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Merged
merged 2 commits into from
Sep 28, 2020
Merged

Best effort paging #840

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c4c9908
Adds support for best-effort paging links (in case the total number o…
Sep 25, 2020
22d1843
Migrated PaginationLinkTests
Sep 25, 2020
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6 changes: 6 additions & 0 deletions src/JsonApiDotNetCore/Queries/IPaginationContext.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,12 @@ public interface IPaginationContext
/// </summary>
PageSize PageSize { get; set; }

/// <summary>
/// Indicates whether the number of resources on the current page equals the page size.
/// When <c>true</c>, a subsequent page might exist (assuming <see cref="TotalResourceCount"/> is unknown).
/// </summary>
bool IsPageFull { get; set; }

/// <summary>
/// The total number of resources.
/// <c>null</c> when <see cref="IJsonApiOptions.IncludeTotalResourceCount"/> is set to <c>false</c>.
Expand Down
3 changes: 3 additions & 0 deletions src/JsonApiDotNetCore/Queries/PaginationContext.cs
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Expand Up @@ -12,6 +12,9 @@ internal sealed class PaginationContext : IPaginationContext
/// <inheritdoc />
public PageSize PageSize { get; set; }

/// <inheritdoc />
public bool IsPageFull { get; set; }

/// <inheritdoc />
public int? TotalResourceCount { get; set; }

Expand Down
8 changes: 5 additions & 3 deletions src/JsonApiDotNetCore/QueryStrings/Internal/ResourceDefinitionQueryableParameterReader.cs
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Expand Up @@ -46,15 +46,17 @@ public virtual void Read(string parameterName, StringValues parameterValue)

private object GetQueryableHandler(string parameterName)
{
if (_request.Kind != EndpointKind.Primary)
var resourceType = _request.PrimaryResource.ResourceType;
var handler = _resourceDefinitionAccessor.GetQueryableHandlerForQueryStringParameter(resourceType, parameterName);

if (handler != null && _request.Kind != EndpointKind.Primary)
{
throw new InvalidQueryStringParameterException(parameterName,
"Custom query string parameters cannot be used on nested resource endpoints.",
$"Query string parameter '{parameterName}' cannot be used on a nested resource endpoint.");
}

var resourceType = _request.PrimaryResource.ResourceType;
return _resourceDefinitionAccessor.GetQueryableHandlerForQueryStringParameter(resourceType, parameterName);
return handler;
}

/// <inheritdoc />
Expand Down
120 changes: 90 additions & 30 deletions src/JsonApiDotNetCore/Serialization/Building/LinkBuilder.cs
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Expand Up @@ -5,6 +5,8 @@
using JsonApiDotNetCore.Configuration;
using JsonApiDotNetCore.Middleware;
using JsonApiDotNetCore.Queries;
using JsonApiDotNetCore.Queries.Expressions;
using JsonApiDotNetCore.Queries.Internal.Parsing;
using JsonApiDotNetCore.QueryStrings;
using JsonApiDotNetCore.Resources;
using JsonApiDotNetCore.Resources.Annotations;
Expand All @@ -15,6 +17,9 @@ namespace JsonApiDotNetCore.Serialization.Building
{
public class LinkBuilder : ILinkBuilder
{
private const string _pageSizeParameterName = "page[size]";
private const string _pageNumberParameterName = "page[number]";

private readonly IResourceContextProvider _provider;
private readonly IRequestQueryStringAccessor _queryStringAccessor;
private readonly IJsonApiOptions _options;
Expand Down Expand Up @@ -42,10 +47,10 @@ public TopLevelLinks GetTopLevelLinks()
TopLevelLinks topLevelLinks = null;
if (ShouldAddTopLevelLink(resourceContext, LinkTypes.Self))
{
topLevelLinks = new TopLevelLinks { Self = GetSelfTopLevelLink(resourceContext) };
topLevelLinks = new TopLevelLinks {Self = GetSelfTopLevelLink(resourceContext, null)};
}

if (ShouldAddTopLevelLink(resourceContext, LinkTypes.Paging) && _paginationContext.PageSize != null)
if (ShouldAddTopLevelLink(resourceContext, LinkTypes.Paging) && _paginationContext.PageSize != null && _request.IsCollection)
{
SetPageLinks(resourceContext, topLevelLinks ??= new TopLevelLinks());
}
Expand All @@ -70,36 +75,38 @@ private bool ShouldAddTopLevelLink(ResourceContext resourceContext, LinkTypes li

private void SetPageLinks(ResourceContext resourceContext, TopLevelLinks links)
{
if (_paginationContext.PageNumber.OneBasedValue > 1)
links.First = GetPageLink(resourceContext, 1, _paginationContext.PageSize);

