Class: Langfuse::ApiClient

Inherits:
Object
  • Object
show all
Includes:
PromptCacheEvents, ReadApi
Defined in:
lib/langfuse/api_client.rb

Overview

HTTP client for Langfuse API

Handles authentication, connection management, and HTTP requests to the Langfuse REST API.

Examples:

api_client = Langfuse::ApiClient.new(
  public_key: "pk_...",
  secret_key: "sk_...",
  base_url: "https://cloud.langfuse.com",
  timeout: 5,
  logger: Logger.new($stdout)
)

Constant Summary

Constants included from PromptCacheEvents

PromptCacheEvents::PROMPT_CACHE_NOTIFICATION

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from ReadApi

#list_observations, #list_scores, #query_metrics

Methods included from PromptCacheEvents

build_payload, #emit_prompt_cache_event, #emit_prompt_fallback_event, #setup_prompt_cache_events

Constructor Details

#initialize(public_key:, secret_key:, base_url:, timeout: 5, logger: nil, cache: nil, cache_observer: nil) ⇒ ApiClient

Initialize a new API client

rubocop:disable Metrics/ParameterLists

Parameters:

  • public_key (String) —

    Langfuse public API key

  • secret_key (String) —

    Langfuse secret API key

  • base_url (String) —

    Base URL for Langfuse API

  • timeout (Integer) (defaults to: 5) —

    HTTP request timeout in seconds

  • logger (Logger) (defaults to: nil) —

    Logger instance for debugging

  • cache (PromptCache, RailsCacheAdapter, nil) (defaults to: nil) —

    Optional cache for prompt responses

  • cache_observer (#call, nil) (defaults to: nil) —

    Optional observer for prompt cache events



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# File 'lib/langfuse/api_client.rb', line 60

def initialize(public_key:, secret_key:, base_url:, timeout: 5, logger: nil, cache: nil, cache_observer: nil)
  @public_key = public_key
  @secret_key = secret_key
  @base_url = base_url
  @timeout = timeout
  @logger = logger || Logger.new($stdout, level: Logger::WARN)
  @cache = cache
  setup_prompt_cache_events(cache_observer: cache_observer)
  @prompt_cache_coordinator = PromptCacheCoordinator.new(
    cache: cache,
    event_emitter: self,
    fetch_prompt: ->(name, version:, label:) { fetch_prompt_from_api(name, version: version, label: label) }
  )
end

Instance Attribute Details

#base_url ⇒ String (readonly)

Returns Base URL for Langfuse API.

Returns:

  • (String) —

    Base URL for Langfuse API



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# File 'lib/langfuse/api_client.rb', line 38

def base_url
  @base_url
end

#cache ⇒ PromptCache, ... (readonly)

Returns Optional cache for prompt responses.

Returns:



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# File 'lib/langfuse/api_client.rb', line 47

def cache
  @cache
end

#logger ⇒ Logger (readonly)

Returns Logger instance for debugging.

Returns:

  • (Logger) —

    Logger instance for debugging



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# File 'lib/langfuse/api_client.rb', line 44

def logger
  @logger
end

#public_key ⇒ String (readonly)

Returns Langfuse public API key.

Returns:

  • (String) —

    Langfuse public API key



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# File 'lib/langfuse/api_client.rb', line 32

def public_key
  @public_key
end

#secret_key ⇒ String (readonly)

Returns Langfuse secret API key.

Returns:

  • (String) —

    Langfuse secret API key



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# File 'lib/langfuse/api_client.rb', line 35

def secret_key
  @secret_key
end

#timeout ⇒ Integer (readonly)

Returns HTTP request timeout in seconds.

Returns:

  • (Integer) —

    HTTP request timeout in seconds



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# File 'lib/langfuse/api_client.rb', line 41

def timeout
  @timeout
end

Instance Method Details

#clear_prompt_cache ⇒ Integer?

Logically clear the whole Langfuse prompt cache namespace.

