ApiContentControllers::patch() double-encodes the 409 Conflict error message, producing malformed CLI output (#3588741) · Issues · project / canvas

ApiContentControllers::patch() double-encodes the 409 Conflict error message, producing malformed CLI output

>>> [!note] Migrated issue   Reported by: [mglaman](https://www.drupal.org/user/2416470) Related to !1067 >>> <h3 id="overview">Overview</h3> When <code>ApiContentControllers::patch()</code> detects an existing auto-save, it throws a <code>ConflictHttpException</code> with its message wrapped in <code>Json::encode()</code>. <code>ApiExceptionSubscriber</code> then serializes that string into the <code>errors</code> array of the JSON response, resulting in a double-encoded JSON string as the error value: <pre>{"errors": ["{"error":"Canvas Page with ID 42 has existing auto-saved data..."}"]}</pre>Canvas CLI's <code>parseCanvasErrors()</code> extracts <code>errors[0]</code> verbatim and surfaces it to the user, so the output is the raw JSON string rather than a readable message. Due to this, <a href="https://git.drupalcode.org/project/canvas/-/blob/1.x/packages/cli/src/services/api.ts?ref_type=heads#L697">https://git.drupalcode.org/project/canvas/-/blob/1.x/packages/cli/src/services/api.ts?ref_type=heads#L697</a> no errors were being returned. <h3 id="proposed-resolution">Proposed resolution</h3> Remove the <code>Json::encode()</code> wrapper in <code>ApiContentControllers::patch()</code> and pass a plain string to <code>ConflictHttpException</code>. <code>ApiExceptionSubscriber</code> serializes it once, producing a clean <code>errors[0]</code> value that <code>parseCanvasErrors()</code> surfaces correctly. Before: <pre><pre><?php throw new ConflictHttpException(Json::encode([   'error' => \sprintf('%s with ID %s has existing auto-saved data. Please use the UI to publish it or discard it.',     (string) $canvas_page->getEntityType()->getLabel(),     $canvas_page->id(),   ), ])); ?></pre></pre>After: <pre><pre><?php throw new ConflictHttpException(   \sprintf(     '%s with ID %s has existing auto-saved data. Please use the Canvas UI to publish or discard it before pushing.',     (string) $canvas_page->getEntityType()->getLabel(),     $canvas_page->id(),   ) ); ?></pre></pre><h3 id="ui-changes">User interface changes</h3> None in the Drupal UI. Canvas CLI output changes: a 409 response now produces a readable plain-text error message instead of a raw JSON string.

issue