Issue #1837018 by yched: Fixed Possible 'ambiguous column name' error in field_read_fields().

core/modules/field/field.crud.inc

@@ -354,6 +354,9 @@ function field_read_fields($params = array(), $include_additional = array()) {
       }
       $key = 'fci.' . $key;
     }
+    else {
+      $key = 'fc.' . $key;
+    }
 
     $query->condition($key, $value);
   }

core/modules/field/lib/Drupal/field/Tests/CrudTest.php

@@ -178,7 +178,7 @@ function testCreateFieldFail() {
   }
 
   /**
-   * Test reading back a field definition.
+   * Tests reading a single field definition.
    */
   function testReadField() {
     $field_definition = array(
@@ -192,6 +192,41 @@ function testReadField() {
     $this->assertTrue($field_definition < $field, 'The field was properly read.');
   }
 
+  /**
+   * Tests reading field definitions.
+   */
+  function testReadFields() {
+    $field_definition = array(
+      'field_name' => 'field_1',
+      'type' => 'test_field',
+    );
+    field_create_field($field_definition);
+
+    // Check that 'single column' criteria works.
+    $fields = field_read_fields(array('field_name' => $field_definition['field_name']));
+    $this->assertTrue(count($fields) == 1 && isset($fields[$field_definition['field_name']]), 'The field was properly read.');
+
+    // Check that 'multi column' criteria works.
+    $fields = field_read_fields(array('field_name' => $field_definition['field_name'], 'type' => $field_definition['type']));
+    $this->assertTrue(count($fields) == 1 && isset($fields[$field_definition['field_name']]), 'The field was properly read.');
+    $fields = field_read_fields(array('field_name' => $field_definition['field_name'], 'type' => 'foo'));
+    $this->assertTrue(empty($fields), 'No field was found.');
+
+    // Create an instance of the field.
+    $instance_definition = array(
+      'field_name' => $field_definition['field_name'],
+      'entity_type' => 'test_entity',
+      'bundle' => 'test_bundle',
+    );
+    field_create_instance($instance_definition);
+
+    // Check that criteria spanning over the field_config_instance table work.
+    $fields = field_read_fields(array('entity_type' => $instance_definition['entity_type'], 'bundle' => $instance_definition['bundle']));
+    $this->assertTrue(count($fields) == 1 && isset($fields[$field_definition['field_name']]), 'The field was properly read.');
+    $fields = field_read_fields(array('entity_type' => $instance_definition['entity_type'], 'field_name' => $instance_definition['field_name']));
+    $this->assertTrue(count($fields) == 1 && isset($fields[$field_definition['field_name']]), 'The field was properly read.');
+  }
+
   /**
    * Test creation of indexes on data column.
    */