private static void CollectSelections(
IResolverContext context,
IFieldSelection selection,
ICollection <IFieldSelection> collected)
{
if (selection.Field.Type.IsLeafType())
{
collected.Add(selection);
}
if (selection.Field.Type.NamedType() is ObjectType objectType)
{
foreach (IFieldSelection child in context.GetSelections(
objectType, selection.SyntaxNode.SelectionSet))
{
CollectSelections(context, child, collected);
}
}
}
/// <summary>
/// TotalCount is one of the heaviest operations. It is only necessary to load totalCount
/// when it is enabled (IncludeTotalCount) and when it is contained in the selection set.
///
/// This method checks if the total count is selected
/// </summary>
/// <param name="context"></param>
/// <returns></returns>
public static bool IsTotalCountSelected(this IResolverContext context)
{
// TotalCount is one of the heaviest operations. It is only necessary to load totalCount
// when it is enabled (IncludeTotalCount) and when it is contained in the selection set.
if (context.Selection.Type is ObjectType objectType &&
context.Selection.SyntaxNode.SelectionSet is { } selectionSet)
{
IReadOnlyList <IFieldSelection> selections =
context.GetSelections(objectType, selectionSet, true);
for (var i = 0; i < selections.Count; i++)
{
if (selections[i].Field.Name.Value is ConnectionType.Names.TotalCount)
{
return(true);
}
}
}
return(false);
}
protected override async ValueTask <CollectionSegment> SliceAsync(
IResolverContext context,
object source,
OffsetPagingArguments arguments)
{
IQueryable <TItemType> queryable = source switch
{
IQueryable <TItemType> q => q,
IEnumerable <TItemType> e => e.AsQueryable(),
_ => throw new GraphQLException("Cannot handle the specified data source.")
};
IQueryable <TItemType> original = queryable;
if (arguments.Skip.HasValue)
{
queryable = queryable.Skip(arguments.Skip.Value);
}
queryable = queryable.Take(arguments.Take + 1);
List <TItemType> items =
await ExecuteQueryableAsync(queryable, context.RequestAborted)
.ConfigureAwait(false);
var pageInfo = new CollectionSegmentInfo(
items.Count == arguments.Take + 1,
(arguments.Skip ?? 0) > 0);
if (items.Count > arguments.Take)
{
items.RemoveAt(arguments.Take);
}
Func <CancellationToken, ValueTask <int> > getTotalCount =
ct => throw new InvalidOperationException();
// TotalCount is one of the heaviest operations. It is only necessary to load totalCount
// when it is enabled (IncludeTotalCount) and when it is contained in the selection set.
if (IncludeTotalCount &&
context.Field.Type is ObjectType objectType &&
context.FieldSelection.SelectionSet is {} selectionSet)
{
IReadOnlyList <IFieldSelection> selections = context
.GetSelections(objectType, selectionSet, true);
var includeTotalCount = false;
for (var i = 0; i < selections.Count; i++)
{
if (selections[i].Field.Name.Value is "totalCount")
{
includeTotalCount = true;
break;
}
}
// When totalCount is included in the selection set we prefetch it, then capture the
// count in a variable, to pass it into the clojure
if (includeTotalCount)
{
var captureCount = original.Count();
getTotalCount = ct => new ValueTask <int>(captureCount);
}
}
return(new CollectionSegment(
(IReadOnlyCollection <object>)items,
pageInfo,
getTotalCount));
}