Public API does not allow filter by scores

[kaikiat]

This is my code snippet.

url = f"{settings.langfuse_host}/api/public/traces"
params = {
    'page': page,
    'limit': limit,
    'name': 'Summarize error',
    'filter': json.dumps([
        {
            "type": "numberObject",
            "column": "scores",
            "operator": ">",
            "key": "toxicity",
            "value": 0.01,
        }
    ])
}

response = requests.get(url, headers=headers, params=params)

I am getting this error

response = {"message":"Internal Server Error","error":"Unknown expression or function identifier `s.scores_avg` in scope SELECT count() AS count FROM traces AS t WHERE (project_id = 'ABCD') AND (empty(arrayFilter(x -> (((x.1) = 'toxicity') AND ((x.2) > _CAST('0.01', 'Decimal64(12)'))), s.scores_avg)) = 0) AND (t.name = 'Summarize error'). "}

I am using Langfuse v3.117.2

Does anyone know how to solve this ? Thank you

[inkeep-ai-assistant[bot]]

The issue you're experiencing is that the /api/public/traces endpoint doesn't support filtering by scores through the filter parameter in the way you're attempting(1).

Instead, you should use the /api/public/v2/scores endpoint to filter scores directly, then retrieve the associated traces(2). Here's the recommended approach:

Step 1: Query scores with your filter criteria

url = f"{settings.langfuse_host}/api/public/v2/scores"
params = {
    'page': page,
    'limit': limit,
    'name': 'toxicity',
    'operator': '>',
    'value': 0.01,
    'dataType': 'NUMERIC'
}

response = requests.get(url, headers=headers, params=params)
scores_data = response.json()

(2)

Step 2: Extract trace IDs from the scores response

trace_ids = [score['traceId'] for score in scores_data['data']]

Step 3: Fetch individual traces

for trace_id in trace_ids:
    trace_url = f"{settings.langfuse_host}/api/public/traces/{trace_id}"
    trace_response = requests.get(trace_url, headers=headers)
    # Process trace data

(1)

Important Note: There is a known open issue with the scores API operator parameter where filtering with certain operators (particularly =) may not behave as expected(3)(4). The > operator you're using has been reported to have issues as well in some cases(3). If you encounter unexpected results, this may be related to that ongoing issue.

Alternatively, you can use the Langfuse Python SDK which provides a more convenient interface:

from langfuse import Langfuse

langfuse = Langfuse()

# This approach is recommended in the documentation
trace = langfuse.get_trace(trace_id)
scores = trace["scores"]

(4)

📚 Sources:

1. Traces
2. GET /api/public/v2/scores
3. bug: public scores API operator parameter odd behavior
4. API - /scores not respecting value when operator '='

---

Have another question? Just tag @inkeep.