Treat RichText strings as JSON only when they parse to an object

telebot/types.py

@@ -14688,16 +14688,17 @@ def de_json(cls, json_string):
         if json_string is None: return None
         if isinstance(json_string, str):
             # "...can be either a String for plain text..."
-            if (json_string.startswith('{') and json_string.endswith('}')) or (json_string.startswith('[') and json_string.endswith(']')):
-                try:
-                    # Check if string is valid json. If so, assume it's json, not plain string
-                    json.loads(json_string)
-                    # If it's valid json, continue to json processing below
-                except (ValueError, TypeError, json.JSONDecodeError):
-                    # If it's not valid json, return the string as is
-                    return json_string
-            else:
+            # Only a JSON object is a serialized RichText. Plain text can look
+            # like JSON too, e.g. a "[56]" footnote mark, and stays text.
+            if not (json_string.startswith('{') and json_string.endswith('}')):
+                return json_string
+            try:
+                parsed = json.loads(json_string)
+            except (ValueError, TypeError):
+                return json_string
+            if not isinstance(parsed, dict):
                 return json_string
+            json_string = parsed
         elif isinstance(json_string, list):
             # "...an Array of :class:`RichText`..."
             return [RichText.de_json(item) for item in json_string]

tests/test_types.py

@@ -547,6 +547,17 @@ def test_json_richtextbold():
     assert result.text == 'Test'
 
 
+def test_json_richtext_plain_text_that_looks_like_json():
+    # issue #2634: a "[56]" footnote mark is plain text, not a JSON array
+    json_str = r'{"type": "url", "text": {"type": "superscript", "text": "[56]"}, "url": "https://example.com/#cite_note-56"}'
+    result = types.RichText.de_json(json_str)
+    assert isinstance(result, types.RichTextUrl)
+    assert isinstance(result.text, types.RichTextSuperscript)
+    assert result.text.text == '[56]'
+    for text in ['[56]', '[]', '{}x', '123', 'null', '["a", "b"]']:
+        assert types.RichText.de_json(text) == text
+
+
 def test_json_richtextitalic():
     json_str = r'{"type": "italic", "text": "Test"}'
     result = types.RichText.de_json(json_str)