How to release tracked entities?

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Hopefully the following code snippet clear enough to explain the problem. _db is an instance of DbContext.

// this scenario is only for learning purpose
Author a = _db.Authors.Find(1831);
int id = a.AuthorId;
a = null;

Author stub = new Author { AuthorId = id };
_db.Remove(stub);
_db.SaveChanges();

The code above produces

'The instance of entity type 'Author' cannot be tracked because another instance with the same key value for {'AuthorId'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached. Consider using 'DbContextOptionsBuilder.EnableSensitiveDataLogging' to see the conflicting key values.'

Question

How to free a from being tracked?

There are a variety of ways to do this, but I find this the most simple since you're trying to detach a specific entity.

_db.Entry(a).State = EntityState.Detached

As a plus it doesn't require changing any other code, including however you fetched the entity itself.

This one line makes it very clear of the intent. It also allows the following:

  1. Fetch an entity, or list of entities
  2. Do various types of work
  3. Detach an entity

I dislike the idea of changing existing queries on a DbContext when all I want to do is detach something.

Tracking vs. No-Tracking Queries, You can add a method to your DbContext or an extension method that uses the ChangeTracker to detach all the Added, Modified, and Deleted� Although the entity is unchanged, it is still tracked in the context and is a part of set of entities that are considered during DetectChanges. E.g. you add new entity (it is in state Added), call SaveChanges and the added entity has now state Unchanged (it goes against the UnitOfWork pattern, but op asked: I am saving changes at the end of

You can try AsNoTracking(). _db.Authors.AsNoTracking().Where(a => a.AuthorId == 1831).FirstOrDefault();

[SOLVED], Entity Framework supports automatic change tracking of the loaded entities during the life-time of the context. Remove(std1); DisplayTrackedEntities(ctx. In standard scenario, all the entities selected from a database via EF are tracked. And tracking means that context ‘observes’ the tracked object and knows if it was changed. Thanks to that, when context uses tracking and we call context.SaveChanges(), changes will be applied to database.

You should use AsNoTracking option while querying for a.

e.g. Below query gets all blog items but if you try to delete them you should not get any error.

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

You can set AsNoTracking either on query or it can also be set on the context object as shown below:

context.ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking;

var blogs = context.Blogs.ToList();

This should help you to resolve this.

Refer this MSDN page for more details.

Change Tracking in Entity Framework, Learn how the ChangeTracker keeps track entities and their EntityState in Entity Framework Core. Remove method, then it will be marked as Deleted. You may need to track changes in a table or data entity for your own data staging or logging purposes. AIF framework has a change tracking feature which uses SQL server stored procedures to track data changes in AX tables, which is also the standard change tracking used by the DMF (DIXF) framework to handle incremental push of data.

ChangeTracker in Entity Framework Core, Entity Framework - Track Changes - Entity Framework provides ability to track the The Change Tracking tracks changes while adding new record(s) to the entity collection, modifying or removing existing entities. Remove(student); Console. Entity states. Tracked entities can be in one of four states. The state of an entity determines how it is processed when SaveChanges is called. Added: The entity does not yet exist in the database. SaveChanges should insert it. Unchanged: The entity exists in the database and has not been modified on the client. SaveChanges should ignore it.

Entity Framework - Track Changes, The Entity Framework Core changetracker is responsible for tracking changes made to entities and setting the current state of Add; Attach; Update; Remove. The Easy Entity Release manual and accompanying app is a comprehensive energy healing system that guides you to clear and release Dark Entities, Dark Entity Consciousness and Spirit Attachments from your energy field, physical body and subconscious mind.

The Entity Framework Core ChangeTracker, At the end I found out that it was due to the Entity Framework Core db Context tracking the state of the entities. More or less. In a nutshell, every� Minecraft tracks a lot of entities, even if they are outside the tracking range of the player, that's a normal behavior but is a tps killer for 1.14.4 to 1.16 servers with more than 30 players. So what this plugin do is untrack those entities every configured ticks and track them again if the player is near.

Comments
  • _db.Entry(a).State = EntityState.Detached
  • @Zer0: Thank you. It is very helpful. :-)
  • @Zer0: If you are not interested to post your comment as an answer, I will delete this question shortly. Thank you.
  • I will decide the accepted answer in a couple of hours.