public Connection( IReadOnlyCollection <Edge <T> > edges, ConnectionPageInfo info, Func <CancellationToken, ValueTask <int> > getTotalCount) : base(edges, info, getTotalCount) { Edges = edges; }
public Connection( IReadOnlyCollection <IEdge> edges, ConnectionPageInfo info, Func <CancellationToken, ValueTask <int> > getTotalCount) { _getTotalCount = getTotalCount ?? throw new ArgumentNullException(nameof(getTotalCount)); Edges = edges ?? throw new ArgumentNullException(nameof(edges)); Info = info ?? throw new ArgumentNullException(nameof(info)); }
protected override ValueTask <Connection> SliceAsync(IResolverContext context, object source, CursorPagingArguments arguments) { //If Appropriate we handle the values here to ensure that no post-processing is done other than // correctly mapping the results into a GraphQL Connection as Edges with Cursors... if (source is IPreProcessedCursorSlice <TEntity> pagedResults) { bool includeTotalCountEnabled = this.PagingOptions.IncludeTotalCount ?? PagingDefaults.IncludeTotalCount; var graphQLParamsContext = new GraphQLParamsContext(context); //Optimized to only require TotalCount value if the query actually requested it! if (includeTotalCountEnabled && graphQLParamsContext.IsTotalCountRequested && pagedResults.TotalCount == null) { throw new InvalidOperationException($"Total Count is requested in the query, but was not provided with the results [{this.GetType().GetTypeName()}] from the resolvers pre-processing logic; TotalCount is null."); } int?totalCount = pagedResults.TotalCount; //Ensure we are null safe and return a valid empty list by default. IReadOnlyList <IndexEdge <TEntity> > selectedEdges = pagedResults?.ToEdgeResults().ToList() ?? new List <IndexEdge <TEntity> >();; IndexEdge <TEntity>?firstEdge = selectedEdges.FirstOrDefault(); IndexEdge <TEntity>?lastEdge = selectedEdges.LastOrDefault(); var connectionPageInfo = new ConnectionPageInfo( hasNextPage: pagedResults?.HasNextPage ?? false, hasPreviousPage: pagedResults?.HasPreviousPage ?? false, startCursor: firstEdge?.Cursor, endCursor: lastEdge?.Cursor, totalCount: totalCount ?? 0 ); var graphQLConnection = new Connection <TEntity>( selectedEdges, connectionPageInfo, ct => new ValueTask <int>(connectionPageInfo.TotalCount ?? 0) ); return(new ValueTask <Connection>(graphQLConnection)); } throw new GraphQLException($"[{nameof(PreProcessedCursorPagingHandler<TEntity>)}] cannot handle the specified data source of type [{source.GetType().Name}]."); }
/// <summary> /// Applies the pagination algorithm to the provided query. /// </summary> /// <param name="query">The query builder.</param> /// <param name="arguments">The paging arguments.</param> /// <param name="totalCount">Specify the total amount of elements</param> /// <param name="cancellationToken">The cancellation token.</param> /// <returns> /// Returns the connection. /// </returns> public async ValueTask <Connection <TEntity> > ApplyPaginationAsync( TQuery query, CursorPagingArguments arguments, int?totalCount, CancellationToken cancellationToken) { if (query is null) { throw new ArgumentNullException(nameof(query)); } var maxElementCount = int.MaxValue; Func <CancellationToken, ValueTask <int> > executeCount = totalCount is null ? ct => CountAsync(query, ct) : _ => new ValueTask <int>(totalCount.Value); // We only need the maximal element count if no `before` counter is set and no `first` // argument is provided. if (arguments.Before is null && arguments.First is null) { var count = await executeCount(cancellationToken); maxElementCount = count; // in case we already know the total count, we override the countAsync parameter // so that we do not have to fetch the count twice executeCount = _ => new ValueTask <int>(count); } CursorPagingRange range = SliceRange(arguments, maxElementCount); var skip = range.Start; var take = range.Count(); // we fetch one element more than we requested if (take != maxElementCount) { take++; } TQuery slicedSource = query; if (skip != 0) { slicedSource = ApplySkip(query, skip); } if (take != maxElementCount) { slicedSource = ApplyTake(slicedSource, take); } IReadOnlyList <Edge <TEntity> > selectedEdges = await ExecuteAsync(slicedSource, skip, cancellationToken); var moreItemsReturnedThanRequested = selectedEdges.Count > range.Count(); var isSequenceFromStart = range.Start == 0; selectedEdges = new SkipLastCollection <Edge <TEntity> >( selectedEdges, moreItemsReturnedThanRequested); ConnectionPageInfo pageInfo = CreatePageInfo(isSequenceFromStart, moreItemsReturnedThanRequested, selectedEdges); return(new Connection <TEntity>(selectedEdges, pageInfo, executeCount)); }