From b39960f330d5f17e377d51ef2c80db9c80424f90 Mon Sep 17 00:00:00 2001
From: Vincent Gao <gaobing1230@gmail.com>
Date: Sat, 20 Jun 2026 20:18:32 +0200
Subject: [PATCH] Return false for contains(string, non-string) instead of
 raising

contains() with a string subject and a non-string search raised an
uncaught TypeError ("'in <string>' requires string as left operand")
instead of returning false. The JMESPath spec defines
contains('foobar', `123`) as false, and the array case already returns
false for a type-mismatched search of any type, so the string and array
paths were inconsistent.

Guard the membership test: when the subject is a string and the search
is not, return false (a non-string can never be a substring). Adds
compliance cases for number, boolean and null searches.
---
 jmespath/functions.py           |  8 ++++++++
 tests/compliance/functions.json | 12 ++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/jmespath/functions.py b/jmespath/functions.py
index 627b569d..e0164689 100644
--- a/jmespath/functions.py
+++ b/jmespath/functions.py
@@ -212,6 +212,14 @@ def _func_to_number(self, arg):
 
     @signature({'types': ['array', 'string']}, {'types': []})
     def _func_contains(self, subject, search):
+        # A non-string can never be a substring of a string. The array case
+        # already returns False for a non-matching search of any type, but
+        # ``search in subject`` raises TypeError when subject is a string and
+        # search is not, so guard it explicitly (spec: contains('foobar', 123)
+        # -> false).
+        if (isinstance(subject, STRING_TYPE)
+                and not isinstance(search, STRING_TYPE)):
+            return False
         return search in subject
 
     @signature({'types': ['string', 'array', 'object']})
diff --git a/tests/compliance/functions.json b/tests/compliance/functions.json
index 7b554450..b1536f4f 100644
--- a/tests/compliance/functions.json
+++ b/tests/compliance/functions.json
@@ -115,6 +115,18 @@
       "expression": "contains('abc', 'd')",
       "result": false
     },
+    {
+      "expression": "contains('foobar', `123`)",
+      "result": false
+    },
+    {
+      "expression": "contains('foobar', `true`)",
+      "result": false
+    },
+    {
+      "expression": "contains('foobar', `null`)",
+      "result": false
+    },
     {
       "expression": "contains(`false`, 'd')",
       "error": "invalid-type"