Returns:

  • (Integer, nil) —

    New global generation, or nil when cache is disabled



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# File 'lib/langfuse/api_client.rb', line 194

def clear_prompt_cache
  @prompt_cache_coordinator.clear_prompt_cache
end

#connection(timeout: nil) ⇒ Faraday::Connection

Get a Faraday connection

Parameters:

  • timeout (Integer, nil) (defaults to: nil) —

    Optional custom timeout for this connection

Returns:

  • (Faraday::Connection) 


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# File 'lib/langfuse/api_client.rb', line 80

def connection(timeout: nil)
  if timeout
    # Create dedicated connection for custom timeout
    # to avoid mutating shared connection
    build_connection(timeout: timeout)
  else
    @connection ||= build_connection
  end
end

#create_dataset(name:, description: nil, metadata: nil) ⇒ Hash

Create a new dataset

Examples:

data = api_client.create_dataset(name: "my-dataset", description: "QA evaluation set")

Parameters:

  • name (String) —

    Dataset name (required)

  • description (String, nil) (defaults to: nil) —

    Optional description

  • metadata (Hash, nil) (defaults to: nil) —

    Optional metadata hash

Returns:

  • (Hash) —

    The created dataset data

Raises:



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# File 'lib/langfuse/api_client.rb', line 527

def create_dataset(name:, description: nil, metadata: nil)
  request(:post, "/api/public/v2/datasets",
          body: { name: name, description: description, metadata: metadata }.compact)
end

#create_dataset_item(dataset_name:, input: nil, expected_output: nil, metadata: nil, id: nil, source_trace_id: nil, source_observation_id: nil, status: nil) ⇒ Hash

Create a new dataset item (or upsert if id is provided)

rubocop:disable Metrics/ParameterLists

Examples:

data = api_client.create_dataset_item(
  dataset_name: "my-dataset",
  input: { query: "What is Ruby?" },
  expected_output: { answer: "A programming language" }
)

Parameters:

  • dataset_name (String) —

    Name of the dataset (required)

  • input (Object, nil) (defaults to: nil) —

    Input data for the item

  • expected_output (Object, nil) (defaults to: nil) —

    Expected output for evaluation

  • metadata (Hash, nil) (defaults to: nil) —

    Optional metadata

  • id (String, nil) (defaults to: nil) —

    Optional ID for upsert behavior

  • source_trace_id (String, nil) (defaults to: nil) —

    Link to source trace

  • source_observation_id (String, nil) (defaults to: nil) —

    Link to source observation

  • status (Symbol, nil) (defaults to: nil) —

    Item status (:active or :archived)

Returns:

  • (Hash) —

    The created dataset item data

Raises:



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# File 'lib/langfuse/api_client.rb', line 553

def create_dataset_item(dataset_name:, input: nil, expected_output: nil,
                        metadata: nil, id: nil, source_trace_id: nil,
                        source_observation_id: nil, status: nil)
  payload = {
    datasetName: dataset_name, id: id, input: input,
    expectedOutput: expected_output, metadata: metadata,
    sourceTraceId: source_trace_id, sourceObservationId: source_observation_id,
    status: status&.to_s&.upcase
  }.compact
  request(:post, "/api/public/dataset-items", body: payload)
end

#create_dataset_run_item(dataset_item_id:, run_name:, trace_id: nil, observation_id: nil, metadata: nil, run_description: nil) ⇒ Hash

Create a dataset run item (link a trace to a dataset item within a run)

Examples:

api_client.create_dataset_run_item(dataset_item_id: "item-123", run_name: "eval-v1", trace_id: "trace-abc")

Parameters:

  • dataset_item_id (String) —

    Dataset item ID (required)

  • run_name (String) —

    Run name (required)

  • trace_id (String, nil) (defaults to: nil) —

    Trace ID to link

  • observation_id (String, nil) (defaults to: nil) —

    Observation ID to link

  • metadata (Hash, nil) (defaults to: nil) —

    Optional metadata

  • run_description (String, nil) (defaults to: nil) —

    Optional run description

Returns:

  • (Hash) —

    The created dataset run item data

Raises:



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# File 'lib/langfuse/api_client.rb', line 337

def create_dataset_run_item(dataset_item_id:, run_name:, trace_id: nil,
                            observation_id: nil, metadata: nil, run_description: nil)
  payload = {
    datasetItemId: dataset_item_id, runName: run_name,
    traceId: trace_id, observationId: observation_id,
    metadata: metadata, runDescription: run_description
  }.compact
  request(:post, "/api/public/dataset-run-items", body: payload)
end

#create_prompt(name:, prompt:, type:, config: {}, labels: [], tags: [], commit_message: nil) ⇒ Hash

Create a new prompt (or new version if prompt with same name exists)

rubocop:disable Metrics/ParameterLists

Examples:

Create a text prompt

api_client.create_prompt(
  name: "greeting",
  prompt: "Hello {{name}}!",
  type: "text",
  labels: ["production"]
)

Parameters:

  • name (String) —

    The prompt name

  • prompt (String, Array<Hash>) —

    The prompt content

  • type (String) —

    Prompt type ("text" or "chat")

  • config (Hash) (defaults to: {}) —

    Optional configuration (model params, etc.)

