Entity Framework: `EntityCollection.Remove()` vs. `ObjectContext.DeleteObject()` – Which Method Should I Use?

Comparison of entity deletion methods in Entity Framework

Entity Framework provides two main methods to delete items from the database: EntityCollection.Remove() and ObjectContext.DeleteObject(). Although both delete items from the database, their functionality and usage differ.

EntityCollection.Remove()

EntityCollection.Remove() Delete the relationship between parent entity and child entity. This method marks the relationship as deleted in the context. If the child entity itself has been deleted, the exact action taken when SaveChanges is called depends on the nature of the relationship:

• Optional relationship: The foreign key from the parent entity to the child entity is set to null and the updated value is written to the database using a SQL UPDATE statement.
• Required non-identifying relationship: requires additional action, such as reassigning the child entity to a different parent entity or calling DeleteObject() on the child entity. Otherwise, a reference constraint violation exception will result.
• Required identification relationship: The child entity is also marked as deleted. Calling SaveChanges will send a SQL DELETE statement to the database, deleting the child entity if no referential constraints are violated.

ObjectContext.DeleteObject()

ObjectContext.DeleteObject() Marks the entity as deleted in the context. This sets the entity's EntityState to Deleted, distinguishing it from other entities that may have relationships marked as deleted but not themselves deleted. Calling DeleteObject() after using SaveChanges will trigger a SQL DELETE statement to delete the entity from the database, provided no referential constraints are violated.

Return value

It is important to note that EntityCollection.Remove() returns a bool value indicating whether the relationship has been successfully deleted, while ObjectContext.DeleteObject() returns void.

Usage suggestions

Which method to use depends on the desired result. EntityCollection.Remove() is applicable if the goal is to delete the relationship between two entities without deleting the child entities. For deleting the entity itself, ObjectContext.DeleteObject() should be used, especially if referential constraints may be violated.

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