Nested sort

src/Examples/JsonApiDotNetCoreExample/Models/Person.cs

@@ -19,6 +19,9 @@ public class Person : Identifiable, IHasMeta
         [Attr("last-name")]
         public string LastName { get; set; }
 
+        [Attr("age")]
+        public int Age { get; set; }
+
         [HasMany("todo-items")]
         public virtual List<TodoItem> TodoItems { get; set; }
 

src/JsonApiDotNetCore/Data/DefaultEntityRepository.cs

@@ -58,7 +58,7 @@ public DefaultEntityRepository(
         public virtual IQueryable<TEntity> Get()
         {
             if (_jsonApiContext.QuerySet?.Fields != null && _jsonApiContext.QuerySet.Fields.Count > 0)
-                return _dbSet.Select(_jsonApiContext.QuerySet?.Fields);
+                return _dbSet.Select(_jsonApiContext.QuerySet.Fields);
 
             return _dbSet;
         }
@@ -72,7 +72,7 @@ public virtual IQueryable<TEntity> Filter(IQueryable<TEntity> entities, FilterQu
         /// <inheritdoc />
         public virtual IQueryable<TEntity> Sort(IQueryable<TEntity> entities, List<SortQuery> sortQueries)
         {
-            return entities.Sort(sortQueries);
+            return entities.Sort(_jsonApiContext,sortQueries);
         }
 
         /// <inheritdoc />

src/JsonApiDotNetCore/Internal/Query/AttrFilterQuery.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Linq;
 using JsonApiDotNetCore.Models;
 using JsonApiDotNetCore.Services;
@@ -6,32 +7,25 @@ namespace JsonApiDotNetCore.Internal.Query
 {
     public class AttrFilterQuery : BaseFilterQuery
     {
-        private readonly IJsonApiContext _jsonApiContext;
-
         public AttrFilterQuery(
             IJsonApiContext jsonApiContext,
             FilterQuery filterQuery)
+            : base(jsonApiContext, 
+                  null,
+                  filterQuery.Attribute, 
+                  filterQuery.Value, 
+                  filterQuery.OperationType)
         {
-            _jsonApiContext = jsonApiContext;
-
-            var attribute = GetAttribute(filterQuery.Attribute);
-
-            if (attribute == null)
+            if (Attribute == null)
                 throw new JsonApiException(400, $"'{filterQuery.Attribute}' is not a valid attribute.");
 
-            if (attribute.IsFilterable == false)
-                throw new JsonApiException(400, $"Filter is not allowed for attribute '{attribute.PublicAttributeName}'.");
+            if (Attribute.IsFilterable == false)
+                throw new JsonApiException(400, $"Filter is not allowed for attribute '{Attribute.PublicAttributeName}'.");
 
-            FilteredAttribute = attribute;
-            PropertyValue = filterQuery.Value;
-            FilterOperation = GetFilterOperation(filterQuery.Operation);
+            FilteredAttribute = Attribute;
         }
 
-        public AttrAttribute FilteredAttribute { get; }
-        public string PropertyValue { get; }
-        public FilterOperations FilterOperation { get; }
-
-        private AttrAttribute GetAttribute(string attribute) =>
-            _jsonApiContext.RequestEntity.Attributes.FirstOrDefault(attr => attr.Is(attribute));
+        [Obsolete("Use " + nameof(Attribute) + " property of " + nameof(BaseAttrQuery) + "class. This property is shared for all AttrQuery and RelatedAttrQuery (filter,sort..) implementations.")]
+        public AttrAttribute FilteredAttribute { get; set; }
     }
 }