if (_paginationContext.TotalPageCount > 0)
{
links.Prev = GetPageLink(resourceContext, _paginationContext.PageNumber.OneBasedValue - 1, _paginationContext.PageSize);
links.Last = GetPageLink(resourceContext, _paginationContext.TotalPageCount.Value, _paginationContext.PageSize);
}

if (_paginationContext.PageNumber.OneBasedValue < _paginationContext.TotalPageCount)
if (_paginationContext.PageNumber.OneBasedValue > 1)
{
links.Next = GetPageLink(resourceContext, _paginationContext.PageNumber.OneBasedValue + 1, _paginationContext.PageSize);
links.Prev = GetPageLink(resourceContext, _paginationContext.PageNumber.OneBasedValue - 1, _paginationContext.PageSize);
}

if (_paginationContext.TotalPageCount > 0)
bool hasNextPage = _paginationContext.PageNumber.OneBasedValue < _paginationContext.TotalPageCount;
bool possiblyHasNextPage = _paginationContext.TotalPageCount == null && _paginationContext.IsPageFull;

if (hasNextPage || possiblyHasNextPage)
{
links.Self = GetPageLink(resourceContext, _paginationContext.PageNumber.OneBasedValue, _paginationContext.PageSize);
links.First = GetPageLink(resourceContext, 1, _paginationContext.PageSize);
links.Last = GetPageLink(resourceContext, _paginationContext.TotalPageCount.Value, _paginationContext.PageSize);
links.Next = GetPageLink(resourceContext, _paginationContext.PageNumber.OneBasedValue + 1, _paginationContext.PageSize);
}
}

private string GetSelfTopLevelLink(ResourceContext resourceContext)
private string GetSelfTopLevelLink(ResourceContext resourceContext, Action<Dictionary<string, string>> queryStringUpdateAction)
{
var builder = new StringBuilder();
builder.Append(_request.BasePath);
builder.Append("/");
builder.Append(resourceContext.PublicName);

string resourceId = _request.PrimaryId;
if (resourceId != null)
if (_request.PrimaryId != null)
{
builder.Append("/");
builder.Append(resourceId);
builder.Append(_request.PrimaryId);
}

if (_request.Relationship != null)
Expand All @@ -108,49 +115,102 @@ private string GetSelfTopLevelLink(ResourceContext resourceContext)
builder.Append(_request.Relationship.PublicName);
}

builder.Append(DecodeSpecialCharacters(_queryStringAccessor.QueryString.Value));
string queryString = BuildQueryString(queryStringUpdateAction);
builder.Append(queryString);

return builder.ToString();
}

private string BuildQueryString(Action<Dictionary<string, string>> updateAction)
{
var parameters = _queryStringAccessor.Query.ToDictionary(pair => pair.Key, pair => pair.Value.ToString());
updateAction?.Invoke(parameters);
string queryString = QueryString.Create(parameters).Value;

return DecodeSpecialCharacters(queryString);
}

private static string DecodeSpecialCharacters(string uri)
{
return uri.Replace("%5B", "[").Replace("%5D", "]").Replace("%27", "'").Replace("%3A", ":");
}

private string GetPageLink(ResourceContext resourceContext, int pageOffset, PageSize pageSize)
{
string queryString = BuildQueryString(parameters =>
return GetSelfTopLevelLink(resourceContext, parameters =>
{
if (pageSize == null || pageSize.Equals(_options.DefaultPageSize))
var existingPageSizeParameterValue = parameters.ContainsKey(_pageSizeParameterName)
? parameters[_pageSizeParameterName]
: null;

PageSize newTopPageSize = Equals(pageSize, _options.DefaultPageSize) ? null : pageSize;

string newPageSizeParameterValue = ChangeTopPageSize(existingPageSizeParameterValue, newTopPageSize);
if (newPageSizeParameterValue == null)
{
parameters.Remove("page[size]");
parameters.Remove(_pageSizeParameterName);
}
else
{
parameters["page[size]"] = pageSize.ToString();
parameters[_pageSizeParameterName] = newPageSizeParameterValue;
}

if (pageOffset == 1)
{
parameters.Remove("page[number]");
parameters.Remove(_pageNumberParameterName);
}
else
{
parameters["page[number]"] = pageOffset.ToString();
parameters[_pageNumberParameterName] = pageOffset.ToString();
}
});

