如何合并两个表达式树体？

Question

If I have:

m => m.OwnedCollection(p => p.Addresses)

and

m => m.OwnedCollection(p => p.Contacts)

I'd like to combine them to be:

m => m.OwnedCollection(p => p.Addresses).OwnedCollection(p => p.Contacts)

Is there a way of doing this?

I'd also like to be able to combine:

m => m.OwnedCollection(p => p.Contacts)

and:

with => with.AssociatedCollection(p => p.AdvertisementOptions)

to be:

m => m.OwnedCollection(p => p.Contacts, with => with.AssociatedCollection(p => p.AdvertisementOptions))

Is there a way of doing this one as well?

I'm hoping that these are fairly simple requirements but I'm finding it difficult to get to grips with the terminology.

Some background:

I'm using https://github.com/refactorthis/GraphDiff to support merging of entities for updates. The problem is that it expects an expression tree describing the relationships of the enitity to be updated eg.

context.UpdateGraph(company, map => map
    .OwnedCollection(p => p.Contacts, with => with
        .AssociatedCollection(p => p.AdvertisementOptions))
    .OwnedCollection(p => p.Addresses)
);

Mine needs to be a generic solution, so I need to examine the various one-to-one, one-to-many and many-to-many relationships of my entities type using reflection and convert these to an expression tree.

Any help on my specific questions or general help would be appreciated.

Answer 1

The develop branch of GraphDiff provides support for attribute based mapping. Instead of providing an expression tree mapping your graph, you add custom attributes ( Owned or Associated ) to the navigation properties in your model classes and GraphDiff creates the mapping for you. Have a look at GraphDiffs test models for some examples of this.