very much. Regards.

Are you sure you tried the Hierarchical Projection example? coz that indeed should work:

// -- the projectionData to fill
List<IViewProjectionData> projectionData = new List<IViewProjectionData>();


// -- setup projections per type.

// customers (the root type)
List<IEntityPropertyProjector> customerProjections = EntityFields2.ConvertToProjectors(
        EntityFieldsFactory.CreateEntityFieldsObject(EntityType.CustomersEntity));
projectionData.Add(new ViewProjectionData<CustomersEntity>(customerProjections, null, true));

// orders
List<IEntityPropertyProjector> orderProjections = EntityFields2.ConvertToProjectors(
        EntityFieldsFactory.CreateEntityFieldsObject(EntityType.OrdersEntity));
projectionData.Add(new ViewProjectionData<OrdersEntity>(orderProjections, null, false));

// employee
List<IEntityPropertyProjector> employeeProjections = EntityFields2.ConvertToProjectors(
        EntityFieldsFactory.CreateEntityFieldsObject(EntityType.OrderDetailsEntity));
projectionData.Add(new ViewProjectionData<OrderDetailsEntity>(employeeProjections));


// -- get the DataSet results (here, _customerDS is a LLBLGenProDataSource2                     
DataSet result = new DataSet("projectionResult");
_customersDS.EntityCollection.CreateHierarchicalProjection(projectionData, result);

That assumes:

• The data is fetched and ready to use in your LLBLGenProDataSource2
• You know the prefetched graph and what types of that graph you want to project to the result DataSet.

Also, as you want a Hierarchical projection (root entity + prefetchtPaths) the result should be a DataSet, not a DataView

Hope helpful

To follow-up on what pvilanova wrote, is there a recommended way of converting prefetched entities w/in a collection into a projected dataTable automatically? In otherwords, I'd like to pass an entity collection into a method and have it and all prefetched entities converted into a dataTabe.

The above recommendation would seem to only work where I know beforehand what entities are prefetched.

Thanks!

pvilanova wrote: Walaa:

I've checked the example but i was not able to project any prefetch path at all.

The problem with this code, Code: foreach (IPrefetchPathElement2 pre in _InstrumentDS.PrefetchPathToUse) foreach (EntityField2 fie in pre.EntityFactoryToUse.CreateFields()) propertyProjectors.Add(new EntityPropertyProjector(fie, fie.Name));

is pre.EntityFactoryToUse == null

Any ideas?

Thank you very much. Regards.

The above recommendation would seem to only work where I know beforehand what entities are prefetched.

If you don't know the prefetched entities beforehand.

Then you'd have to do it manually: 1- Looping on the passed in collection and calling each entity's GetDependingRelatedEntities() & GetDependentRelatedEntities() methods, to get the attached related entities.

Please check the reference manual for these methods.

2- then you'll have to use the EntityField collection (entity.Fields) to loop on fields and start copying data into datatables.

Hi Walaa, thank you for the reply. The suggestion you provide is very useful. However, I was wondering if it would be more efficient to pass to my function a hint as to which prefetched entities to project into the dataTable. For example, if I were to pass the same prefetchPath2 collection as used to fetch the entityCollection in the first place. This is why I was interested in the earlier poster's suggestion about iterating through the prefetch elements.

Is there a way to get the fields from prefetch entities based on the prefetchpath passed? The earlier suggestion of prefetchPAthElement.EntityFactoryToUse.CreateFields() does not seem to work since the entitfactoryToUse is null.

Thanks!

this the following function give an idea of what I'm trying to achieve:

public DataTable CollectionToDataTable<TEntity>(EntityCollection<TEntity> collection, IPrefetchPath2 pp) where TEntity : EntityBase2, IEntity2
{
    // fields for the base element
    List<IEntityPropertyProjector> propertyProjectors = EntityFields2.ConvertToProjectors(collection.EntityFactoryToUse.CreateFields());
    
    // fields for each prefetched element
    if (pp != null && pp.Count != 0)
    {
        for (int i = 0; i < pp.Count; i++)
        {
            // ERROR! this is where the error occurs, since EntityFactoryToUse is always null for prefetch paths
            // questio is how to get the entity fields from these prefetched entities
            foreach (IEntityField2 f in pp[i].EntityFactoryToUse.CreateFields())
            {
                propertyProjectors.Add(new EntityPropertyProjector(f, pp[i].EntityFactoryToUse.ForEntityName + f.Name));
            }
        }
    }
    DataTable dt = new DataTable();
    collection.DefaultView.CreateProjection(propertyProjectors, dt);
    return dt;
}

Note int he above comments where the error occurs in converting prefetched entities into fields collections for projection

please ignore the previous post, I now realize that the collection.DefaultView.CreateProjection(propertyProjectors, dt) function will not pull data from the prefetched entities, only the base entity from the entityCollection. Back to the drawing board