DbContextScope

An instance of SmartDbContext has a short lifetime. It is retrieved from the pool when an HTTP request begins and is returned to the pool at the end of the request. To change the configuration of the request scoped context you can...:

1. Create a custom nested scope.

2. Do several actions within the scope.

3. Dispose the nested scope.

The context’s original state, as it was when you created the scope, is automatically restored when the scope is disposed. A custom scope is useful in scenarios where the default configuration of the data context does not fit your needs. For example:

• Disable automatic change detection in long-running operations, which slows down the more entities the change tracker contains.

• Speed up write access by disabling hook invocation, as both hook resolution and hook invocation take some time to process.

• Force the scope to be atomic, which saves all changes when the scope ends or is explicitly committed.

To create a scope where a DbContext instance behaves differently, use DbContextScope. The following code shows an excerpt from MediaService.Folder.cs.

using (var scope = new DbContextScope(_db, 
    autoDetectChanges: false,
    deferCommit: true))
{
    destinationPath += "/" + node.Value.Name;
    var dupeFiles = new List<DuplicateFileInfo>();

    // >>>> Do the heavy stuff
    var folder = await InternalCopyFolder(scope, node, destinationPath,
                            dupeEntryHandling, dupeFiles, cancelToken);

    var result = new FolderOperationResult
    {
        Operation = "copy",
	DuplicateEntryHandling = dupeEntryHandling,
	Folder = folder,
	DuplicateFiles = dupeFiles
    };

    return result;
}

Parameter reference

When initializing a DbContextScope instance, any non-null value will change the corresponding option for the duration of the scope. The db parameter is the only one required.

Parameter	Description
db	The data context instance to create scope for.
autoDetectChanges	Toggles EF's automatic entity change detection feature.
lazyLoading	Toggles EF's lazy loading feature.
forceNoTracking	If true, query results are not tracked, unless specified otherwise.
deferCommit	Suppresses the execution of SaveChanges until the scope is disposed or Commit is called explicitly. The default is false.
retainConnection	Opens a connection and retains it until the scope is closed. May increase load/save performance for large scopes. The default is false.
minHookImportance	Specifies the minimum hook importance level. Hooks below this level will not be executed.
cascadeDeleteTiming	Sets the CascadeDeleteTiming option in EF's change tracker.
deleteOrphansTiming	Sets the DeleteOrphansTiming option in EF's change tracker.