Config inheritance array merge setting (#921)

config/vufind/config.ini

@@ -1135,6 +1135,12 @@ skip_numeric = true
 ; any sections not listed here will be merged on a section-by-section basis.
 ;override_full_sections = "Languages,AlphaBrowse_Types"
 
+; This setting is for allowing arrays to be merged with the values of their parents
+; arrays. If override_full_sections is set for a section the arrays will always be
+; overridden.
+; For legacy reasons merging of arrays is disabled by default.
+;merge_array_settings = false
+
 ; This section controls which language options are available to your users.
 ; If you offer more than one option, a control will appear in the user
 ; interface to allow user selection.  If you only activate one language,

module/VuFind/src/VuFind/Config/PluginFactory.php

@@ -113,6 +113,11 @@ class PluginFactory implements AbstractFactoryInterface
                 )
                 : [];
             foreach ($child as $section => $contents) {
+                // Check if arrays in the current config file should be merged with
+                // preceding arrays from config files defined as Parent_Config.
+                $mergeArraySettings
+                    = !empty($child->Parent_Config->merge_array_settings);
+
                 // Omit Parent_Config from the returned configuration; it is only
                 // needed during loading, and its presence will cause problems in
                 // config files that iterate through all of the sections (e.g.
@@ -126,7 +131,21 @@ class PluginFactory implements AbstractFactoryInterface
                     $config->$section = $child->$section;
                 } else {
                     foreach (array_keys($contents->toArray()) as $key) {
-                        $config->$section->$key = $child->$section->$key;
+                        // If a key is defined as key[] in the config file the key
+                        // remains a Zend\Config\Config object. If the current
+                        // section is not configured as an override section we try to
+                        // merge the key[] values instead of overwriting them.
+                        if (is_object($config->$section->$key)
+                            && is_object($child->$section->$key)
+                            && $mergeArraySettings
+                        ) {
+                            $config->$section->$key = array_merge(
+                                $config->$section->$key->toArray(),
+                                $child->$section->$key->toArray()
+                            );
+                        } else {
+                            $config->$section->$key = $child->$section->$key;
+                        }
                     }
                 }
             }

module/VuFind/tests/unit-tests/src/VuFindTest/Config/PluginFactoryTest.php

@@ -75,20 +75,36 @@ class PluginFactoryTest extends \VuFindTest\Unit\TestCase
             . "[Section2]\n"
             . "d=4\ne=5\nf=6\n"
             . "[Section3]\n"
-            . "g=7\nh=8\ni=9\n";
+            . "g=7\nh=8\ni=9\n"
+            . "[Section4]\n"
+            . "j[] = 1\nj[] = 2\nk[a] = 1\nk[b] = 2\n";
         $childPath = Locator::getLocalConfigPath('unit-test-child.ini', null, true);
         $child = "[Section1]\n"
             . "j=10\nk=11\nl=12\n"
             . "[Section2]\n"
             . "m=13\nn=14\no=15\n"
+            . "[Section4]\n"
+            . "j[] = 3\nk[c] = 3\n"
             . "[Parent_Config]\n"
             . "path=\"{$parentPath}\"\n"
             . "override_full_sections=Section1\n";
+        $child2Path = Locator::getLocalConfigPath('unit-test-child2.ini', null, true);
+        $child2 = "[Section1]\n"
+            . "j=10\nk=11\nl=12\n"
+            . "[Section2]\n"
+            . "m=13\nn=14\no=15\n"
+            . "[Section4]\n"
+            . "j[] = 3\nk[c] = 3\n"
+            . "[Parent_Config]\n"
+            . "path=\"{$parentPath}\"\n"
+            . "override_full_sections=Section1\n"
+            . "merge_array_settings=true\n";
 
         // Fail if we are unable to write files:
-        if (null === $parentPath || null === $childPath
+        if (null === $parentPath || null === $childPath || null === $child2Path
             || !file_put_contents($parentPath, $parent)
             || !file_put_contents($childPath, $child)
+            || !file_put_contents($child2Path, $child2)
         ) {
             self::$writeFailed = true;
             return;
@@ -175,6 +191,45 @@ class PluginFactoryTest extends \VuFindTest\Unit\TestCase
 
         // Make sure Section 3 was inherited; values from parent should exist.
         $this->assertEquals('7', $config->Section3->g);
+
+        // Make sure Section 4 arrays were overwritten.
+        $this->assertEquals([3], $config->Section4->j->toArray());
+        $this->assertEquals(['c' => 3], $config->Section4->k->toArray());
+    }
+
+    /**
+     * Test inheritance features with array merging turned on.
+     *
+     * @return void
+     */
+    public function testInheritanceWithArrayMerging()
+    {
+        if (self::$writeFailed) {
+            $this->markTestSkipped('Could not write test configurations.');
+        }
+
+        // Make sure load succeeds:
+        $config = $this->getConfig('unit-test-child2');
+        $this->assertTrue(is_object($config));
+
+        // Make sure Section 1 was overridden; values from parent should not be
+        // present.
+        $this->assertTrue(!isset($config->Section1->a));
+        $this->assertEquals('10', $config->Section1->j);
+
+        // Make sure Section 2 was merged; values from parent and child should
+        // both be present.
+        $this->assertEquals('4', $config->Section2->d);
+        $this->assertEquals('13', $config->Section2->m);
+
+        // Make sure Section 3 was inherited; values from parent should exist.
+        $this->assertEquals('7', $config->Section3->g);
+
+        // Make sure Section 4 arrays were overwritten.
+        $this->assertEquals([1, 2, 3], $config->Section4->j->toArray());
+        $this->assertEquals(
+            ['a' => 1, 'b' => 2, 'c' => 3], $config->Section4->k->toArray()
+        );
     }
 
     /**