Feat/sparse field sets

README.md

@@ -28,6 +28,7 @@ JsonApiDotnetCore provides a framework for building [json:api](http://jsonapi.or
     - [Meta](#meta)
     - [Client Generated Ids](#client-generated-ids)
     - [Custom Errors](#custom-errors)
+    - [Sparse Fieldsets](#sparse-fieldsets)
 - [Tests](#tests)
 
 ## Comprehensive Demo
@@ -397,6 +398,23 @@ public override async Task<IActionResult> PostAsync([FromBody] MyEntity entity)
 }
 ```
 
+### Sparse Fieldsets
+
+We currently support top-level field selection. 
+What this means is you can restrict which fields are returned by a query using the `fields` query parameter, but this does not yet apply to included relationships.
+
+- Currently valid:
+```http
+GET /articles?fields[articles]=title,body HTTP/1.1
+Accept: application/vnd.api+json
+```
+
+- Not yet supported:
+```http
+GET /articles?include=author&fields[articles]=title,body&fields[people]=name HTTP/1.1
+Accept: application/vnd.api+json
+```
+
 ## Tests
 
 I am using DotNetCoreDocs to generate sample requests and documentation.

src/JsonApiDotNetCore/Builders/DocumentBuilder.cs

@@ -33,12 +33,12 @@ public Document Build(IIdentifiable entity)
 
             var document = new Document
             {
-                Data = _getData(contextEntity, entity),
-                Meta = _getMeta(entity),
+                Data = GetData(contextEntity, entity),
+                Meta = GetMeta(entity),
                 Links = _jsonApiContext.PageManager.GetPageLinks(new LinkBuilder(_jsonApiContext))
             };
 
-            document.Included = _appendIncludedObject(document.Included, contextEntity, entity);
+            document.Included = AppendIncludedObject(document.Included, contextEntity, entity);
 
             return document;
         }
@@ -54,20 +54,20 @@ public Documents Build(IEnumerable<IIdentifiable> entities)
             var documents = new Documents
             {
                 Data = new List<DocumentData>(),
-                Meta = _getMeta(entities.FirstOrDefault()),
+                Meta = GetMeta(entities.FirstOrDefault()),
                 Links = _jsonApiContext.PageManager.GetPageLinks(new LinkBuilder(_jsonApiContext))
             };
 
             foreach (var entity in entities)
             {
-                documents.Data.Add(_getData(contextEntity, entity));
-                documents.Included = _appendIncludedObject(documents.Included, contextEntity, entity);
+                documents.Data.Add(GetData(contextEntity, entity));
+                documents.Included = AppendIncludedObject(documents.Included, contextEntity, entity);
             }
 
             return documents;
         }
 
-        private Dictionary<string, object> _getMeta(IIdentifiable entity)
+        private Dictionary<string, object> GetMeta(IIdentifiable entity)
         {
             if (entity == null) return null;
 
@@ -87,9 +87,9 @@ private Dictionary<string, object> _getMeta(IIdentifiable entity)
             return null;
         }
 
-        private List<DocumentData> _appendIncludedObject(List<DocumentData> includedObject, ContextEntity contextEntity, IIdentifiable entity)
+        private List<DocumentData> AppendIncludedObject(List<DocumentData> includedObject, ContextEntity contextEntity, IIdentifiable entity)
         {
-            var includedEntities = _getIncludedEntities(contextEntity, entity);
+            var includedEntities = GetIncludedEntities(contextEntity, entity);
             if (includedEntities.Count > 0)
             {
                 if (includedObject == null)
@@ -100,7 +100,7 @@ private List<DocumentData> _appendIncludedObject(List<DocumentData> includedObje
             return includedObject;
         }
 
-        private DocumentData _getData(ContextEntity contextEntity, IIdentifiable entity)
+        private DocumentData GetData(ContextEntity contextEntity, IIdentifiable entity)
         {
             var data = new DocumentData
             {
@@ -115,16 +115,24 @@ private DocumentData _getData(ContextEntity contextEntity, IIdentifiable entity)
 
             contextEntity.Attributes.ForEach(attr =>
             {
-                data.Attributes.Add(attr.PublicAttributeName, attr.GetValue(entity));
+                if(ShouldIncludeAttribute(attr))
+                    data.Attributes.Add(attr.PublicAttributeName, attr.GetValue(entity));
             });
 
             if (contextEntity.Relationships.Count > 0)
-                _addRelationships(data, contextEntity, entity);
+                AddRelationships(data, contextEntity, entity);
 
             return data;
         }
 
-        private void _addRelationships(DocumentData data, ContextEntity contextEntity, IIdentifiable entity)
+        private bool ShouldIncludeAttribute(AttrAttribute attr)
+        {
+            return (_jsonApiContext.QuerySet == null 
+                || _jsonApiContext.QuerySet.Fields.Count == 0 
+                || _jsonApiContext.QuerySet.Fields.Contains(attr.InternalAttributeName));
+        }
+
+        private void AddRelationships(DocumentData data, ContextEntity contextEntity, IIdentifiable entity)
