Andrew Peters’ Blog

Alex has been thinking a bit about object eager-loading (prefetch) retrieval strategies recently.

The LINQ to SQL approach of using a Lambda is interesting and was the approach we used on BackgroundMotion:

Contribution contribution = Repository<Contribution>
      .Find(1)
      .Including(c => c.ContributionTags);

What’s more interesting to me however is that now we have a way to refer to symbols in a type safe way. Useful for things like data binding etc. where we want to specify a property and where currently we have to use a string. That’s not to say that this Lambda syntax is optimal for this but what can you do? :-)

With respect to eager load strategies our new domain model/persistence framework LightSpeed has the notion of a “named aggregate” - aggregate being a term taken from Domain-driven design. Basically we use an attribute called EagerLoad at the association level in the model:

[EagerLoad(AggregateName="ContributionDetail")]
public readonly EntityCollection<ContributionTag> _contributionTags
  = new EntityCollection<ContributionTag>();

Then we can specify an aggregate name as part of our query.

Query query = new Query(Entity.Attribute("Title").Like("A%"));
query.AggregateName = "ContributionDetail";
IList<Contribution> contributions = Repository.Find<Contribution>(query);

The key point is that we are being explicit about naming the aggregates.