[ODS-5174] Total count and paging is off when API Client is associate…

…d with Edorgs at multiple level (#392)

* Fix all problems related to duplicates in counts and paged data.

* Provided strongly-typed expression-based projection for the CountDistinct to avoid forcing a downstream conversions from string to int on final result processing.

* Fixed typo in variable name.

* Renamed GetKeyColumnProjections to GetCountColumnProjections and converted to local function for clarity of intent and scope of usage.

* Renamed method and added comments for better clarity.

* Change all usages of the total count from long to int.

Application/EdFi.Ods.Common/Infrastructure/Repositories/GetEntitiesBySpecification.cs

@@ -91,7 +91,7 @@ async Task<SpecificationResult> GetPagedAggregateIdsAsync()
                     var idQueryCriteria = _pagedAggregateIdsCriteriaProvider.GetCriteriaQuery(specification, queryParameters);
                     SetChangeQueriesCriteria(idQueryCriteria);
 
-                    queryBatch.Add<Guid>(idQueryCriteria);
+                    queryBatch.Add<object[]>(idQueryCriteria);
                 }
 
                 // If requested, get a total count of available records
@@ -100,17 +100,19 @@ async Task<SpecificationResult> GetPagedAggregateIdsAsync()
                     var countQueryCriteria = _totalCountCriteriaProvider.GetCriteriaQuery(specification, queryParameters);
                     SetChangeQueriesCriteria(countQueryCriteria);
 
-                    queryBatch.Add<long>(countQueryCriteria);
+                    queryBatch.Add<int>(countQueryCriteria);
                 }
 
                 int resultIndex = 0;
 
                 var ids = ItemsRequested()
-                    ? await queryBatch.GetResultAsync<Guid>(resultIndex++, cancellationToken)
-                    : new Guid[0];
+                    ? (await queryBatch.GetResultAsync<object[]>(resultIndex++, cancellationToken))
+                        .Select(r => (Guid) r[0])
+                        .ToArray()
+                    : Array.Empty<Guid>();
 
                 var totalCount = CountRequested()
-                    ? (await queryBatch.GetResultAsync<long>(resultIndex, cancellationToken)).First()
+                    ? (await queryBatch.GetResultAsync<int>(resultIndex, cancellationToken)).First()
                     : 0;
 
                 return new SpecificationResult
@@ -141,7 +143,7 @@ void SetChangeQueriesCriteria(ICriteria criteria)
         private class SpecificationResult
         {
             public IList<Guid> Ids { get; set; }
-            public long TotalCount { get; set; }
+            public int TotalCount { get; set; }
         }
     }
 }

Application/EdFi.Ods.Common/Providers/Criteria/PagedAggregateIdsCriteriaProvider.cs

@@ -3,6 +3,7 @@
 // The Ed-Fi Alliance licenses this file to you under the Apache License, Version 2.0.
 // See the LICENSE and NOTICES files in the project root for more information.
 
+using System;
 using EdFi.Ods.Common.Caching;
 using NHibernate;
 using NHibernate.Criterion;
@@ -18,8 +19,24 @@ public class PagedAggregateIdsCriteriaProvider<TEntity> : AggregateRootCriteriaP
         where TEntity : class
     {
         public PagedAggregateIdsCriteriaProvider(ISessionFactory sessionFactory, IDescriptorsCache descriptorsCache)
-            : base(sessionFactory, descriptorsCache) { }
+            : base(sessionFactory, descriptorsCache)
+        {
+            _identifierColumnNames = new Lazy<string[]>(
+                () =>
+                {
+                    var persister = (AbstractEntityPersister) SessionFactory.GetClassMetadata(typeof(TEntity));
+
+                    if (persister.IdentifierColumnNames != null && persister.IdentifierColumnNames.Length > 0)
+                    {
+                        return persister.IdentifierColumnNames;
+                    }
+
+                    return new[] { "Id" };
+                });
+        }
 