         {
             data.Relationships = new Dictionary<string, RelationshipData>();
             var linkBuilder = new LinkBuilder(_jsonApiContext);
@@ -140,57 +148,57 @@ private void _addRelationships(DocumentData data, ContextEntity contextEntity, I
                     }
                 };
 
-                if (_relationshipIsIncluded(r.InternalRelationshipName))
+                if (RelationshipIsIncluded(r.InternalRelationshipName))
                 {
                     var navigationEntity = _jsonApiContext.ContextGraph
                         .GetRelationship(entity, r.InternalRelationshipName);
 
                     if(navigationEntity == null)
                         relationshipData.SingleData = null;
                     else if (navigationEntity is IEnumerable)
-                        relationshipData.ManyData = _getRelationships((IEnumerable<object>)navigationEntity, r.InternalRelationshipName);
+                        relationshipData.ManyData = GetRelationships((IEnumerable<object>)navigationEntity, r.InternalRelationshipName);
                     else
-                        relationshipData.SingleData = _getRelationship(navigationEntity, r.InternalRelationshipName);
+                        relationshipData.SingleData = GetRelationship(navigationEntity, r.InternalRelationshipName);
                 }
 
                 data.Relationships.Add(r.InternalRelationshipName.Dasherize(), relationshipData);
             });
         }
 
-        private List<DocumentData> _getIncludedEntities(ContextEntity contextEntity, IIdentifiable entity)
+        private List<DocumentData> GetIncludedEntities(ContextEntity contextEntity, IIdentifiable entity)
         {
             var included = new List<DocumentData>();
 
             contextEntity.Relationships.ForEach(r =>
             {
-                if (!_relationshipIsIncluded(r.InternalRelationshipName)) return;
+                if (!RelationshipIsIncluded(r.InternalRelationshipName)) return;
 
                 var navigationEntity = _jsonApiContext.ContextGraph.GetRelationship(entity, r.InternalRelationshipName);
 
                 if (navigationEntity is IEnumerable)
                     foreach (var includedEntity in (IEnumerable)navigationEntity)
-                        _addIncludedEntity(included, (IIdentifiable)includedEntity);
+                        AddIncludedEntity(included, (IIdentifiable)includedEntity);
                 else
-                    _addIncludedEntity(included, (IIdentifiable)navigationEntity);
+                    AddIncludedEntity(included, (IIdentifiable)navigationEntity);
             });
 
             return included;
         }
 
-        private void _addIncludedEntity(List<DocumentData> entities, IIdentifiable entity)
+        private void AddIncludedEntity(List<DocumentData> entities, IIdentifiable entity)
         {
-            var includedEntity = _getIncludedEntity(entity);
+            var includedEntity = GetIncludedEntity(entity);
             if(includedEntity != null)
                 entities.Add(includedEntity);
         }
 
-        private DocumentData _getIncludedEntity(IIdentifiable entity)
+        private DocumentData GetIncludedEntity(IIdentifiable entity)
         {
             if(entity == null) return null;
 
             var contextEntity = _jsonApiContext.ContextGraph.GetContextEntity(entity.GetType());
 
-            var data = _getData(contextEntity, entity);
+            var data = GetData(contextEntity, entity);
 
             data.Attributes = new Dictionary<string, object>();
 
@@ -202,13 +210,13 @@ private DocumentData _getIncludedEntity(IIdentifiable entity)
             return data;
         }
 
-        private bool _relationshipIsIncluded(string relationshipName)
+        private bool RelationshipIsIncluded(string relationshipName)
         {
             return _jsonApiContext.IncludedRelationships != null &&
                 _jsonApiContext.IncludedRelationships.Contains(relationshipName.ToProperCase());
         }
 
-        private List<Dictionary<string, string>> _getRelationships(IEnumerable<object> entities, string relationshipName)
+        private List<Dictionary<string, string>> GetRelationships(IEnumerable<object> entities, string relationshipName)
         {
             var objType = entities.GetType().GenericTypeArguments[0];
 
@@ -224,7 +232,7 @@ private List<Dictionary<string, string>> _getRelationships(IEnumerable<object> e
             }
             return relationships;
         }
-        private Dictionary<string, string> _getRelationship(object entity, string relationshipName)
+        private Dictionary<string, string> GetRelationship(object entity, string relationshipName)
         {
             var objType = entity.GetType();
 

src/JsonApiDotNetCore/Data/DefaultEntityRepository.cs

@@ -48,7 +48,7 @@ public DefaultEntityRepository(
 
         public virtual IQueryable<TEntity> Get()
         {
-            return _dbSet;
+            return _dbSet.Select(_jsonApiContext.QuerySet?.Fields);
         }
 
         public virtual IQueryable<TEntity> Filter(IQueryable<TEntity> entities,  FilterQuery filterQuery)
