CODEWITHSUNDEEP
asp.netentity-framework.net-coreef-core-3.0
JB's
JB's

Reputation: 626

Entity Framework Navigation Properties data refreshed/updated with second DB calls

Query from EF results a complex Entity that has few associated properties and some are null. When I call DB to get details of those associated complex objects, EF pumps data into my first collection, where previously data was null. And it causes a self-referencing issue when converting to JSON.

Say a student has many Courses and courses have instructors. And a course also has a list of students. When I get courses of a student it gives me a collection of those student courses where student.Courses is null. Now when I get a collection of all courses from DB. student.Courses is now no more null. It has a list of courses.

I have 2 Questions

  1. How to control this behavior in a way that collection one is not updated.
  2. How to avoid self-referencing issue.

I am on dot-net core 3. And I have SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore; in place.

I want to avoid EF from doing the following

Entity Framework Core will automatically fix-up navigation properties to any other entities that were previously loaded into the context instance. So even if you don't explicitly include the data for a navigation property, the property may still be populated if some or all of the related entities were previously loaded.Ref

Upvotes: 0

Views: 50

Answers (1)

David Browne - Microsoft
David Browne - Microsoft

Reputation: 89386

How to control this behavior in a way that collection one is not updated.

Load your entities using No-tracking queries.

No tracking queries are useful when the results are used in a read-only scenario. They're quicker to execute because there's no need to set up the change tracking information. If you don't need to update the entities retrieved from the database, then a no-tracking query should be used. You can swap an individual query to be no-tracking.

var blogs = context.Blogs
    .AsNoTracking()
    .ToList();

You can also change the default tracking behavior at the context instance level:

context.ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking;

var blogs = context.Blogs.ToList();

https://learn.microsoft.com/en-us/ef/core/querying/tracking

Upvotes: 1

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