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I'm using the Repository pattern with DI and IoC.

I have created a function in my Repository:

T EagerGetById<T>(Guid id, string include) where T : class { return _dbContext.Set<T>().Include(include).Find(id); }

This will eagerly load one navigation property in my entity right.

But if my entity looks like this:

public class Blog : PrimaryKey { public Author Author {get;set;} public ICollection<Post> Posts {get;set;} }

How would I get eager loading for Author and Posts? Would I literally have to do:

_dbContext.Set<T>().Include("Author").Include("Posts").Find(id);

inevitably producing a function like this:

T EagerGetById<T>(Guid id, string include, string include2, string include3) where T : class { return _dbContext.Set<T>().Include(include).Include(include2).Include(include3).Find(id); }

Because that would be really inefficient for a Generic Repository!

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2 Answers 2

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27

If you don't want to use strings, you can also do the same for any N number of includes by using an expression which returns the navigation properties to be eager loaded. (original source here)

public IQueryable<TEntity> GetAllIncluding(params Expression<Func<TEntity, object>>[] includeProperties) { IQueryable<TEntity> queryable = GetAll();    foreach (Expression<Func<TEntity, object>> includeProperty in includeProperties) {     queryable = queryable.Include<TEntity, object>(includeProperty);    } return queryable; }
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5 Comments

I was actually thinking about doing that, but is it easy in Repository pattern with DI and IoC??
On 2nd glance... context.Configuration.ProxyCreationEnabled = false; doesn't force eager loading. It just turns of proxy creation. You'd still need to do the include. I'm editing it out of the answer.
does that make sense.... what is the point in enabling proxy creation, what benefits does it give?!
Proxy creation enables lazy loading of virtual properties. Essentially EF will put "stand in classes" for the navigation properties that hit the database when accessed. If proxy generation isn't enabled, those the child objects that haven't been "included" in the query will appear null and EF won't hit the db behind the scenes to do lazy loading.
I'm having a difficult time understanding this implementation. Can you give a usage example?
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If you need all navigation properties, you have no choice but to read all of them from the database. You either Include them in your query, or read them in advance to the DbSet's local data.

If you want to pass multiple includes to your method, just define it like this:

T EagerGetById<T>(Guid id, params string[] includes)

Your users will be able to call EagerGetById(id, "inc1", "inc2", ...)

Inside your method, just call Include for every element in the includes array.

You should ready about the params keyword

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4 Comments

See edits, specifically the new kind of function that would have to be created for this...
Oh, that's not inefficient, it's just ugly. I'll edited my response.
i know all about params.. still didnt really answer the question! Sorry dude, this hasn't cut it!
For the record, @zmbq 's answer was just fine. It seems you didn't get it. The accepted answer is almost literally the same thing. It's just, arguably, more 'clean' to use property references instead of property names.

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