实体框架Include（）：指定的包含路径无效

Question

I have the following Entity Framework statement that has been working correctly.

CostingEvent targetEvent = repository.Query<CostingEvent>()
                                     .FirstOrDefault(ce => ce.Id == targetId);

However, I needed to disable lazy loading for this code and so I've added an Include() element to the previous statement:

CostingEvent targetEvent = repository.Query<CostingEvent>()
                                     .Include(ce => ce.ProposalSection.Proposal.Costing)
                                     .FirstOrDefault(ce => ce.Id == targetId);

However, this generates a run-time exception:

A specified Include path is not valid. The EntityType 'Leo.Domain.CostingEvent' does not declare a navigation property with the name 'Costing'.

I really don't understand this error. First of all, I am not referencing CostingEvent.Costing , I'm referencing CostingEvent.ProposalSection.Proposal.Costing . Furthermore, these are all valid navigation properties that show up in Intellisense.

Note: This is a database-first application. Also note: repository is a wrapper class but the Include() reference is standard Entity Framework.

Answer 1

Nested EF Includes are tricky.

Have you considered

CostingEvent targetEvent = repository.Query<CostingEvent>()
                                .Include("ProposalSection.Proposal.Costing")
                                .FirstOrDefault(ce => ce.Id == targetId);

This may also work

CostingEvent targetEvent = repository.Query<CostingEvent>()
                                .Include(ce => ce.ProposalSection)
                                .Include(ce => ce.ProposalSection.Proposal)
                                .Include(ce => ce.ProposalSection.Proposal.Costing)
                                .FirstOrDefault(ce => ce.Id == targetId);

Answer 2

You need to select the subnavigation properties like this:

CostingEvent targetEvent = repository.Query<CostingEvent>()
                                     .Include(ce => ce.ProposalSection.Select(ps=>ps.Proposal.Select(p=>p.Costing)))
                                     .FirstOrDefault(ce => ce.Id == targetId);