src/JsonApiDotNetCore/Internal/Query/AttrSortQuery.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Linq;
+using JsonApiDotNetCore.Models;
+using JsonApiDotNetCore.Services;
+
+namespace JsonApiDotNetCore.Internal.Query
+{
+    public class AttrSortQuery : BaseAttrQuery
+    {
+        public AttrSortQuery(
+            IJsonApiContext jsonApiContext,
+            SortQuery sortQuery)
+            :base(jsonApiContext, null, sortQuery.Attribute)
+        {
+            if (Attribute == null)
+                throw new JsonApiException(400, $"'{sortQuery.Attribute}' is not a valid attribute.");
+
+            if (Attribute.IsSortable == false)
+                throw new JsonApiException(400, $"Sort is not allowed for attribute '{Attribute.PublicAttributeName}'.");
+
+            Direction = sortQuery.Direction;
+        }
+
+        public SortDirection Direction { get; }
+    }
+}

src/JsonApiDotNetCore/Internal/Query/BaseAttrQuery.cs

@@ -0,0 +1,54 @@
+using JsonApiDotNetCore.Models;
+using JsonApiDotNetCore.Services;
+using System.Linq;
+
+namespace JsonApiDotNetCore.Internal.Query
+{
+    /// <summary>
+    /// Abstract class to make available shared properties of all query implementations
+    /// It elimines boilerplate of providing specified type(AttrQuery or RelatedAttrQuery) 
+    /// while filter and sort operations and eliminates plenty of methods to keep DRY principles 
+    /// </summary>
+    public abstract class BaseAttrQuery
+    {
+        private readonly IJsonApiContext _jsonApiContext;
+
+        public BaseAttrQuery(IJsonApiContext jsonApiContext, string relationship, string attribute)
+        {
+            _jsonApiContext = jsonApiContext;
+            if (string.IsNullOrEmpty(relationship))
+                Attribute = GetAttribute(attribute);           
+            else
+            {
+                Relationship = GetRelationship(relationship);
+                Attribute = GetAttribute(Relationship, attribute);
+            }
+
+        }
+
+        public AttrAttribute Attribute { get; }
+        public RelationshipAttribute Relationship { get; }
+        public bool IsAttributeOfRelationship => Relationship != null;
+
+        public string GetPropertyPath()
+        {
+            if (IsAttributeOfRelationship)
+                return string.Format("{0}.{1}", Relationship.InternalRelationshipName, Attribute.InternalAttributeName);
+            else
+                return Attribute.InternalAttributeName;
+        }
+
+        private AttrAttribute GetAttribute(string attribute)
+            => _jsonApiContext.RequestEntity.Attributes.FirstOrDefault(attr => attr.Is(attribute));
+
+        private RelationshipAttribute GetRelationship(string propertyName)
+            => _jsonApiContext.RequestEntity.Relationships.FirstOrDefault(r => r.Is(propertyName));
+
+        private AttrAttribute GetAttribute(RelationshipAttribute relationship, string attribute)
+        {
+            var relatedContextExntity = _jsonApiContext.ContextGraph.GetContextEntity(relationship.Type);
+            return relatedContextExntity.Attributes
+              .FirstOrDefault(a => a.Is(attribute));
+        }
+    }
+}

src/JsonApiDotNetCore/Internal/Query/BaseFilterQuery.cs

@@ -1,9 +1,24 @@
+using JsonApiDotNetCore.Models;
+using JsonApiDotNetCore.Services;
 using System;
 
 namespace JsonApiDotNetCore.Internal.Query
 {
-    public class BaseFilterQuery
+    public class BaseFilterQuery : BaseAttrQuery
     {
+        public BaseFilterQuery(
+            IJsonApiContext jsonApiContext,
+            string relationship,
+            string attribute,
+            string value,
+            FilterOperations op)
+        : base(jsonApiContext, relationship, attribute)
+        {
+            PropertyValue = value;
+            FilterOperation = op;
+        }
+
+        [Obsolete("To resolve operation use enum typed " + nameof(FilterQuery.OperationType) + " property of "+ nameof(FilterQuery) +" class")]
         protected FilterOperations GetFilterOperation(string prefix)
         {
             if (prefix.Length == 0) return FilterOperations.eq;
@@ -13,5 +28,8 @@ protected FilterOperations GetFilterOperation(string prefix)
 