  • labels (Array<String>) (defaults to: []) —

    Optional labels (e.g., ["production"])

  • tags (Array<String>) (defaults to: []) —

    Optional tags

  • commit_message (String, nil) (defaults to: nil) —

    Optional commit message

Returns:

  • (Hash) —

    The created prompt data

Raises:



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# File 'lib/langfuse/api_client.rb', line 238

def create_prompt(name:, prompt:, type:, config: {}, labels: [], tags: [], commit_message: nil)
  payload = {
    name: name, prompt: prompt, type: type, config: config,
    labels: labels, tags: tags, commitMessage: commit_message
  }.compact
  request(:post, "/api/public/v2/prompts", body: payload)
    .tap { @prompt_cache_coordinator.invalidate_after_mutation(name) }
end

#create_score(payload:) ⇒ String

Create a score through the synchronous Scores API.

Parameters:

  • payload (Hash) —

    Validated score attributes in API format

Returns:

  • (String) —

    ID of the created score

Raises:



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# File 'lib/langfuse/api_client.rb', line 315

def create_score(payload:)
  response = request(:post, "/api/public/scores", body: payload)
  score_id = response["id"]
  return score_id if score_id.is_a?(String) && !score_id.empty?

  raise ApiError, "Score creation response did not include an id"
end

#delete_dataset_item(id) ⇒ Hash

Note:

404 responses are treated as success to keep DELETE idempotent across retries

Delete a dataset item by ID

Examples:

api_client.delete_dataset_item("item-uuid-123")

Parameters:

  • id (String) —

    Dataset item ID

Returns:

  • (Hash) —

    The response body

Raises:



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# File 'lib/langfuse/api_client.rb', line 620

def delete_dataset_item(id)
  response = connection.delete("/api/public/dataset-items/#{URI.encode_uri_component(id)}")
  handle_delete_dataset_item_response(response, id)
rescue Faraday::RetriableResponse => e
  logger.error("Faraday error: Retries exhausted - #{e.response.status}")
  handle_delete_dataset_item_response(e.response, id)
rescue Faraday::Error => e
  logger.error("Faraday error: #{e.message}")
  raise ApiError, "HTTP request failed: #{e.message}"
end

#delete_dataset_run(dataset_name:, run_name:) ⇒ Hash?

Note:

404 responses raise NotFoundError to preserve strict delete semantics

Delete a dataset run by name

Parameters:

  • dataset_name (String) —

    Dataset name (required)

  • run_name (String) —

    Run name (required)

Returns:

  • (Hash, nil) —

    Response body, or nil for 204 responses

Raises:



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# File 'lib/langfuse/api_client.rb', line 388

def delete_dataset_run(dataset_name:, run_name:)
  with_faraday_error_handling do
    response = connection.delete(dataset_run_path(dataset_name: dataset_name, run_name: run_name))
    response.status == 204 ? nil : handle_response(response)
  end
end

#get_dataset(name) ⇒ Hash

Fetch a dataset by name

Examples:

data = api_client.get_dataset("my-dataset")

Parameters:

  • name (String) —

    Dataset name (supports folder paths like "evaluation/qa-dataset")

Returns:

  • (Hash) —

    The dataset data

Raises:



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# File 'lib/langfuse/api_client.rb', line 512

def get_dataset(name)
  request(:get, "/api/public/v2/datasets/#{URI.encode_uri_component(name)}")
end

#get_dataset_item(id) ⇒ Hash

Fetch a dataset item by ID

Examples:

data = api_client.get_dataset_item("item-uuid-123")

Parameters:

  • id (String) —

    Dataset item ID

Returns:

  • (Hash) —

    The dataset item data

Raises:



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# File 'lib/langfuse/api_client.rb', line 576

def get_dataset_item(id)
  request(:get, "/api/public/dataset-items/#{URI.encode_uri_component(id)}")
end

#get_dataset_run(dataset_name:, run_name:) ⇒ Hash

Fetch a dataset run by dataset and run name

Parameters:

  • dataset_name (String) —

    Dataset name (required)

  • run_name (String) —

    Run name (required)

Returns:

  • (Hash) —

    The dataset run data

Raises:



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# File 'lib/langfuse/api_client.rb', line 355

def get_dataset_run(dataset_name:, run_name:)
  request(:get, dataset_run_path(dataset_name: dataset_name, run_name: run_name))
end

#get_projects ⇒ Hash

Fetch projects accessible with the current API keys

Examples:

data = api_client.get_projects
project_id = data["data"][0]["id"]

Returns:

  • (Hash) —

    The parsed response body containing project data

Raises:



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# File 'lib/langfuse/api_client.rb', line 404

def get_projects # rubocop:disable Naming/AccessorMethodName
  request(:get, "/api/public/projects")
end

#get_prompt(name, version: nil, label: nil, cache_ttl: nil) ⇒ Hash

Fetch a prompt from the Langfuse API

Checks cache first if caching is enabled. On cache miss, fetches from API and stores in cache. When using Rails.cache backend, uses distributed lock to prevent cache stampedes.

Parameters:

  • name (String) —

    The name of the prompt

  • version (Integer, nil) (defaults to: nil) —

    Optional specific version number

  • label (String, nil) (defaults to: nil) —

    Optional label (e.g., "production", "latest")

  • cache_ttl (Integer, nil) (defaults to: nil) —

    Optional TTL override for this fetch

Returns:

  • (Hash) —

    The prompt data

Raises:

  • (ArgumentError) —

    if both version and label are provided

  • (NotFoundError) —

    if the prompt is not found

  • (UnauthorizedError) —

    if authentication fails

  • (ApiError) —

    for other API errors



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# File 'lib/langfuse/api_client.rb', line 125

def get_prompt(name, version: nil, label: nil, cache_ttl: nil)
  get_prompt_result(name, version: version, label: label, cache_ttl: cache_ttl).prompt
end

#get_prompt_result(name, version: nil, label: nil, cache_ttl: nil) ⇒ PromptFetchResult

Fetch a prompt and include cache metadata.

Parameters:

  • name (String) —

    The name of the prompt

  • version (Integer, nil) (defaults to: nil) —

    Optional specific version number

  • label (String, nil) (defaults to: nil) —

    Optional label (e.g., "production", "latest")

  • cache_ttl (Integer, nil) (defaults to: nil) —

    Optional TTL override for this fetch

Returns:

Raises:

  • (ArgumentError) —

    if both version and label are provided

  • (ArgumentError) —

    if cache_ttl is negative

  • (NotFoundError) —

    if the prompt is not found

  • (UnauthorizedError) —

    if authentication fails

  • (ApiError) —

    for other API errors



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# File 'lib/langfuse/api_client.rb', line 141

def get_prompt_result(name, version: nil, label: nil, cache_ttl: nil)
  @prompt_cache_coordinator.get_prompt_result(name, version: version, label: label, cache_ttl: cache_ttl)
end

#get_trace(id) ⇒ Hash

Fetch a trace by ID

Examples:

trace = api_client.get_trace("trace-uuid-123")

Parameters:

  • id (String) —

    Trace ID

Returns:

  • (Hash) —

    The trace data

Raises:



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# File 'lib/langfuse/api_client.rb', line 484

def get_trace(id)
  request(:get, "/api/public/traces/#{URI.encode_uri_component(id)}")
end

#invalidate_prompt_cache(name, version: nil, label: nil) ⇒ PromptCacheKey

Invalidate one exact logical prompt cache key.

Parameters:

  • name (String) —

    The prompt name

  • version (Integer, nil) (defaults to: nil) —

    Optional specific version number

  • label (String, nil) (defaults to: nil) —

    Optional label

Returns:

Raises:

  • (ArgumentError) —

    if both version and label are provided



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# File 'lib/langfuse/api_client.rb', line 179

def invalidate_prompt_cache(name, version: nil, label: nil)
  @prompt_cache_coordinator.invalidate_prompt_cache(name, version: version, label: label)
end

#invalidate_prompt_cache_by_name(name) ⇒ Integer?

Invalidate all cached variants for one prompt name.

Parameters:

  • name (String) —

    The prompt name

Returns:

  • (Integer, nil) —

    New generation, or nil when cache is disabled



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# File 'lib/langfuse/api_client.rb', line 187

def invalidate_prompt_cache_by_name(name)
  @prompt_cache_coordinator.invalidate_prompt_cache_by_name(name)
end

#list_dataset_items ⇒ Array<Hash>

List items in a dataset with optional filters

Examples:

items = api_client.list_dataset_items(dataset_name: "my-dataset", limit: 50)

Parameters:

  • dataset_name (String) —

    Name of the dataset (required)

  • page (Integer, nil) —

    Optional page number for pagination

  • limit (Integer, nil) —

    Optional limit per page

  • source_trace_id (String, nil) —

    Filter by source trace ID

  • source_observation_id (String, nil) —

    Filter by source observation ID

Returns:

  • (Array<Hash>) —

    Array of dataset item hashes

Raises:



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# File 'lib/langfuse/api_client.rb', line 593

def list_dataset_items(**)
  list_dataset_items_paginated(**)["data"] || []
end

#list_dataset_items_paginated(dataset_name:, page: nil, limit: nil, source_trace_id: nil, source_observation_id: nil) ⇒ Hash

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Full paginated response including "meta" for internal pagination use

Returns:

  • (Hash) —

    Full response hash with "data" array and "meta" pagination info



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# File 'lib/langfuse/api_client.rb', line 601

def list_dataset_items_paginated(dataset_name:, page: nil, limit: nil,
                                 source_trace_id: nil, source_observation_id: nil)
  params = {
    datasetName: dataset_name, page: page, limit: limit,
    sourceTraceId: source_trace_id, sourceObservationId: source_observation_id
  }.compact
  request(:get, "/api/public/dataset-items", params: params)
end

#list_dataset_runs(dataset_name:, page: nil, limit: nil) ⇒ Array<Hash>

List dataset runs in a dataset

Parameters:

  • dataset_name (String) —

    Dataset name (required)

  • page (Integer, nil) (defaults to: nil) —

    Optional page number for pagination

  • limit (Integer, nil) (defaults to: nil) —

    Optional limit per page

Returns:

  • (Array<Hash>) —

    Array of dataset run hashes

Raises:



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# File 'lib/langfuse/api_client.rb', line 367

def list_dataset_runs(dataset_name:, page: nil, limit: nil)
  list_dataset_runs_paginated(dataset_name: dataset_name, page: page, limit: limit)["data"] || []
end

#list_dataset_runs_paginated(dataset_name:, page: nil, limit: nil) ⇒ Hash

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Full paginated response including "meta" for internal pagination use

Returns:

  • (Hash) —

    Full response hash with "data" array and "meta" pagination info



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# File 'lib/langfuse/api_client.rb', line 375

def list_dataset_runs_paginated(dataset_name:, page: nil, limit: nil)
  request(:get, dataset_runs_path(dataset_name), params: { page: page, limit: limit }.compact)
end

#list_datasets(page: nil, limit: nil) ⇒ Array<Hash>

List all datasets in the project

Examples:

datasets = api_client.list_datasets(page: 1, limit: 10)

Parameters:

  • page (Integer, nil) (defaults to: nil) —

    Optional page number for pagination

  • limit (Integer, nil) (defaults to: nil) —

    Optional limit per page

Returns:

  • (Array<Hash>) —

    Array of dataset metadata hashes

Raises:



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# File 'lib/langfuse/api_client.rb', line 498

def list_datasets(page: nil, limit: nil)
  request(:get, "/api/public/v2/datasets", params: { page: page, limit: limit }.compact)["data"] || []
end

#list_prompts(page: nil, limit: nil) ⇒ Array<Hash>

List all prompts in the Langfuse project

Fetches a list of all prompt names available in your project. Note: This returns metadata only, not full prompt content.

