fix(query-set): support multiple filters

closes #12

Author: jaredcnance

src/JsonApiDotNetCore/Controllers/JsonApiController.cs

@@ -167,8 +167,9 @@ private IQueryable<T> ApplySortAndFilterQuery(IQueryable<T> entities)
             if(_jsonApiContext.QuerySet == null)
                 return entities;
 
-            if(query.Filter != null)
-                entities = _entities.Filter(entities, query.Filter);
+            if(query.Filters.Count > 0)
+                foreach(var filter in query.Filters)
+                    entities = _entities.Filter(entities, filter);
 
             if(query.SortParameters != null && query.SortParameters.Count > 0)
                 entities = _entities.Sort(entities, query.SortParameters);

src/JsonApiDotNetCore/Data/DefaultEntityRepository.cs

@@ -123,7 +123,7 @@ public virtual async Task<bool> DeleteAsync(TId id)
             return true;
         }
 
-        public IQueryable<TEntity> Include(IQueryable<TEntity> entities, string relationshipName)
+        public virtual IQueryable<TEntity> Include(IQueryable<TEntity> entities, string relationshipName)
         {
             var entity = _jsonApiContext.RequestEntity;
             if(entity.Relationships.Any(r => r.RelationshipName == relationshipName))
@@ -133,7 +133,7 @@ public IQueryable<TEntity> Include(IQueryable<TEntity> entities, string relation
                 $"{entity.EntityName} does not have a relationship named {relationshipName}");
         }
 
-        public async Task<IEnumerable<TEntity>> PageAsync(IQueryable<TEntity> entities, int pageSize, int pageNumber)
+        public virtual async Task<IEnumerable<TEntity>> PageAsync(IQueryable<TEntity> entities, int pageSize, int pageNumber)
         {
             if(pageSize > 0)
                 return await entities

src/JsonApiDotNetCore/Internal/Query/QuerySet.cs

@@ -17,10 +17,11 @@ public QuerySet(
         {
             _jsonApiContext = jsonApiContext;
             PageQuery = new PageQuery();
+            Filters = new List<FilterQuery>();
             BuildQuerySet(query);
         }
 
-        public FilterQuery Filter { get; set; }
+        public List<FilterQuery> Filters { get; set; }
         public PageQuery PageQuery { get; set; }
         public List<SortQuery> SortParameters { get; set; }
         public List<string> IncludedRelationships { get; set; }
@@ -31,7 +32,7 @@ private void BuildQuerySet(IQueryCollection query)
             {
                 if (pair.Key.StartsWith("filter"))
                 {
-                    Filter = ParseFilterQuery(pair.Key, pair.Value);
+                    Filters.Add(ParseFilterQuery(pair.Key, pair.Value));
                     continue;
                 }
 
@@ -60,7 +61,7 @@ private FilterQuery ParseFilterQuery(string key, string value)
             var attribute = GetAttribute(propertyName);
 
             if (attribute == null)
-                return null;
+                throw new JsonApiException("400", $"{propertyName} is not a valid property.");
 
             return new FilterQuery(attribute, value);
         }