             return opertion;
         }
+
+        public string PropertyValue { get; }
+        public FilterOperations FilterOperation { get; }
     }
 }

src/JsonApiDotNetCore/Internal/Query/BaseQuery.cs

@@ -0,0 +1,26 @@
+using JsonApiDotNetCore.Models;
+using JsonApiDotNetCore.Services;
+using System;
+using System.Linq;
+
+namespace JsonApiDotNetCore.Internal.Query
+{
+    public abstract class BaseQuery
+    {
+        public BaseQuery(string attribute)
+        {
+            var properties = attribute.Split(QueryConstants.DOT);
+            if(properties.Length > 1)
+            {
+                Relationship = properties[0];
+                Attribute = properties[1];
+            }
+            else
+                Attribute = properties[0];
+        }
+
+        public string Attribute { get; }
+        public string Relationship { get; }
+        public bool IsAttributeOfRelationship => Relationship != null;
+    }
+}

src/JsonApiDotNetCore/Internal/Query/FilterQuery.cs

@@ -1,23 +1,40 @@
 using System;
 using JsonApiDotNetCore.Extensions;
+using JsonApiDotNetCore.Models;
 
 namespace JsonApiDotNetCore.Internal.Query
 {
-    public class FilterQuery
+    public class FilterQuery : BaseQuery
     {
+        [Obsolete("Use constructor with FilterOperations operationType paremeter. Filter operation should be provided " +
+            "as enum type, not by string.")]
         public FilterQuery(string attribute, string value, string operation)
+            :base(attribute)
         {
-            Attribute = attribute;
-            Key = attribute.ToProperCase();
+            Key = attribute.ToProperCase();         
             Value = value;
             Operation = operation;
+
+            Enum.TryParse(operation, out FilterOperations opertion);
+            OperationType = opertion;
+        }
+
+        public FilterQuery(string attribute, string value, FilterOperations operationType)
+            : base(attribute)
+        {
+            Key = attribute.ToProperCase();
+            Value = value;
+            Operation = operationType.ToString();
+            OperationType = operationType;
         }
-        
+
         [Obsolete("Key has been replaced by '" + nameof(Attribute) + "'. Members should be located by their public name, not by coercing the provided value to the internal name.")]
         public string Key { get; set; }
-        public string Attribute { get; }
         public string Value { get; set; }
+        [Obsolete("Operation has been replaced by '" + nameof(OperationType) + "'. OperationType is typed enum value for Operation property. This should be default property for providing operation type, because of unsustainable string (not typed) value.")]
         public string Operation { get; set; }
-        public bool IsAttributeOfRelationship => Attribute.Contains(".");
+
+        public FilterOperations OperationType { get; set; }
+
     }
 }

src/JsonApiDotNetCore/Internal/Query/QueryConstants.cs

@@ -10,6 +10,7 @@ public static class QueryConstants {
         public const char COMMA = ',';
         public const char COLON = ':';
         public const string COLON_STR = ":";
+        public const char DOT = '.';
 
     }
-}
+}

src/JsonApiDotNetCore/Internal/Query/QuerySet.cs

@@ -10,4 +10,4 @@ public class QuerySet
         public List<string> IncludedRelationships { get; set; } = new List<string>();
         public List<string> Fields { get; set; } = new List<string>();
     }
-}
+}

src/JsonApiDotNetCore/Internal/Query/RelatedAttrFilterQuery.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Linq;
 using JsonApiDotNetCore.Models;
 using JsonApiDotNetCore.Services;
@@ -6,45 +7,28 @@ namespace JsonApiDotNetCore.Internal.Query
 {
     public class RelatedAttrFilterQuery : BaseFilterQuery
     {
-        private readonly IJsonApiContext _jsonApiContext;
-
         public RelatedAttrFilterQuery(
             IJsonApiContext jsonApiContext,
             FilterQuery filterQuery)
+            :base(jsonApiContext, filterQuery.Relationship, filterQuery.Attribute, filterQuery.Value, filterQuery.OperationType)
         {
-            _jsonApiContext = jsonApiContext;
+            if (Relationship == null)
+                throw new JsonApiException(400, $"{filterQuery.Relationship} is not a valid relationship on {jsonApiContext.RequestEntity.EntityName}.");
 
