Better handle null responses (returning acceptable "empty" response)

Still there is some case not covered (empty returns_desc and not null returns), but we aren't looking to them here.
moodlehq · Sep 20, 2023 · 641c3b6 · 641c3b6
1 parent 01b5784
commit 641c3b6
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diff --git a/CHANGES.md b/CHANGES.md
@@ -4,6 +4,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 The format of this change log follows the advice given at [Keep a CHANGELOG](http://keepachangelog.com).
 
 ## [Unreleased]
+### Fixed
+- Better behaviour when the external functions return null results, by providing and "acceptable" empty (xmlrpc-compliant) response.
 
 ## [1.0.3] - 2023-09-16
 ### Added

diff --git a/locallib.php b/locallib.php
@@ -121,15 +121,17 @@ protected function prepare_response() {
                     // TODO: Remove this branch condition once Moodle 4.1 is out of support.
                     $validatedvalues = external_api::clean_returnvalue($this->function->returns_desc, $this->returns);
                 }
-                $encodingoptions = [
-                    "encoding" => "UTF-8",
-                    "verbosity" => "no_white_space",
-                    // See MDL-54868.
-                    "escaping" => ["markup"]
-                ];
-                // We can now convert the response to the requested XML-RPC format.
-                $this->response = xmlrpc_encode_request(null, $validatedvalues, $encodingoptions);
+            } else if ($this->returns === null) {
+                $validatedvalues = $this->returns;
             }
+            $encodingoptions = [
+                "encoding" => "UTF-8",
+                "verbosity" => "no_white_space",
+                // See MDL-54868.
+                "escaping" => ["markup"],
+            ];
+            // We can now convert the response to the requested XML-RPC format.
+            $this->response = xmlrpc_encode_request(null, $validatedvalues, $encodingoptions);
         } catch (invalid_response_exception $ex) {
             $this->response = $this->generate_error($ex);
         }

diff --git a/tests/locallib_test.php b/tests/locallib_test.php
@@ -134,15 +134,20 @@ public function prepare_response_provider() {
                 'Ennyn Durin, Aran Moria: pedo mellon a minno',
                 'Mellon!',
                 '<?xml version="1.0" encoding="UTF-8"?><methodResponse><params><param><value><string>Mellon!</string></value>'
-                . '</param></params></methodResponse>'
+                . '</param></params></methodResponse>',
             ],
             'Description with non-Latin glyphs' => [
                 'What biscuits do you have?',
                 // V         Unicode 9!         V.
                 '😂🤵😂 𝒪𝓃𝓁𝓎 𝓉𝒽𝑒 𝒻𝒾𝓃𝑒𝓈𝓉 𝐼𝓉𝒶𝓁𝒾𝒶𝓃 𝒷𝒾𝓈𝒸𝓊𝒾𝓉𝓈 😂🤵😂',
                 '<?xml version="1.0" encoding="UTF-8"?><methodResponse><params><param><value><string>'
-                . '😂🤵😂 𝒪𝓃𝓁𝓎 𝓉𝒽𝑒 𝒻𝒾𝓃𝑒𝓈𝓉 𝐼𝓉𝒶𝓁𝒾𝒶𝓃 𝒷𝒾𝓈𝒸𝓊𝒾𝓉𝓈 😂🤵😂</string></value></param></params></methodResponse>'
-            ]
+                . '😂🤵😂 𝒪𝓃𝓁𝓎 𝓉𝒽𝑒 𝒻𝒾𝓃𝑒𝓈𝓉 𝐼𝓉𝒶𝓁𝒾𝒶𝓃 𝒷𝒾𝓈𝒸𝓊𝒾𝓉𝓈 😂🤵😂</string></value></param></params></methodResponse>',
+            ],
+            'Null returned data' => [
+                'Some desc is coming!',
+                null,
+               '<?xml version="1.0" encoding="UTF-8"?><methodResponse><params/></methodResponse>',
+            ],
         ];
     }