问题
EF Core 2.1 introduced support for ambient transactions. The sample creates a new SqlConnection
, manually opens it and passes it to the DbContext
:
using (var scope = new TransactionScope(
TransactionScopeOption.Required,
new TransactionOptions { IsolationLevel = IsolationLevel.ReadCommitted }))
{
var connection = new SqlConnection(connectionString);
connection.Open();
try
{
// Run raw ADO.NET command in the transaction
var command = connection.CreateCommand();
command.CommandText = "DELETE FROM dbo.Blogs";
command.ExecuteNonQuery();
// Run an EF Core command in the transaction
var options = new DbContextOptionsBuilder<BloggingContext>()
.UseSqlServer(connection)
.Options;
using (var context = new BloggingContext(options))
{
context.Blogs.Add(new Blog { Url = "http://blogs.msdn.com/dotnet" });
context.SaveChanges();
}
// Commit transaction if all commands succeed, transaction will auto-rollback
// when disposed if either commands fails
scope.Complete();
}
catch (System.Exception)
{
// TODO: Handle failure
}
}
There is no call to connection.Close()
though.
Is this part just missing in the sample or is the connection closed automatically somehow when the TransactionScope
or the DbContext
are disposed?
Edit: The call to Close/Dispose was missing. I filed a pull request and the docs are updated now.
回答1:
The behavior seems to be unrelated to ambient transactions, but the answer of the question who owns the DbConnection
passed to a DbContext
.
EF6 DbContext
constructor accepting DbConnection
has bool contextOwnsConnection
parameter for explicitly specifying that.
But how about EF Core? There is no such parameter on UseXyz
methods accepting DbConnection
.
The rule seems to be the as follows, taken from UseSqlServer method connection
parameter documentation:
If the connection is in the open state then EF will not open or close the connection. If the connection is in the closed state then EF will open and close the connection as needed.
Which I read "If the passed connection is not opened, EF Core will take the ownership, otherwise the ownership is left to the caller".
Since the example calls connection.Open();
before UseSqlServer(connection)
, I would assume you are responsible for closing/disposing it, so I would consider the example being incorrect.
回答2:
For safeside use using so that the connection is disposed.
using(var connection = new SqlConnection(connectionString)) {
....
}
来源:https://stackoverflow.com/questions/51239326/do-i-need-to-close-the-dbconnection-manually-when-using-ambient-transactions-wit