Entity Framework POCO T4 sometimes creates an EntityCollection and sometimes creates a FixUpCollection

Question

I am having a strange problem with the POCO Entity Framework created by the POCO T4 templates. For some objects, their collection properties are created as EntityCollection , and for others they are created as FixUpCollection .

I find this with three classes that model the hierarchy of products; ProductGroup , Platform and Product . Each ProductGroup has a set of Platform s, and each Platform has a set of Product s. All relationships are bidirectional. The collectors and setters are the same for each class, because they are generated by the T4 template, so they all look (for example) as follows:

 public virtual ICollection<Platform> Platforms { get { if (_platforms == null) { var newCollection = new FixupCollection<Platform>(); newCollection.CollectionChanged += FixupPlatforms; _platforms = newCollection; } return _platforms; } set { ... } } 

The funny thing is that all collections on Product and Platform are created as EntityCollection s, and all collections on ProductGroup are created as FixUpCollection s. those. when the code first enters the getter (e.g. Platform.Products ), the _products field _products already filled with the EntityCollection symbol, but when it first enters the getter shown above, _platforms is null and a FixUpCollection is created and then populated. Lazy-load works in both cases, it just works differently.

Entities has the ability to create lazy loading and proxies. Product , Platform and CoreProduct are all dynamic EF proxies in the Entity.DynamicProxies namespace. I tried very hard to load Platform and ProductGroup , which did not matter. I see no difference in how the classes are configured in the model viewer.

It causes me a headache, because one of the collections in the ProductGroup contains thousands of objects, and I want to request this collection. As far as I know (please correct me if I am wrong). I cannot request FixUpCollection without loading all the objects into memory, which is not the case with EntityCollection , because I can use CreateSourceQuery() . Has anyone seen this behavior before? Are there any settings that I am missing somewhere? Any pointers or help would be greatly appreciated.

Answer 1

I cannot request FixUpCollection without loading all objects in memory, which is not the case with EntityCollection.

In terms of queries, there is no difference between FixUpCollection and EntityCollection . EntityCollection used by a dynamic proxy server for lazy loading, and if you try to request a property of this type, lazy loading will still load all records and the request will be executed as Linq-to-objects.

Your problem is most likely due to a violation of some rule for creating a lazy loding proxy.