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POST
/
v1
/
experiment
/
{experiment_id}
/
fetch
Fetch experiment (POST form)
curl --request POST \
  --url https://api.braintrust.dev/v1/experiment/{experiment_id}/fetch \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "limit": 1,
  "cursor": "<string>",
  "max_xact_id": "<string>",
  "max_root_span_id": "<string>",
  "version": "<string>"
}'
{
  "events": [
    {
      "id": "<string>",
      "_xact_id": "<string>",
      "created": "2023-11-07T05:31:56Z",
      "_pagination_key": "<string>",
      "project_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "experiment_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "input": "<any>",
      "output": "<any>",
      "expected": "<any>",
      "error": "<any>",
      "scores": {},
      "metadata": {
        "model": "<string>"
      },
      "tags": [
        "<string>"
      ],
      "metrics": {
        "start": 123,
        "end": 123,
        "prompt_tokens": 123,
        "completion_tokens": 123,
        "tokens": 123,
        "caller_functionname": "<any>",
        "caller_filename": "<any>",
        "caller_lineno": "<any>"
      },
      "context": {
        "caller_functionname": "<string>",
        "caller_filename": "<string>",
        "caller_lineno": 123
      },
      "span_id": "<string>",
      "span_parents": [
        "<string>"
      ],
      "root_span_id": "<string>",
      "span_attributes": {
        "name": "<string>",
        "type": "llm"
      },
      "is_root": true,
      "origin": {
        "object_type": "project_logs",
        "object_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
        "id": "<string>",
        "_xact_id": "<string>",
        "created": "<string>"
      }
    }
  ],
  "cursor": "<string>"
}

Authorizations

​
Authorization
string
header
required

Most Braintrust endpoints are authenticated by providing your API key as a header Authorization: Bearer [api_key] to your HTTP request. You can create an API key in the Braintrust organization settings page.

Path Parameters

​
experiment_id
string<uuid>
required

Experiment id

Body

application/json

Filters for the fetch query

​
limit
integer | null

limit the number of traces fetched

Fetch queries may be paginated if the total result size is expected to be large (e.g. project_logs which accumulate over a long time). Note that fetch queries only support pagination in descending time order (from latest to earliest _xact_id. Furthermore, later pages may return rows which showed up in earlier pages, except with an earlier _xact_id. This happens because pagination occurs over the whole version history of the event log. You will most likely want to exclude any such duplicate, outdated rows (by id) from your combined result set.

The limit parameter controls the number of full traces to return. So you may end up with more individual rows than the specified limit if you are fetching events containing traces.

Required range: x >= 0
​
cursor
string | null

An opaque string to be used as a cursor for the next page of results, in order from latest to earliest.

The string can be obtained directly from the cursor property of the previous fetch query

​
max_xact_id
string

DEPRECATION NOTICE: The manually-constructed pagination cursor is deprecated in favor of the explicit 'cursor' returned by object fetch requests. Please prefer the 'cursor' argument going forwards.

Together, max_xact_id and max_root_span_id form a pagination cursor

Since a paginated fetch query returns results in order from latest to earliest, the cursor for the next page can be found as the row with the minimum (earliest) value of the tuple (_xact_id, root_span_id). See the documentation of limit for an overview of paginating fetch queries.

​
max_root_span_id
string

DEPRECATION NOTICE: The manually-constructed pagination cursor is deprecated in favor of the explicit 'cursor' returned by object fetch requests. Please prefer the 'cursor' argument going forwards.

Together, max_xact_id and max_root_span_id form a pagination cursor

Since a paginated fetch query returns results in order from latest to earliest, the cursor for the next page can be found as the row with the minimum (earliest) value of the tuple (_xact_id, root_span_id). See the documentation of limit for an overview of paginating fetch queries.

​
version
string

Retrieve a snapshot of events from a past time

The version id is essentially a filter on the latest event transaction id. You can use the max_xact_id returned by a past fetch as the version to reproduce that exact fetch.

Response

Returns the fetched rows

​
events
object[]
required

A list of fetched events

​
cursor
string | null

Pagination cursor

Pass this string directly as the cursor param to your next fetch request to get the next page of results. Not provided if the returned result set is empty.