+        private readonly Lazy<string[]> _identifierColumnNames;
+
         /// <summary>
         /// Get a <see cref="NHibernate.ICriteria"/> query that retrieves the Ids for the next page of data.
         /// </summary>
@@ -29,7 +46,7 @@ public PagedAggregateIdsCriteriaProvider(ISessionFactory sessionFactory, IDescri
         public ICriteria GetCriteriaQuery(TEntity specification, IQueryParameters queryParameters)
         {
             var idQueryCriteria = Session.CreateCriteria<TEntity>("aggregateRoot")
-                .SetProjection(Projections.Property("Id"))
+                .SetProjection(Projections.Distinct(GetColumnProjectionsForDistinctWithOrderBy()))
                 .SetFirstResult(queryParameters.Offset ?? 0)
                 .SetMaxResults(queryParameters.Limit ?? 25);
 
@@ -42,22 +59,29 @@ public ICriteria GetCriteriaQuery(TEntity specification, IQueryParameters queryP
             ProcessQueryParameters(idQueryCriteria, queryParameters);
 
             return idQueryCriteria;
-        }
-
-        private void AddDefaultOrdering(ICriteria queryCriteria)
-        {
-            var persister = (AbstractEntityPersister) SessionFactory.GetClassMetadata(typeof(TEntity));
-
-            if (persister.IdentifierColumnNames != null && persister.IdentifierColumnNames.Length > 0)
+
+            IProjection GetColumnProjectionsForDistinctWithOrderBy()
             {
-                foreach (var identifierColumnName in persister.IdentifierColumnNames)
+                var projections = Projections.ProjectionList();
+
+                // Add the resource identifier (this is the value we need for the secondary "page" query)
+                projections.Add(Projections.Property("Id"));
+
+                // Add the order by (primary key) columns (required when using DISTINCT with ORDER BY)
+                foreach (var identifierColumnName in _identifierColumnNames.Value)
                 {
-                    queryCriteria.AddOrder(Order.Asc(identifierColumnName));
+                    projections.Add(Projections.Property(identifierColumnName));
                 }
+
+                return projections;
             }
-            else
+        }
+
+        private void AddDefaultOrdering(ICriteria queryCriteria)
+        {
+            foreach (var identifierColumnName in _identifierColumnNames.Value)
             {
-                queryCriteria.AddOrder(Order.Asc("Id"));
+                queryCriteria.AddOrder(Order.Asc(identifierColumnName));
             }
         }
     }

Application/EdFi.Ods.Common/Providers/Criteria/TotalCountCriteriaProvider.cs

@@ -4,6 +4,7 @@
 // See the LICENSE and NOTICES files in the project root for more information.
 
 using EdFi.Ods.Common.Caching;
+using EdFi.Ods.Common.Models.Domain;
 using NHibernate;
 using NHibernate.Criterion;
 
@@ -14,7 +15,7 @@ namespace EdFi.Ods.Common.Providers.Criteria
     /// </summary>
     /// <typeparam name="TEntity">The type of the entity to which criteria is being applied.</typeparam>
     public class TotalCountCriteriaProvider<TEntity> : AggregateRootCriteriaProviderBase<TEntity>, ITotalCountCriteriaProvider<TEntity>
-        where TEntity : class
+        where TEntity : AggregateRootWithCompositeKey
     {
         public TotalCountCriteriaProvider(ISessionFactory sessionFactory, IDescriptorsCache descriptorsCache)
             : base(sessionFactory, descriptorsCache) { }
@@ -29,7 +30,7 @@ public ICriteria GetCriteriaQuery(TEntity specification, IQueryParameters queryP
         {
             var countQueryCriteria = Session
                 .CreateCriteria<TEntity>("aggregateRoot")
-                .SetProjection(Projections.RowCountInt64());
+                .SetProjection(Projections.CountDistinct<TEntity>(x => x.Id));
 
             // Add specification-based criteria
             ProcessSpecification(countQueryCriteria, specification);

Application/EdFi.Ods.Common/Repositories/GetBySpecificationResult.cs

@@ -17,7 +17,7 @@ public class GetBySpecificationResult<TEntity>
 
     public class ResultMetadata
     {
-        public long TotalCount { get; set; }
+        public int TotalCount { get; set; }
 
         public string CurrentPage { get; set; }