DeepchecksCallbackHandler

class DeepchecksCallbackHandler(BaseCallbackHandler)

LangChain callback handler that streams chain, LLM, and tool events to the Deepchecks LLM platform.

Attach this handler to a LangChain runnable to automatically capture each step
of an interaction (prompts, responses, tool invocations, errors) and log it as
a Deepchecks interaction under the configured application/version.

Attributes

Attribute	Description
`information_retrieval`	Documents or context passages retrieved during the current interaction.
`input`	The input prompt captured at the start of the current interaction.
`output`	The model output captured at the end of the current interaction.
`started_at`	UTC timestamp marking when the current interaction began.
`steps`	Intermediate steps recorded during the current interaction, one per LangChain run.
`user_interaction_id`	The user-supplied identifier for the current interaction, as a string.

Methods

Method	Description
`on_chain_end`	Run when chain ends running.
`on_chain_start`	Run when chain starts running.
`on_chat_model_start`	Run when ChatModel starts running.
`on_llm_end`	Run when LLM ends running.
`on_llm_error`	Run when LLM errors.
`on_llm_start`	Run when LLM starts running.
`on_retriever_end`	Run when Retriever ends running.
`on_retriever_error`	Run when Retriever errors.
`on_retriever_start`	Run when Retriever starts running.

information_retrieval

@property
def information_retrieval() -> list[str]

Documents or context passages retrieved during the current interaction.

Returns

list[str]

input

@property
def input() -> str

The input prompt captured at the start of the current interaction.

Returns

str

output

@property
def output() -> str

The model output captured at the end of the current interaction.

Returns

str

started_at

@property
def started_at() -> Union[datetime, None]

UTC timestamp marking when the current interaction began.

Returns

datetime | None

steps

@property
def steps() -> List[Step]

Intermediate steps recorded during the current interaction, one per LangChain run.

Returns

List[Step]

user_interaction_id

@property
def user_interaction_id() -> Union[str, None]

The user-supplied identifier for the current interaction, as a string.

Returns

str | None

on_chain_end

def on_chain_end(outputs: Dict[str, Any], **kwargs: Any) -> Any

Run when chain ends running.

Parameters

outputs (Dict[str, Any])
**kwargs (Any)

Returns

Any

on_chain_start

def on_chain_start(serialized: Dict[str, Any],
                   inputs: Dict[str, Any],
                   *,
                   run_id: UUID,
                   parent_run_id: Optional[UUID] = None,
                   tags: Optional[List[str]] = None,
                   metadata: Optional[Dict[str, Any]] = None,
                   **kwargs: Any) -> None

Run when chain starts running.

Parameters

serialized (Dict[str, Any])
inputs (Dict[str, Any])
run_id (UUID)
parent_run_id (UUID | None, default=None)
tags (List[str] | None, default=None)
metadata (Dict[str, Any] | None, default=None)
**kwargs (Any)

Returns

None

on_chat_model_start

def on_chat_model_start(serialized: Dict[str, Any],
                        messages: List[List[BaseMessage]],
                        *,
                        run_id: UUID,
                        parent_run_id: Optional[UUID] = None,
                        tags: Optional[List[str]] = None,
                        metadata: Optional[Dict[str, Any]] = None,
                        **kwargs: Any) -> Any

Run when ChatModel starts running.

Parameters

serialized (Dict[str, Any])
messages (List[List[BaseMessage]])
run_id (UUID)
parent_run_id (UUID | None, default=None)
tags (List[str] | None, default=None)
metadata (Dict[str, Any] | None, default=None)
**kwargs (Any)

Returns

Any

on_llm_end

def on_llm_end(response: LLMResult, **kwargs: Any) -> Any

Run when LLM ends running.

Parameters

response (LLMResult)
**kwargs (Any)

Returns

Any

on_llm_error

def on_llm_error(error: Union[Exception, KeyboardInterrupt], **kwargs: Any) -> Any

Run when LLM errors.

Parameters

error (Exception | KeyboardInterrupt)
**kwargs (Any)

Returns

Any

on_llm_start

def on_llm_start(serialized: Dict[str, Any], prompts: List[str], **kwargs: Any) -> Any

Run when LLM starts running.

Parameters

serialized (Dict[str, Any])
prompts (List[str])
**kwargs (Any)

Returns

Any

on_retriever_end

def on_retriever_end(documents: Sequence[Document],
                     *,
                     run_id: UUID,
                     parent_run_id: Optional[UUID] = None,
                     **kwargs: Any) -> Any

Run when Retriever ends running.

Parameters

documents (Sequence[Document])
run_id (UUID)
parent_run_id (UUID | None, default=None)
**kwargs (Any)

Returns

Any

on_retriever_error

def on_retriever_error(error: BaseException,
                       *,
                       run_id: UUID,
                       parent_run_id: Optional[UUID] = None,
                       **kwargs: Any) -> Any

Run when Retriever errors.

Parameters

error (BaseException)
run_id (UUID)
parent_run_id (UUID | None, default=None)
**kwargs (Any)

Returns

Any

on_retriever_start

def on_retriever_start(serialized: Dict[str, Any],
                       query: str,
                       *,
                       run_id: UUID,
                       parent_run_id: Optional[UUID] = None,
                       tags: Optional[List[str]] = None,
                       metadata: Optional[Dict[str, Any]] = None,
                       **kwargs: Any) -> Any

Run when Retriever starts running.

Parameters

serialized (Dict[str, Any])
query (str)
run_id (UUID)
parent_run_id (UUID | None, default=None)
tags (List[str] | None, default=None)
metadata (Dict[str, Any] | None, default=None)
**kwargs (Any)

Returns

Any