Anyone who has worked with Entity Framework will have had to manage with loading related entities. I believe many developers will agree the way that system works is difficult to reconcile with design patterns such as the Repository pattern. In this post, I’ll provide one quick and easy way to automatically load all related properties from the database.
Update 2018-11-26: Added the equivalent for EF Core.
By default, Entity Framework will load all “simple” types such as integers or string values. On the other, custom types such as the collection of Post objects aren’t in scope by default and will be null.
Of course, there is a method called “Include” that you can use to instruct Entity Framework to load the property with the specified parameter in the object graph:
You can add as many includes as you want, as long as you provide a property name. This doesn’t work very well if you are planning to implement a generic repository pattern. Because you don’t know the objects you’re working with, you can’t provide the names of your properties. And this is something you don’t want to know if you’re trying to make something generic.
Instead, I have a solution that automatically loads all navigation properties to the graph. If one of your requirements is performance, this probably won’t be the best solution. For that, I recommend you to look into query projections. Instead, if you want to have a comfortable way of accessing fully populated data, this is your answer.
Here is an example of a query that fetches the data with the possibility of adding a filter:
As you can see, this code sample also uses the Include statement, but it’s retrieving the parameters in runtime. Using the EF API, the current type is inspected and only the properties that are EntityTypes according to EF are included manually in the query. This code snippet offers some interesting perspectives to make it even more dynamic. Everything you see here is pure Entity Framework, no workarounds or whatsoever, so I like to think this as a sustainable solution.
For Entity Framework Core 2.0, this is the equivalent: