Make Solr\Backend::terms() more generic (#888)

- It is now easier to override hard-coded assumptions, and an alternate parameter format (with ParamBag first) is supported.

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

@@ -235,20 +235,43 @@ class Backend extends AbstractBackend
      *
      * @return Terms
      */
-    public function terms($field, $start, $limit, ParamBag $params = null)
-    {
+    public function terms($field = null, $start = null, $limit = null,
+        ParamBag $params = null
+    ) {
+        // Support alternate syntax with ParamBag as first parameter:
+        if ($field instanceof ParamBag && $params === null) {
+            $params = $field;
+            $field = null;
+        }
+
+        // Create empty ParamBag if none provided:
         $params = $params ?: new ParamBag();
         $this->injectResponseWriter($params);
 
+        // Always enable terms:
         $params->set('terms', 'true');
-        $params->set('terms.fl', $field);
-        $params->set('terms.lower', $start);
-        $params->set('terms.limit', $limit);
-        $params->set('terms.lower.incl', 'false');
-        $params->set('terms.sort', 'index');
+
+        // Use parameters if provided:
+        if (null !== $field) {
+            $params->set('terms.fl', $field);
+        }
+        if (null !== $start) {
+            $params->set('terms.lower', $start);
+        }
+        if (null !== $limit) {
+            $params->set('terms.limit', $limit);
+        }
+
+        // Set defaults unless overridden:
+        if (!$params->hasParam('terms.lower.incl')) {
+            $params->set('terms.lower.incl', 'false');
+        }
+        if (!$params->hasParam('terms.sort')) {
+            $params->set('terms.sort', 'index');
+        }
 
         $response = $this->connector->terms($params);
-        $terms    = new Terms($this->deserialize($response));
+        $terms = new Terms($this->deserialize($response));
         return $terms;
     }
 

module/VuFindSearch/src/VuFindSearch/ParamBag.php

@@ -76,6 +76,18 @@ class ParamBag
         return isset($this->params[$name]) ? $this->params[$name] : null;
     }
 
+    /**
+     * Return true if the bag contains any value(s) for the specified parameter.
+     *
+     * @param string $name Parameter name
+     *
+     * @return bool
+     */
+    public function hasParam($name)
+    {
+        return isset($this->params[$name]);
+    }
+
     /**
      * Return true if the bag contains a parameter-value-pair.
      *

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

@@ -143,6 +143,29 @@ class BackendTest extends PHPUnit_Framework_TestCase
         $this->assertCount(10, $terms->getFieldTerms('author'));
     }
 
+    /**
+     * Test terms component (using ParamBag as first param).
+     *
+     * @return void
+     */
+    public function testTermsWithParamBagAsFirstParameter()
+    {
+        $resp = $this->loadResponse('terms');
+        $conn = $this->getConnectorMock(['query']);
+        $conn->expects($this->once())
+            ->method('query')
+            ->will($this->returnValue($resp->getBody()));
+        $back = new Backend($conn);
+        $back->setIdentifier('test');
+        $bag = new ParamBag();
+        $bag->set('terms.fl', 'author');
+        $bag->set('terms.lower', '');
+        $bag->set('terms.limit', '-1');
+        $terms = $back->terms($bag);
+        $this->assertTrue($terms->hasFieldTerms('author'));
+        $this->assertCount(10, $terms->getFieldTerms('author'));
+    }
+
     /**
      * Test handling of a bad JSON response.
      *

module/VuFindSearch/tests/unit-tests/src/VuFindTest/ParamBagTest.php

@@ -43,6 +43,33 @@ use PHPUnit_Framework_TestCase as TestCase;
  */
 class ParamBagTest extends TestCase
 {
+    /**
+     * Test "contains"
+     *
+     * @return void
+     */
+    public function testContains()
+    {
+        $bag = new ParamBag();
+        $bag->set('foo', 'bar');
+        $this->assertTrue($bag->contains('foo', 'bar'));
+        $this->assertFalse($bag->contains('bar', 'foo'));
+        $this->assertFalse($bag->contains('foo', 'baz'));
+    }
+
+    /**
+     * Test "hasParam"
+     *
+     * @return void
+     */
+    public function testHasParam()
+    {
+        $bag = new ParamBag();
+        $bag->set('foo', 'bar');
+        $this->assertTrue($bag->hasParam('foo'));
+        $this->assertFalse($bag->hasParam('bar'));
+    }
+
     /**
      * Test "remove"
      *