Class CallbackHandler

awaitHandlers

ignoreAgent

ignoreChain

ignoreCustomEvent

ignoreLLM

ignoreRetriever

lc_kwargs

lc_serializable

raiseError

lc_aliases

• get lc_aliases(): undefined | { [key: string]: string }

  A map of aliases for constructor args. Keys are the attribute names, e.g. "foo". Values are the alias that will replace the key in serialization. This is used to eg. make argument names match Python.

  Returns undefined | { [key: string]: string }

lc_attributes

• get lc_attributes(): undefined | { [key: string]: string }

  A map of additional attributes to merge with constructor args. Keys are the attribute names, e.g. "foo". Values are the attribute values, which will be serialized. These attributes need to be accepted by the constructor as arguments.

  Returns undefined | { [key: string]: string }

lc_id

• get lc_id(): string[]

  The final serialized identifier for the module.

  Returns string[]

lc_namespace

• get lc_namespace(): ["langchain_core", "callbacks", string]

  A path to the module that contains the class, eg. ["langchain", "llms"] Usually should be the same as the entrypoint the class is exported from.

  Returns ["langchain_core", "callbacks", string]

lc_secrets

• get lc_secrets(): undefined | { [key: string]: string }

  A map of secrets, which will be omitted from serialization. Keys are paths to the secret in constructor args, e.g. "foo.bar.baz". Values are the secret ids, which will be used when deserializing.

  Returns undefined | { [key: string]: string }

lc_serializable_keys

• get lc_serializable_keys(): undefined | string[]

  A manual list of keys that should be serialized. If not overridden, all fields passed into the constructor will be serialized.

  Returns undefined | string[]

copy

• copy(): BaseCallbackHandler

  Returns BaseCallbackHandler

OptionalhandleCustomEvent

• handleCustomEvent(
      eventName: string,
      data: any,
      runId: string,
      tags?: string[],
      metadata?: Record<string, any>,
  ): any

  Parameters

  • eventName: string
  • data: any
  • runId: string
  • Optionaltags: string[]
  • Optionalmetadata: Record<string, any>

  Returns any

OptionalhandleText

• handleText(
      text: string,
      runId: string,
      parentRunId?: string,
      tags?: string[],
  ): void | Promise<void>

  Parameters

  • text: string
  • runId: string
  • OptionalparentRunId: string
  • Optionaltags: string[]

  Returns void | Promise<void>

toJSON

• toJSON(): Serialized

  Returns Serialized

toJSONNotImplemented

• toJSONNotImplemented(): SerializedNotImplemented

  Returns SerializedNotImplemented

StaticfromMethods

• fromMethods(
      methods: BaseCallbackHandlerMethodsClass,
  ): {
      awaitHandlers: boolean;
      ignoreAgent: boolean;
      ignoreChain: boolean;
      ignoreCustomEvent: boolean;
      ignoreLLM: boolean;
      ignoreRetriever: boolean;
      lc_aliases: undefined | { [key: string]: string };
      lc_attributes: undefined | { [key: string]: string };
      lc_id: string[];
      lc_kwargs: SerializedFields;
      lc_namespace: ["langchain_core", "callbacks", string];
      lc_secrets: undefined | { [key: string]: string };
      lc_serializable: boolean;
      lc_serializable_keys: undefined | string[];
      name: string;
      raiseError: boolean;
      copy(): BaseCallbackHandler;
      handleAgentAction(
          action: AgentAction,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): void | Promise<void>;
      handleAgentEnd(
          action: AgentFinish,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): void | Promise<void>;
      handleChainEnd(
          outputs: ChainValues,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          kwargs?: { inputs?: Record<string, unknown> },
      ): any;
      handleChainError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          kwargs?: { inputs?: Record<string, unknown> },
      ): any;
      handleChainStart(
          chain: Serialized,
          inputs: ChainValues,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runType?: string,
          runName?: string,
      ): any;
      handleChatModelStart(
          llm: Serialized,
          messages: BaseMessage[][],
          runId: string,
          parentRunId?: string,
          extraParams?: Record<string, unknown>,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runName?: string,
      ): any;
      handleCustomEvent(
          eventName: string,
          data: any,
          runId: string,
          tags?: string[],
          metadata?: Record<string, any>,
      ): any;
      handleLLMEnd(
          output: LLMResult,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          extraParams?: Record<string, unknown>,
      ): any;
      handleLLMError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          extraParams?: Record<string, unknown>,
      ): any;
      handleLLMNewToken(
          token: string,
          idx: NewTokenIndices,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          fields?: HandleLLMNewTokenCallbackFields,
      ): any;
      handleLLMStart(
          llm: Serialized,
          prompts: string[],
          runId: string,
          parentRunId?: string,
          extraParams?: Record<string, unknown>,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runName?: string,
      ): any;
      handleRetrieverEnd(
          documents: DocumentInterface<Record<string, any>>[],
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any;
      handleRetrieverError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any;
      handleRetrieverStart(
          retriever: Serialized,
          query: string,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          metadata?: Record<string, unknown>,
          name?: string,
      ): any;
      handleText(
          text: string,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): void | Promise<void>;
      handleToolEnd(
          output: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any;
      handleToolError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any;
      handleToolStart(
          tool: Serialized,
          input: string,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runName?: string,
      ): any;
      toJSON(): Serialized;
      toJSONNotImplemented(): SerializedNotImplemented;
  }