Examples:

prompts = api_client.list_prompts
prompts.each do |prompt|
  puts "#{prompt['name']} (v#{prompt['version']})"
end

Parameters:

  • page (Integer, nil) (defaults to: nil) —

    Optional page number for pagination

  • limit (Integer, nil) (defaults to: nil) —

    Optional limit per page (default: API default)

Returns:

  • (Array<Hash>) —

    Array of prompt metadata hashes

Raises:



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# File 'lib/langfuse/api_client.rb', line 106

def list_prompts(page: nil, limit: nil)
  request(:get, "/api/public/v2/prompts", params: { page: page, limit: limit }.compact)["data"] || []
end

#list_traces(page: nil, limit: nil, user_id: nil, name: nil, session_id: nil, from_timestamp: nil, to_timestamp: nil, order_by: nil, tags: nil, version: nil, release: nil, environment: nil, fields: nil, filter: nil) ⇒ Array<Hash>

List traces in the project

rubocop:disable Metrics/ParameterLists

Examples:

traces = api_client.list_traces(page: 1, limit: 10, name: "my-trace")

Parameters:

  • page (Integer, nil) (defaults to: nil) —

    Optional page number for pagination

  • limit (Integer, nil) (defaults to: nil) —

    Optional limit per page

  • user_id (String, nil) (defaults to: nil) —

    Filter by user ID

  • name (String, nil) (defaults to: nil) —

    Filter by trace name

  • session_id (String, nil) (defaults to: nil) —

    Filter by session ID

  • from_timestamp (Time, nil) (defaults to: nil) —

    Filter traces after this time

  • to_timestamp (Time, nil) (defaults to: nil) —

    Filter traces before this time

  • order_by (String, nil) (defaults to: nil) —

    Order by field

  • tags (Array<String>, nil) (defaults to: nil) —

    Filter by tags

  • version (String, nil) (defaults to: nil) —

    Filter by version

  • release (String, nil) (defaults to: nil) —

    Filter by release

  • environment (String, nil) (defaults to: nil) —

    Filter by environment

  • fields (String, nil) (defaults to: nil) —

    Comma-separated field groups to include (e.g. "core,scores,metrics")

  • filter (String, nil) (defaults to: nil) —

    JSON string for advanced filtering

Returns:

  • (Array<Hash>) —

    Array of trace hashes

Raises:



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# File 'lib/langfuse/api_client.rb', line 440

def list_traces(page: nil, limit: nil, user_id: nil, name: nil, session_id: nil,
                from_timestamp: nil, to_timestamp: nil, order_by: nil,
                tags: nil, version: nil, release: nil, environment: nil,
                fields: nil, filter: nil)
  list_traces_paginated(
    page: page, limit: limit, user_id: user_id, name: name,
    session_id: session_id, from_timestamp: from_timestamp,
    to_timestamp: to_timestamp, order_by: order_by, tags: tags,
    version: version, release: release, environment: environment,
    fields: fields, filter: filter
  )["data"] || []
end

#list_traces_paginated(page: nil, limit: nil, user_id: nil, name: nil, session_id: nil, from_timestamp: nil, to_timestamp: nil, order_by: nil, tags: nil, version: nil, release: nil, environment: nil, fields: nil, filter: nil) ⇒ Hash

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Full paginated response including "meta" for internal pagination use

rubocop:disable Metrics/ParameterLists

Returns:

  • (Hash) —

    Full response hash with "data" array and "meta" pagination info



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# File 'lib/langfuse/api_client.rb', line 459

def list_traces_paginated(page: nil, limit: nil, user_id: nil, name: nil, session_id: nil,
                          from_timestamp: nil, to_timestamp: nil, order_by: nil,
                          tags: nil, version: nil, release: nil, environment: nil,
                          fields: nil, filter: nil)
  params = build_traces_params(
    page: page, limit: limit, user_id: user_id, name: name,
    session_id: session_id, from_timestamp: from_timestamp,
    to_timestamp: to_timestamp, order_by: order_by, tags: tags,
    version: version, release: release, environment: environment,
    fields: fields, filter: filter
  )
  request(:get, "/api/public/traces", params: params)
end

#prompt_cache_key(name, version: nil, label: nil) ⇒ PromptCacheKey

Inspect the logical and generated cache keys for a prompt.

Parameters:

  • name (String) —

    The prompt name

  • version (Integer, nil) (defaults to: nil) —

    Optional specific version number

  • label (String, nil) (defaults to: nil) —

    Optional label

Returns:

Raises:

  • (ArgumentError) —

    if both version and label are provided



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# File 'lib/langfuse/api_client.rb', line 168

def prompt_cache_key(name, version: nil, label: nil)
  @prompt_cache_coordinator.prompt_cache_key(name, version: version, label: label)
end

#prompt_cache_stats ⇒ Hash

Return prompt cache statistics.