-            var relationshipArray = filterQuery.Attribute.Split('.');
-            var relationship = GetRelationship(relationshipArray[0]);
-            if (relationship == null)
-                throw new JsonApiException(400, $"{relationshipArray[1]} is not a valid relationship on {relationshipArray[0]}.");
-
-            var attribute = GetAttribute(relationship, relationshipArray[1]);
-            if (attribute == null)
+            if (Attribute == null)
                 throw new JsonApiException(400, $"'{filterQuery.Attribute}' is not a valid attribute.");
 
-            if (attribute.IsFilterable == false)
-                throw new JsonApiException(400, $"Filter is not allowed for attribute '{attribute.PublicAttributeName}'.");
+            if (Attribute.IsFilterable == false)
+                throw new JsonApiException(400, $"Filter is not allowed for attribute '{Attribute.PublicAttributeName}'.");
 
-            FilteredRelationship = relationship;
-            FilteredAttribute = attribute;
-            PropertyValue = filterQuery.Value;
-            FilterOperation = GetFilterOperation(filterQuery.Operation);
+            FilteredRelationship = Relationship;
+            FilteredAttribute = Attribute;
         }
 
+        [Obsolete("Use " + nameof(Attribute) + " property. It's shared for all implementations of BaseAttrQuery(better sort, filter) handling")]
         public AttrAttribute FilteredAttribute { get; set; }
-        public string PropertyValue { get; set; }
-        public FilterOperations FilterOperation { get; set; }
-        public RelationshipAttribute FilteredRelationship { get; }
-
-        private RelationshipAttribute GetRelationship(string propertyName)
-            => _jsonApiContext.RequestEntity.Relationships.FirstOrDefault(r => r.Is(propertyName));
 
-        private AttrAttribute GetAttribute(RelationshipAttribute relationship, string attribute)
-        {
-            var relatedContextExntity = _jsonApiContext.ContextGraph.GetContextEntity(relationship.Type);
-            return relatedContextExntity.Attributes
-              .FirstOrDefault(a => a.Is(attribute));
-        }
+        [Obsolete("Use " + nameof(Relationship) + " property. It's shared for all implementations of BaseAttrQuery(better sort, filter) handling")]
+        public RelationshipAttribute FilteredRelationship { get; set; }
     }
 }

src/JsonApiDotNetCore/Internal/Query/RelatedAttrSortQuery.cs

@@ -0,0 +1,29 @@
+using System;
+using System.Linq;
+using JsonApiDotNetCore.Models;
+using JsonApiDotNetCore.Services;
+
+namespace JsonApiDotNetCore.Internal.Query
+{
+    public class RelatedAttrSortQuery : BaseAttrQuery
+    {
+        public RelatedAttrSortQuery(
+            IJsonApiContext jsonApiContext,
+            SortQuery sortQuery)
+            :base(jsonApiContext, sortQuery.Relationship, sortQuery.Attribute)
+        {
+            if (Relationship == null)
+                throw new JsonApiException(400, $"{sortQuery.Relationship} is not a valid relationship on {jsonApiContext.RequestEntity.EntityName}.");
+
+            if (Attribute == null)
+                throw new JsonApiException(400, $"'{sortQuery.Attribute}' is not a valid attribute.");
+
+            if (Attribute.IsSortable == false)
+                throw new JsonApiException(400, $"Sort is not allowed for attribute '{Attribute.PublicAttributeName}'.");
+
+            Direction = sortQuery.Direction;
+        }
+
+        public SortDirection Direction { get; }
+    }
+}