Use different default mm for edismax vs. dismax.

- Resolves problem with edismax OR searches failing; thanks to Greg Pendlebury for input.
- See VUFIND-935 for more history.

module/VuFindSearch/src/VuFindSearch/Backend/Solr/SearchHandler.php

@@ -88,6 +88,8 @@ class SearchHandler
         if (empty($this->specs['DismaxHandler'])) {
             $this->specs['DismaxHandler'] = $defaultDismaxHandler;
         }
+        // Set default mm handler if necessary:
+        $this->setDefaultMustMatch();
     }
 
     /// Public API
@@ -248,6 +250,44 @@ class SearchHandler
 
     /// Internal API
 
+    /**
+     * Support method for constructor: if no mm is provided, set a reasonable
+     * default based on the selected Dismax handler.
+     *
+     * @return void
+     */
+    protected function setDefaultMustMatch()
+    {
+        // Initialize parameter array if absent:
+        if (!isset($this->specs['DismaxParams'])) {
+            $this->specs['DismaxParams'] = [];
+        }
+        // Add mm if applicable:
+        if ($this->hasDismax()) {
+            // Our default mm depends on whether we're using dismax or edismax;
+            // for dismax, we want 100% matches, because we always want to
+            // simulate "AND" behavior by default (any "OR" searches will get
+            // rerouted to Lucene queries). For edismax, boolean operators are
+            // accounted for, and with an mm of 100%, OR searches will always
+            // fail. We can use 0% here, because the default q.op of AND will
+            // make AND searches work correctly even without a high mm value.
+            $default = $this->hasExtendedDismax() ? '0%' : '100%';
+
+            // Now if the configuration has no explicit mm value, let's push in
+            // our default:
+            $foundSetting = false;
+            foreach ($this->specs['DismaxParams'] as $current) {
+                if ($current[0] == 'mm') {
+                    $foundSetting = true;
+                    break;
+                }
+            }
+            if (!$foundSetting) {
+                $this->specs['DismaxParams'][] = ['mm', $default];
+            }
+        }
+    }
+
     /**
      * Return a Dismax subquery for specified search string.
      *

module/VuFindSearch/tests/unit-tests/src/VuFindTest/Backend/Solr/QueryBuilderTest.php

@@ -302,7 +302,7 @@ class QueryBuilderTest extends \VuFindTest\Unit\TestCase
 
         $response = $qb->build($q);
         $processedQ = $response->get('q');
-        $this->assertEquals('((_query_:"{!dismax qf=\"field_a\" }value1") OR (_query_:"{!dismax qf=\"field_b\" }value2"))', $processedQ[0]);
+        $this->assertEquals('((_query_:"{!dismax qf=\"field_a\" mm=\\\'100%\\\'}value1") OR (_query_:"{!dismax qf=\"field_b\" mm=\\\'100%\\\'}value2"))', $processedQ[0]);
     }
 
     /**
@@ -333,7 +333,7 @@ class QueryBuilderTest extends \VuFindTest\Unit\TestCase
 
         $response = $qb->build($q);
         $processedQ = $response->get('q');
-        $this->assertEquals('((field_a:(value*)^100 OR field_c:(value*)^200) OR (_query_:"{!dismax qf=\"field_b\" }value2"))', $processedQ[0]);
+        $this->assertEquals('((field_a:(value*)^100 OR field_c:(value*)^200) OR (_query_:"{!dismax qf=\"field_b\" mm=\\\'100%\\\'}value2"))', $processedQ[0]);
     }
 
     /**

module/VuFindSearch/tests/unit-tests/src/VuFindTest/Backend/Solr/SearchHandlerTest.php

@@ -51,7 +51,7 @@ class SearchHandlerTest extends PHPUnit_Framework_TestCase
     {
         $spec = ['DismaxParams' => [['foo', 'bar']], 'DismaxFields' => ['field1', 'field2']];
         $hndl = new SearchHandler($spec);
-        $this->assertEquals('(_query_:"{!dismax qf=\"field1 field2\" foo=\\\'bar\\\'}foobar")', $hndl->createSimpleQueryString('foobar'));
+        $this->assertEquals('(_query_:"{!dismax qf=\"field1 field2\" foo=\\\'bar\\\' mm=\\\'100%\\\'}foobar")', $hndl->createSimpleQueryString('foobar'));
     }
 
     /**
@@ -72,7 +72,7 @@ class SearchHandlerTest extends PHPUnit_Framework_TestCase
      */
     public function testToArray()
     {
-        $spec = ['DismaxParams' => [['foo', 'bar']], 'DismaxFields' => ['field1', 'field2']];
+        $spec = ['DismaxParams' => [['foo', 'bar'], ['mm', '100%']], 'DismaxFields' => ['field1', 'field2']];
         $hndl = new SearchHandler($spec);
         $defaults = ['CustomMunge' => [], 'DismaxHandler' => 'dismax', 'QueryFields' => [], 'FilterQuery' => []];
         $this->assertEquals($spec + $defaults, $hndl->toArray());
@@ -87,7 +87,7 @@ class SearchHandlerTest extends PHPUnit_Framework_TestCase
     {
         $spec = ['DismaxParams' => [['foo', 'bar']], 'DismaxFields' => ['field1', 'field2']];
         $hndl = new SearchHandler($spec, 'edismax');
-        $this->assertEquals('(_query_:"{!edismax qf=\"field1 field2\" foo=\\\'bar\\\'}foobar")', $hndl->createSimpleQueryString('foobar'));
+        $this->assertEquals('(_query_:"{!edismax qf=\"field1 field2\" foo=\\\'bar\\\' mm=\\\'0%\\\'}foobar")', $hndl->createSimpleQueryString('foobar'));
     }
 
     /**