Entity Framework: `Remove()` vs. `DeleteObject()` – When to Use Which?

The difference and application of .Remove() and .DeleteObject() in Entity Framework

When using Entity Framework, you may encounter two different methods of deleting database items: EntityCollection.Remove() and ObjectContext.DeleteObject(). Although both aim to remove entities from the database, their functions and features are different.

EntityCollection.Remove()

This method removes the relationship between the parent entity and the child entity. In other words, it marks the relationship as deleted within the context without actually deleting the child entity itself. The EntityState of child entities remains unchanged.

Depending on the relationship between the parent entity and the child entity, the effect of using SaveChanges after calling .Remove() will be different:

• Optional relationships: The foreign key in the database is set to null, thus removing the relationship.
• Required non-identifying relationships: Thrown if no action is taken on the child entity (e.g., setting it to a different parent entity or explicitly deleting it) abnormal.
• Required identifying relationships: child entities will also be marked as deleted and removed from the database after SaveChanges.

ObjectContext.DeleteObject()

This method marks the specified entity in ObjectContext as deleted. The entity's EntityState is immediately set to Deleted. After calling SaveChanges, EF will send the SQL DELETE statement to the database. If all necessary conditions are met (for example, no reference constraints are violated), the entity is removed from the database.

When to use which method

• EntityCollection.Remove(): Used to remove the relationship between a parent entity and a child entity without explicitly deleting the child entity.
• ObjectContext.DeleteObject(): Used to directly delete an entity (mark it as deleted) and remove it from the database after SaveChanges.

Other notes

• .Remove() returns a Boolean value indicating success or failure, while .DeleteObject() returns void.
• If the relationship is required but not identified, then .Remove() may cause a constraint violation after SaveChanges.
• .DeleteObject() Explicitly mark the entity as deleted, ensuring it is removed from the database.

The above is the detailed content of Entity Framework: `Remove()` vs. `DeleteObject()` – When to Use Which?. For more information, please follow other related articles on the PHP Chinese website!