API Filtering on invalid relation is no longer a silent error

Fixes #5331

model/DataList.php

@@ -503,7 +503,7 @@ class DataList extends ViewableData implements SS_List, SS_Filterable, SS_Sortab
 				$fieldName = array_pop($relations);
 
 				// Apply
-				$relationModelName = $query->applyRelation($field, $linearOnly);
+				$relationModelName = $query->applyRelation($relations, $linearOnly);
 
 				// Find the db field the relation belongs to
 				$className = ClassInfo::table_for_object_field($relationModelName, $fieldName);

model/DataQuery.php

@@ -641,16 +641,20 @@ class DataQuery {
 	 * mappings to the query object state. This has to be called
 	 * in any overloaded {@link SearchFilter->apply()} methods manually.
 	 *
-	 * @param String|array $relation The array/dot-syntax relation to follow
+	 * @param string|array $relation The array/dot-syntax relation to follow
 	 * @param bool $linearOnly Set to true to restrict to linear relations only. Set this
 	 * if this relation will be used for sorting, and should not include duplicate rows.
-	 * @return The model class of the related item
+	 * @return string The model class of the related item
 	 */
 	public function applyRelation($relation, $linearOnly = false) {
 		// NO-OP
-		if(!$relation) return $this->dataClass;
+		if(!$relation) {
+			return $this->dataClass;
+		}
 
-		if(is_string($relation)) $relation = explode(".", $relation);
+		if(is_string($relation)) {
+			$relation = explode(".", $relation);
+		}
 
 		$modelClass = $this->dataClass;
 
@@ -682,6 +686,8 @@ class DataQuery {
 				);
 				$modelClass = $componentClass;
 
+			} else {
+				throw new InvalidArgumentException("$rel is not a relation on model $modelClass");
 			}
 		}
 

tests/model/DataListTest.php

@@ -833,6 +833,17 @@ class DataListTest extends SapphireTest {
 		$this->assertEquals('007', $list->first()->ShirtNumber);
 	}
 
+	public function testFilterOnInvalidRelation() {
+		$this->setExpectedException(
+			'InvalidArgumentException',
+			"MascotAnimal is not a relation on model DataObjectTest_Team"
+		);
+		// Filter on missing relation 'MascotAnimal'
+		DataObjectTest_Team::get()
+			->filter('MascotAnimal.Name', 'Richard')
+			->toArray();
+	}
+
 	public function testFilterAndExcludeById() {
 		$id = $this->idFromFixture('DataObjectTest_SubTeam', 'subteam1');
 		$list = DataObjectTest_SubTeam::get()->filter('ID', $id);