return $"{_request.BasePath}/{resourceContext.PublicName}" + queryString;
}

private string BuildQueryString(Action<Dictionary<string, string>> updateAction)
private string ChangeTopPageSize(string pageSizeParameterValue, PageSize topPageSize)
{
var parameters = _queryStringAccessor.Query.ToDictionary(pair => pair.Key, pair => pair.Value.ToString());
updateAction(parameters);
string queryString = QueryString.Create(parameters).Value;
var elements = ParsePageSizeExpression(pageSizeParameterValue);
var elementInTopScopeIndex = elements.FindIndex(expression => expression.Scope == null);

return DecodeSpecialCharacters(queryString);
if (topPageSize != null)
{
var topPageSizeElement = new PaginationElementQueryStringValueExpression(null, topPageSize.Value);

if (elementInTopScopeIndex != -1)
{
elements[elementInTopScopeIndex] = topPageSizeElement;
}
else
{
elements.Insert(0, topPageSizeElement);
}
}
else
{
if (elementInTopScopeIndex != -1)
{
elements.RemoveAt(elementInTopScopeIndex);
}
}

var parameterValue = string.Join(',',
elements.Select(expression => expression.Scope == null ? expression.Value.ToString() : $"{expression.Scope}:{expression.Value}"));

return parameterValue == string.Empty ? null : parameterValue;
}

private static string DecodeSpecialCharacters(string uri)
private List<PaginationElementQueryStringValueExpression> ParsePageSizeExpression(string pageSizeParameterValue)
{
return uri.Replace("%5B", "[").Replace("%5D", "]").Replace("%27", "'");
if (pageSizeParameterValue == null)
{
return new List<PaginationElementQueryStringValueExpression>();
}

var requestResource = _request.SecondaryResource ?? _request.PrimaryResource;

var parser = new PaginationParser(_provider);
var paginationExpression = parser.Parse(pageSizeParameterValue, requestResource);

return new List<PaginationElementQueryStringValueExpression>(paginationExpression.Elements);
}

/// <inheritdoc />
Expand Down
29 changes: 28 additions & 1 deletion src/JsonApiDotNetCore/Services/JsonApiResourceService.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
Expand Down Expand Up @@ -119,6 +120,11 @@ public virtual async Task<IReadOnlyCollection<TResource>> GetAsync()
{
var topFilter = _queryLayerComposer.GetTopFilter();
_paginationContext.TotalResourceCount = await _repository.CountAsync(topFilter);

if (_paginationContext.TotalResourceCount == 0)
{
return Array.Empty<TResource>();
}
}

var queryLayer = _queryLayerComposer.Compose(_request.PrimaryResource);
Expand All @@ -130,6 +136,11 @@ public virtual async Task<IReadOnlyCollection<TResource>> GetAsync()
return _hookExecutor.OnReturn(resources, ResourcePipeline.Get).ToArray();
}

if (queryLayer.Pagination?.PageSize != null && queryLayer.Pagination.PageSize.Value == resources.Count)
{
_paginationContext.IsPageFull = true;
}

return resources;
}

Expand Down Expand Up @@ -233,6 +244,14 @@ public virtual async Task<object> GetSecondaryAsync(TId id, string relationshipN
var secondaryLayer = _queryLayerComposer.Compose(_request.SecondaryResource);
var primaryLayer = _queryLayerComposer.WrapLayerForSecondaryEndpoint(secondaryLayer, _request.PrimaryResource, id, _request.Relationship);

if (_request.IsCollection && _options.IncludeTotalResourceCount)
{
// TODO: Consider support for pagination links on secondary resource collection. This requires to call Count() on the inverse relationship (which may not exist).
// For /blogs/1/articles we need to execute Count(Articles.Where(article => article.Blog.Id == 1 && article.Blog.existingFilter))) to determine TotalResourceCount.
// This also means we need to invoke ResourceRepository<Article>.CountAsync() from ResourceService<Blog>.
// And we should call BlogResourceDefinition.OnApplyFilter to filter out soft-deleted blogs and translate from equals('IsDeleted','false') to equals('Blog.IsDeleted','false')
}

var primaryResources = await _repository.GetAsync(primaryLayer);

var primaryResource = primaryResources.SingleOrDefault();
Expand All @@ -244,7 +263,15 @@ public virtual async Task<object> GetSecondaryAsync(TId id, string relationshipN
primaryResource = _hookExecutor.OnReturn(AsList(primaryResource), ResourcePipeline.GetRelationship).Single();
}

return _request.Relationship.GetValue(primaryResource);
var secondaryResource = _request.Relationship.GetValue(primaryResource);

if (secondaryResource is ICollection secondaryResources &&
secondaryLayer.Pagination?.PageSize != null && secondaryLayer.Pagination.PageSize.Value == secondaryResources.Count)
{
_paginationContext.IsPageFull = true;
}

return secondaryResource;
}

/// <inheritdoc />
Expand Down
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