Transaction
In Entity Framework, when you call SaveChanges() to insert, delete, or update data to the database, the entity framework will wrap that operation in a transaction.
- The transaction allows several database operations to be processed atomically.
- If it is committed, all of the operations are successfully applied to the database.
- If the transaction is rolled back, none of the operations are applied to the database.
Default Behaviour
- In Entity Framework,
SaveChangesautomatically starts a transaction and commits or rolls it back. - It means the Entity Framework maintains a transaction for the multiple entity inserts, update and delete in a single
SaveChanges()method. - When we execute another operation, the Entity Framework creates a new transaction.
The following example saves two author entities by calling SaveChanges() for each entity.
using (var context = new BookStore()) { context.Database.Log = Console.WriteLine; Author author1 = new Author() { Name = "Mark" }; Author author2 = new Author() { Name = "John" }; context.Authors.Add(author1); context.SaveChanges(); context.Authors.Add(author2); context.SaveChanges(); }
You can see that EF saves both entities in separate transactions.
Opened connection at 10/29/2018 9:18:26 AM +00:00 Started transaction at 10/29/2018 9:18:26 AM +00:00 INSERT [dbo].[Authors]([Name]) VALUES (@0) SELECT [AuthorId] FROM [dbo].[Authors] WHERE @@ROWCOUNT > 0 AND [AuthorId] = scope_identity() -- @0: 'Mark' (Type = String, Size = -1) -- Executing at 10/29/2018 9:18:26 AM +00:00 -- Completed in 3 ms with result: SqlDataReader Committed transaction at 10/29/2018 9:18:26 AM +00:00 Closed connection at 10/29/2018 9:18:26 AM +00:00 Opened connection at 10/29/2018 9:18:26 AM +00:00 Started transaction at 10/29/2018 9:18:26 AM +00:00 INSERT [dbo].[Authors]([Name]) VALUES (@0) SELECT [AuthorId] FROM [dbo].[Authors] WHERE @@ROWCOUNT > 0 AND [AuthorId] = scope_identity() -- @0: 'John' (Type = String, Size = -1) -- Executing at 10/29/2018 9:18:26 AM +00:00 -- Completed in 1 ms with result: SqlDataReader Committed transaction at 10/29/2018 9:18:26 AM +00:00 Closed connection at 10/29/2018 9:18:26 AM +00:00
Multiple Operations in Single Transaction
You can use multiple SaveChanges within a single transaction as shown below;
using (var context = new BookStore()) { context.Database.Log = Console.WriteLine; using (DbContextTransaction transaction = context.Database.BeginTransaction()) { try { Author author1 = new Author() { Name = "Mark" }; Author author2 = new Author() { Name = "John" }; context.Authors.Add(author1); context.SaveChanges(); context.Authors.Add(author2); context.SaveChanges(); transaction.Commit(); } catch (Exception ex) { transaction.Rollback(); } } }
You can see that both author entities are saved to the database in one transaction.
Opened connection at 10/29/2018 9:21:20 AM +00:00 Started transaction at 10/29/2018 9:21:20 AM +00:00 INSERT [dbo].[Authors]([Name]) VALUES (@0) SELECT [AuthorId] FROM [dbo].[Authors] WHERE @@ROWCOUNT > 0 AND [AuthorId] = scope_identity() -- @0: 'Mark' (Type = String, Size = -1) -- Executing at 10/29/2018 9:21:20 AM +00:00 -- Completed in 3 ms with result: SqlDataReader INSERT [dbo].[Authors]([Name]) VALUES (@0) SELECT [AuthorId] FROM [dbo].[Authors] WHERE @@ROWCOUNT > 0 AND [AuthorId] = scope_identity() -- @0: 'John' (Type = String, Size = -1) -- Executing at 10/29/2018 9:21:20 AM +00:00 -- Completed in 0 ms with result: SqlDataReader Committed transaction at 10/29/2018 9:21:20 AM +00:00 Closed connection at 10/29/2018 9:21:20 AM +00:00
