Issue #3131379 by daffie, Beakerboy, Lendude, alexpott: CONCAT_WS requires at least 3 arguments

(cherry picked from commit 5c72f9f0)

core/modules/views/src/Plugin/views/filter/Combine.php

@@ -76,17 +76,21 @@ public function query() {
       }
     }
     if ($fields) {
-      $count = count($fields);
-      $separated_fields = [];
-      foreach ($fields as $key => $field) {
-        $separated_fields[] = $field;
-        if ($key < $count - 1) {
-          $separated_fields[] = "' '";
-        }
+      // We do not use the CONCAT_WS operator when there is only a single field.
+      // Using the CONCAT_WS operator with a single field is not a problem for
+      // the by core supported databases. Only the MS SQL Server requires the
+      // CONCAT_WS operator to be used with at least three arguments.
+      if (count($fields) == 1) {
+        $expression = reset($fields);
+      }
+      else {
+        // Multiple fields are separated by 3 spaces so that so that search
+        // strings that contain spaces are still only matched to single field
+        // values and not to multi-field values that exist only because we do
+        // the concatenation/LIKE trick.
+        $expression = implode(", ' ', ", $fields);
+        $expression = "CONCAT_WS(' ', $expression)";
       }
-      $expression = implode(', ', $separated_fields);
-      $expression = "CONCAT_WS(' ', $expression)";
-
       $info = $this->operators();
       if (!empty($info[$this->operator]['method'])) {
         $this->{$info[$this->operator]['method']}($expression);

core/modules/views/tests/src/Kernel/Handler/FilterCombineTest.php

@@ -188,6 +188,10 @@ public function testFilterCombineAllWords() {
       ],
     ];
     $this->assertIdenticalResultset($view, $resultset, $this->columnMap);
+
+    // Confirm that the query with multiple filters used the "CONCAT_WS"
+    // operator.
+    $this->assertStringContainsString('CONCAT_WS(', $view->query->query());
   }
 
   /**
@@ -271,6 +275,10 @@ public function testNonFieldsRow() {
     $errors = $view->validate();
     // Check that the right error is shown.
     $this->assertEquals(t('%display: %filter can only be used on displays that use fields. Set the style or row format for that display to one using fields to use the combine field filter.', ['%filter' => 'Global: Combine fields filter', '%display' => 'Master']), reset($errors['default']));
+
+    // Confirm that the query with single filter does not use the "CONCAT_WS"
+    // operator.
+    $this->assertStringNotContainsString('CONCAT_WS(', $view->query->query());
   }
 
   /**