Entity Framework throwing error when fetching a nested object using .include

Question

I have a query here that fetches a single entity object and only one nested entity that meets a specific condition, but I'm receiving an error when executing it.

Here is the query

Profile profile = dbContext.Profiles.Where(i => i.ApplicationUserGuid == guiId)
               .Include(i => i.ProfileImages.Where(k => k.IsMainImage == true)).First();

And here is the exception error message

The Include path expression must refer to a navigation property defined on the type. Use dotted paths for reference navigation properties and the Select operator for collection navigation properties. Parameter name: path

I also tried running it with another .First(), but still same error message

Profile profile = dbContext.Profiles.Where(i => i.ApplicationUserGuid == guiId)
              .Include(i => i.ProfileImages.Where(k => k.IsMainImage == true).First()).First();

Community · Accepted Answer · 2017-05-23 12:13:45Z

2

You can't filter related entities inside an Include, you are going to need to project your query with the expected result or use explicit loading:

Profile profile = dbContext.Profiles
                           .Where(i => i.ApplicationUserGuid == guiId)
                           .First();
dbContext.Entry(profile) //Explicit Loading
         .Collection(b => b.ProfileImages) 
         .Query() 
         .Where(k => k.IsMainImage == true).Take(1)
         .Load();

If you do the projection it will be only one round trip to your database, and if you use explicit loading it will be two.

Just a FYI, in case you think to project the result, project to an anonymous type or onto a DTO. More info here.

edited May 23, 2017 at 12:13

CommunityBot

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answered Nov 18, 2016 at 21:46

ocuenca

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19 Comments

chuckd Over a year ago

I'm following your explicit loading example and its working but it's returning all the nested entities and not just the one that meets the where condition!

ocuenca Over a year ago

I have edited my answer, Take method should fix that

chuckd Over a year ago

I'm still a little unsure why all images are being returned when all except 1 meet the where condition? Then what's the purpose of the where condition? If it's not working? And I tried Take(1) and it still returns all the images!

ocuenca Over a year ago

Oh, just one meet the condition? Are you completely sure? Did you check your db?

ocuenca Over a year ago

What I always do is disable lazy loading and use eager loading instead when I need some nav prop, but maybe your design works better with lazy loading. That property is being loaded because it has been accessed in some point in your code. Projecting your queries to ViewModel classes is a good practice, you will find good tutorials if your search a little.

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