fix(client): skip pre-encoding for query params to prevent double url encoding

Author: Aryan Srivastava

langfuse/_client/client.py

@@ -3744,7 +3744,7 @@ def _url_encode(self, url: str, *, is_url_param: Optional[bool] = False) -> str:
         # “%”, “?”, “#”, “|”, … in query/path parts).  Re-quoting here would
         # double-encode, so we skip when the value is about to be sent straight
         # to httpx (`is_url_param=True`) and the installed version is ≥ 0.28.
-        if is_url_param and Version(httpx.__version__) >= Version("0.28.0"):
+        if is_url_param:
             return url
 
         # urllib.parse.quote does not escape slashes "/" by default; we need to add safe="" to force escaping

tests/unit/test_dataset_url_encoding.py

@@ -0,0 +1,94 @@
+import pytest
+from unittest.mock import patch, MagicMock
+from langfuse import Langfuse
+import httpx
+
+def test_dataset_url_encoding_in_requests():
+    with patch("httpx.Client.send") as mock_send:
+        # Mock response for get
+        mock_response = MagicMock(spec=httpx.Response)
+        mock_response.status_code = 200
+        mock_response.json.return_value = {
+            "id": "dataset-id",
+            "name": "my/dataset",
+            "description": "test",
+            "metadata": {},
+            "projectId": "project-id",
+            "createdAt": "2026-01-01T00:00:00Z",
+            "updatedAt": "2026-01-01T00:00:00Z"
+        }
+        mock_response.headers = httpx.Headers()
+
+        # Mock response for list
+        mock_items_response = MagicMock(spec=httpx.Response)
+        mock_items_response.status_code = 200
+        mock_items_response.json.return_value = {
+            "data": [],
+            "meta": {"page": 1, "limit": 50, "totalItems": 0, "totalPages": 1}
+        }
+
+        # Mock response for run
+        mock_run_response = MagicMock(spec=httpx.Response)
+        mock_run_response.status_code = 200
+        mock_run_response.json.return_value = {
+            "id": "run-id",
+            "name": "my/run",
+            "datasetName": "my/dataset",
+            "datasetId": "dataset-id",
+            "createdAt": "2026-01-01T00:00:00Z",
+            "updatedAt": "2026-01-01T00:00:00Z",
+            "metadata": {},
+            "datasetRunItems": []
+        }
+
+        # Mock response for runs
+        mock_runs_response = MagicMock(spec=httpx.Response)
+        mock_runs_response.status_code = 200
+        mock_runs_response.json.return_value = {
+            "data": [],
+            "meta": {"page": 1, "limit": 50, "totalItems": 0, "totalPages": 1}
+        }
+
+        # Mock response for delete
+        mock_delete_response = MagicMock(spec=httpx.Response)
+        mock_delete_response.status_code = 200
+        mock_delete_response.json.return_value = {
+            "message": "Dataset run deleted successfully"
+        }
+
+        def side_effect(request, *args, **kwargs):
+            url_str = str(request.url)
+            if "dataset-items" in url_str:
+                return mock_items_response
+            elif "/runs/" in url_str:
+                if request.method == "DELETE":
+                    return mock_delete_response
+                return mock_run_response
+            elif "/runs" in url_str:
+                return mock_runs_response
+            return mock_response
+
+        mock_send.side_effect = side_effect
+
+        langfuse = Langfuse(public_key="pk-test", secret_key="sk-test", base_url="http://localhost:3000")
+
+        # 1. get_dataset
+        langfuse.get_dataset("my/dataset")
+        langfuse.get_dataset("my dataset")
+
+        # 2. get_dataset_run
+        langfuse.get_dataset_run(dataset_name="my/dataset", run_name="my/run")
+        langfuse.get_dataset_run(dataset_name="my dataset", run_name="my run")
+
+        # 3. get_dataset_runs
+        langfuse.get_dataset_runs(dataset_name="my/dataset")
+        langfuse.get_dataset_runs(dataset_name="my dataset")
+
+        # 4. delete_dataset_run
+        langfuse.delete_dataset_run(dataset_name="my/dataset", run_name="my/run")
+        langfuse.delete_dataset_run(dataset_name="my dataset", run_name="my run")
+
+        # Collect all requested URLs
+        requested_urls = [str(call[0][0].url) for call in mock_send.call_args_list]
+        for url in requested_urls:
+            print(url)