实体框架保存更改

Question

Is there a point to save changes after a read only action? The entities are loaded to cache, but nothing changes, should save changes be called before dispose?

Answer 1

From doc ( DbContext.SaveChanges ) :

Saves all changes made in this context to the underlying database.

No there is no point in calling SaveChanges if you have not made any changes on your context.

You can read more about this in detail here

An entity can be in one of five states as defined by the EntityState enumeration. These states are:

• Added: the entity is being tracked by the context but does not yet exist in the database
• Unchanged: the entity is being tracked by the context and exists in the database, and its property values have not changed from the values in the database
• Modified: the entity is being tracked by the context and exists in the database, and some or all of its property values have been modified
• Deleted: the entity is being tracked by the context and exists in the database, but has been marked for deletion from the database the next time SaveChanges is called
• Detached: the entity is not being tracked by the context

SaveChanges does different things for entities in different states:

• Unchanged entities are not touched by SaveChanges. Updates are not sent to the database for entities in the Unchanged state.
• Added entities are inserted into the database and then become Unchanged when SaveChanges returns.
• Modified entities are updated in the database and then become Unchanged when SaveChanges returns.
• Deleted entities are deleted from the database and are then detached from the context.

Answer 2

除非你这样做，否则你不需要调用SaveChanges() ：

1. Add
2. Update
3. Delete