Allow placeholders in OpenAPI endpoints #2938 (#2940)

Use regex matches when checking endpoints instead of exact matches.
`{varname}` becomes `.*`

Fixes #2938

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/langchain/langchain/agents/agent_toolkits/openapi/planner.py

@@ -291,13 +291,16 @@ def _create_api_controller_tool(
             "{method} {route}".format(method=method, route=route.split("?")[0])
             for method, route in matches
         ]
-        endpoint_docs_by_name = {name: docs for name, _, docs in api_spec.endpoints}
         docs_str = ""
         for endpoint_name in endpoint_names:
-            docs = endpoint_docs_by_name.get(endpoint_name)
-            if not docs:
+            found_match = False
+            for name, _, docs in api_spec.endpoints:
+                regex_name = re.compile(re.sub("\{.*?\}", ".*", name))
+                if regex_name.match(endpoint_name):
+                    found_match = True
+                    docs_str += f"== Docs for {endpoint_name} == \n{yaml.dump(docs)}\n"
+            if not found_match:
                 raise ValueError(f"{endpoint_name} endpoint does not exist.")
-            docs_str += f"== Docs for {endpoint_name} == \n{yaml.dump(docs)}\n"
 
         agent = _create_api_controller_agent(base_url, docs_str, requests_wrapper, llm)
         return agent.run(plan_str)