An error occurred while updating the entries savechanges
Find is also provided to read data by primary keys. Add and Add Range adds data to be created in the repository. Each entity’s tracking information is represented by a System. Later, the second query results a single product By Name entity too.
Remove and Remove Range remove data to be deleted in the repository. Entity Framework figures out product By Id and product By Name both map to the same data row of the same table, so product By Id and product By Name reference to the same entity in memory.
To track and save the changes, ii is attached to the repository.
As fore mentioned, the attached entity is tracked as Unchanged state, so just manually set its state to Modified..
This time product By Id and product By Name are independent from each other. Entities from different Db Context objects belong to different units of work, and do not interfere each other: The association of entities is also tracked.
Remember Product’s foreign key Product Subcategory ID is nullable.
Update(IEntity State Manager state Manager, IEntity Adapter adapter) at System. Db Cange Tracker object, which can track entities for the source Db Context object: The non generic Entries method returns the tracking information for all tracked entities. As fore mentioned in lazy load part, for a known entity, its tracking information can also be retrieved by calling Db Context. Db Entity Entry and Db Entity Entry The single product By Id entity from first LINQ to Entities query is tracked by Db Context. Db Entity Entry object: can be implicitly converted to Db Entity Entry.And essentially, each product’s Product Subcategory ID is changed to null, which is tracked: Db Context’s default behavior is to track all changes automatically. To disable tracking for specific entities read from repository, Entity Framework provides a As No Tracking extension method for IQueryable To change the data in the database, just create a Db Context object, change the data in its repositories, and call Db Context.Save Changes method to submit the tracked changes to the remote database as a unit of work.