Returns:

  • (Hash) —

    Cache statistics



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# File 'lib/langfuse/api_client.rb', line 201

def prompt_cache_stats
  @prompt_cache_coordinator.prompt_cache_stats
end

#refresh_prompt(name, version: nil, label: nil, cache_ttl: nil) ⇒ PromptFetchResult

Refresh a prompt from the API, optionally writing through to cache.

Parameters:

  • name (String) —

    The name of the prompt

  • version (Integer, nil) (defaults to: nil) —

    Optional specific version number

  • label (String, nil) (defaults to: nil) —

    Optional label

  • cache_ttl (Integer, nil) (defaults to: nil) —

    Optional TTL override for this refresh

Returns:

Raises:

  • (ArgumentError) —

    if both version and label are provided

  • (ArgumentError) —

    if cache_ttl is negative

  • (NotFoundError) —

    if the prompt is not found

  • (UnauthorizedError) —

    if authentication fails

  • (ApiError) —

    for other API errors



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# File 'lib/langfuse/api_client.rb', line 157

def refresh_prompt(name, version: nil, label: nil, cache_ttl: nil)
  @prompt_cache_coordinator.refresh_prompt(name, version: version, label: label, cache_ttl: cache_ttl)
end

#send_batch(events) ⇒ void

This method returns an undefined value.

Send a batch of events to the Langfuse ingestion API

Sends events (scores, traces, observations) to the ingestion endpoint. Retries transient errors (429, 503, 504, network errors) with exponential backoff. Batch operations are idempotent (events have unique IDs), so retries are safe.

Examples:

events = [
  {
    id: SecureRandom.uuid,
    type: "score-create",
    timestamp: Time.now.iso8601,
    body: { name: "quality", value: 0.85, trace_id: "abc123..." }
  }
]
api_client.send_batch(events)

Parameters:

  • events (Array<Hash>) —

    Array of event hashes to send

Raises:

  • (ArgumentError) —

    if events is not an Array or is empty

  • (UnauthorizedError) —

    if authentication fails

  • (ApiError) —

    for other API errors after retries exhausted



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# File 'lib/langfuse/api_client.rb', line 295

def send_batch(events)
  raise ArgumentError, "events must be an array" unless events.is_a?(Array)
  raise ArgumentError, "events array cannot be empty" if events.empty?

  response = connection.post("/api/public/ingestion", { batch: events })
  handle_batch_response(response)
rescue Faraday::RetriableResponse => e
  logger.error("Langfuse batch send failed: Retries exhausted - #{e.response.status}")
  handle_batch_response(e.response)
rescue Faraday::Error => e
  logger.error("Langfuse batch send failed: #{e.message}")
  raise BatchDeliveryError.new("Batch send failed: #{e.message}", retryable: true)
end

#shutdown ⇒ void

This method returns an undefined value.

Shut down the API client and release resources

Shuts down the cache backend's SWR thread pool when present.



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# File 'lib/langfuse/api_client.rb', line 413

def shutdown
  @cache&.shutdown
end

#update_prompt(name:, version:, labels:) ⇒ Hash

Update labels for an existing prompt version

Examples:

Promote a prompt to production

api_client.update_prompt(
  name: "greeting",
  version: 2,
  labels: ["production"]
)

Parameters:

  • name (String) —

    The prompt name

  • version (Integer) —

    The version number to update

  • labels (Array<String>) —

    New labels (replaces existing). Required.

Returns:

  • (Hash) —

    The updated prompt data

Raises:



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# File 'lib/langfuse/api_client.rb', line 265

def update_prompt(name:, version:, labels:)
  raise ArgumentError, "labels must be an array" unless labels.is_a?(Array)

  path = "/api/public/v2/prompts/#{URI.encode_uri_component(name)}/versions/#{version}"
  request(:patch, path, body: { newLabels: labels })
    .tap { @prompt_cache_coordinator.invalidate_after_mutation(name) }
end

#validate_prompt_cache_backend! ⇒ Boolean

Validate the configured prompt cache backend.

rubocop:disable Naming/PredicateMethod

Returns:

  • (Boolean) —

    true when the configured backend is usable

Raises:



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# File 'lib/langfuse/api_client.rb', line 210

def validate_prompt_cache_backend!
  @cache&.validate!
  true
end