@@ -76,12 +76,12 @@ public virtual IQueryable<TEntity> Sort(IQueryable<TEntity> entities, List<SortQ
 
         public virtual async Task<TEntity> GetAsync(TId id)
         {
-            return await _dbSet.SingleOrDefaultAsync(e => e.Id.Equals(id));
+            return await Get().SingleOrDefaultAsync(e => e.Id.Equals(id));
         }
 
         public virtual async Task<TEntity> GetAndIncludeAsync(TId id, string relationshipName)
         {
-            return await _dbSet
+            return await Get()
                 .Include(relationshipName)
                 .SingleOrDefaultAsync(e => e.Id.Equals(id));
         }

src/JsonApiDotNetCore/Extensions/IQueryableExtensions.cs

@@ -1,5 +1,5 @@
-
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
@@ -126,5 +126,30 @@ public static IQueryable<TSource> Filter<TSource>(this IQueryable<TSource> sourc
                 throw new JsonApiException("400", $"Could not cast {filterQuery.PropertyValue} to {property.PropertyType.Name}");
             }
         }
+        public static IQueryable<TSource> Select<TSource>(this IQueryable<TSource> source, IEnumerable<string> columns)
+        {
+            if(columns == null || columns.Count() == 0)
+                return source;
+
+            var sourceType = source.ElementType;
+
+            var resultType = typeof(TSource);
+
+            // {model}
+            var parameter = Expression.Parameter(sourceType, "model");
+
+            var bindings = columns.Select(column => Expression.Bind(
+                resultType.GetProperty(column), Expression.PropertyOrField(parameter, column)));
+
+            // { new Model () { Property = model.Property } }
+            var body = Expression.MemberInit(Expression.New(resultType), bindings);
+
+            // { model => new TodoItem() { Property = model.Property } }
+            var selector = Expression.Lambda(body, parameter);
+
+            return source.Provider.CreateQuery<TSource>(
+                Expression.Call(typeof(Queryable), "Select", new Type[] { sourceType, resultType },
+                source.Expression, Expression.Quote(selector)));
+        }
     }
 }

src/JsonApiDotNetCore/Internal/Query/QuerySet.cs

@@ -19,13 +19,15 @@ public QuerySet(
             _jsonApiContext = jsonApiContext;
             PageQuery = new PageQuery();
             Filters = new List<FilterQuery>();
+            Fields = new List<string>();
             BuildQuerySet(query);
         }
 
         public List<FilterQuery> Filters { get; set; }
         public PageQuery PageQuery { get; set; }
         public List<SortQuery> SortParameters { get; set; }
         public List<string> IncludedRelationships { get; set; }
+        public List<string> Fields { get; set; }
 
         private void BuildQuerySet(IQueryCollection query)
         {
@@ -55,6 +57,12 @@ private void BuildQuerySet(IQueryCollection query)
                     continue;
                 }
 
+                if (pair.Key.StartsWith("fields"))
+                {
+                    Fields = ParseFieldsQuery(pair.Key, pair.Value);
+                    continue;
+                }
+
                 throw new JsonApiException("400", $"{pair} is not a valid query.");
             }
         }
@@ -160,6 +168,29 @@ private List<string> ParseIncludedRelationships(string value)
                 .ToList();
         }
 
+        private List<string> ParseFieldsQuery(string key, string value)
+        {
+            // expected: fields[TYPE]=prop1,prop2
+            var typeName = key.Split('[', ']')[1];
+
+            var includedFields = new List<string> { "Id" };
+
+            if(typeName != _jsonApiContext.RequestEntity.EntityName.Dasherize()) 
+                return includedFields;
+
+            var fields = value.Split(',');
+            foreach(var field in fields)
+            {
+                var internalAttrName = _jsonApiContext.RequestEntity
+                    .Attributes
+                    .SingleOrDefault(attr => attr.PublicAttributeName == field)
+                    .InternalAttributeName;
+                includedFields.Add(internalAttrName);
+            }
+
+            return includedFields;
+        }
+
         private AttrAttribute GetAttribute(string propertyName)
         {
             return _jsonApiContext.RequestEntity.Attributes

test/JsonApiDotNetCoreExampleTests/Acceptance/Extensibility/CustomErrorTests.cs

@@ -1,11 +1,7 @@
-using DotNetCoreDocs;
-using JsonApiDotNetCoreExample;
-using DotNetCoreDocs.Writers;
 using Newtonsoft.Json;
 using JsonApiDotNetCore.Internal;
 using JsonApiDotNetCore.Serialization;
 using Xunit;
-using System.Diagnostics;
 
 namespace JsonApiDotNetCoreExampleTests.Acceptance.Extensibility
 {
@@ -14,8 +10,6 @@ public class CustomErrorTests
         [Fact]
         public void Can_Return_Custom_Error_Types()
         {
-            // while(!Debugger.IsAttached) { bool stop = false; }
-
             // arrange
             var error = new CustomError("507", "title", "detail", "custom");
             var errorCollection = new ErrorCollection();