/// <summary>
/// Traverse an object graph asynchronously executing a callback on each node.
/// Depends on Entity Framework Core infrastructure, which may change in future releases.
/// </summary>
/// <param name="context">Used to query and save changes to a database</param>
/// <param name="item">Object that implements ITrackable</param>
/// <param name="callback">Async callback executed on each node in the object graph</param>
public static async Task TraverseGraphAsync(this DbContext context, object item,
Func <EntityEntryGraphNode, Task> callback)
{
IStateManager stateManager = context.Entry(item).GetInfrastructure().StateManager;
var node = new EntityEntryGraphNode(stateManager.GetOrCreateEntry(item), null, null);
IEntityEntryGraphIterator graphIterator = new EntityEntryGraphIterator();
var visited = new HashSet <int>();
await graphIterator.TraverseGraphAsync(node, async (n, ct) =>
{
// Check visited
if (visited.Contains(n.Entry.Entity.GetHashCode()))
{
return(false);
}
// Execute callback
await callback(n);
// Add visited
visited.Add(n.Entry.Entity.GetHashCode());
// Return true if node state is null
return(true);
});
}
/// <summary>
/// Traverse an object graph asynchronously executing a callback on each node.
/// </summary>
/// <param name="context">Used to query and save changes to a database</param>
/// <param name="item">Object that implements ITrackable</param>
/// <param name="callback">Async callback executed on each node in the object graph</param>
public static async Task TraverseGraphAsync(this DbContext context, object item,
Func <EntityEntryGraphNode, Task> callback)
{
#pragma warning disable EF1001 // Internal EF Core API usage.
IStateManager stateManager = context.Entry(item).GetInfrastructure().StateManager;
var node = new EntityEntryGraphNode <object>(stateManager.GetOrCreateEntry(item), null, null, null);
IEntityEntryGraphIterator graphIterator = new EntityEntryGraphIterator();
#pragma warning restore EF1001 // Internal EF Core API usage.
var visited = new HashSet <int>();
await graphIterator.TraverseGraphAsync <object>(node, async (n, ct) =>
{
// Check visited
if (visited.Contains(n.Entry.Entity.GetHashCode()))
{
return(false);
}
// Execute callback
await callback(n);
// Add visited
visited.Add(n.Entry.Entity.GetHashCode());
// Continue traversal
return(true);
});
}
/// <summary>
/// Traverse an entity graph asynchronously executing a callback on each node.
/// </summary>
/// <param name="context">The entity graph context.</param>
/// <param name="entity">The entity to start traversing the graph from.</param>
/// <param name="callback">The asynchronous callback executed on each node in the entity graph.</param>
/// <param name="cancellationToken">A System.Threading.CancellationToken to observe while waiting for the task to complete.</param>
public static Task TraverseGraphAsync(this DbContext context, object entity, Func <EntityEntryGraphNode, CancellationToken, Task> callback, CancellationToken cancellationToken = default)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
if (callback == null)
{
throw new ArgumentNullException(nameof(callback));
}
#pragma warning disable EF1001 // Internal EF Core API usage.
var graph = new EntityEntryGraphIterator( );
var visited = new HashSet <object> ( );
var entry = context.Entry(entity).GetInfrastructure( );
var root = new EntityEntryGraphNode <object?> (entry, null, null, null);
return(graph.TraverseGraphAsync(root,
async(node, cancellationToken) =>
{
if (!visited.Add(node.Entry.Entity))
{
return false;
}
await callback(node, cancellationToken).ConfigureAwait(false);
return true;
},
cancellationToken));
#pragma warning restore EF1001 // Internal EF Core API usage.
}