  Parameters

  • methods: BaseCallbackHandlerMethodsClass

  Returns {
      awaitHandlers: boolean;
      ignoreAgent: boolean;
      ignoreChain: boolean;
      ignoreCustomEvent: boolean;
      ignoreLLM: boolean;
      ignoreRetriever: boolean;
      lc_aliases: undefined | { [key: string]: string };
      lc_attributes: undefined | { [key: string]: string };
      lc_id: string[];
      lc_kwargs: SerializedFields;
      lc_namespace: ["langchain_core", "callbacks", string];
      lc_secrets: undefined | { [key: string]: string };
      lc_serializable: boolean;
      lc_serializable_keys: undefined | string[];
      name: string;
      raiseError: boolean;
      copy(): BaseCallbackHandler;
      handleAgentAction(
          action: AgentAction,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): void | Promise<void>;
      handleAgentEnd(
          action: AgentFinish,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): void | Promise<void>;
      handleChainEnd(
          outputs: ChainValues,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          kwargs?: { inputs?: Record<string, unknown> },
      ): any;
      handleChainError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          kwargs?: { inputs?: Record<string, unknown> },
      ): any;
      handleChainStart(
          chain: Serialized,
          inputs: ChainValues,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runType?: string,
          runName?: string,
      ): any;
      handleChatModelStart(
          llm: Serialized,
          messages: BaseMessage[][],
          runId: string,
          parentRunId?: string,
          extraParams?: Record<string, unknown>,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runName?: string,
      ): any;
      handleCustomEvent(
          eventName: string,
          data: any,
          runId: string,
          tags?: string[],
          metadata?: Record<string, any>,
      ): any;
      handleLLMEnd(
          output: LLMResult,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          extraParams?: Record<string, unknown>,
      ): any;
      handleLLMError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          extraParams?: Record<string, unknown>,
      ): any;
      handleLLMNewToken(
          token: string,
          idx: NewTokenIndices,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          fields?: HandleLLMNewTokenCallbackFields,
      ): any;
      handleLLMStart(
          llm: Serialized,
          prompts: string[],
          runId: string,
          parentRunId?: string,
          extraParams?: Record<string, unknown>,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runName?: string,
      ): any;
      handleRetrieverEnd(
          documents: DocumentInterface<Record<string, any>>[],
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any;
      handleRetrieverError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any;
      handleRetrieverStart(
          retriever: Serialized,
          query: string,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          metadata?: Record<string, unknown>,
          name?: string,
      ): any;
      handleText(
          text: string,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): void | Promise<void>;
      handleToolEnd(
          output: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any;
      handleToolError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any;
      handleToolStart(
          tool: Serialized,
          input: string,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runName?: string,
      ): any;
      toJSON(): Serialized;
      toJSONNotImplemented(): SerializedNotImplemented;
  }

  • awaitHandlers: boolean

  • ignoreAgent: boolean

  • ignoreChain: boolean

  • ignoreCustomEvent: boolean

  • ignoreLLM: boolean

  • ignoreRetriever: boolean

  • Readonlylc_aliases: undefined | { [key: string]: string }

  • Readonlylc_attributes: undefined | { [key: string]: string }

  • Readonlylc_id: string[]

    The final serialized identifier for the module.

  • lc_kwargs: SerializedFields

  • Readonlylc_namespace: ["langchain_core", "callbacks", string]

  • Readonlylc_secrets: undefined | { [key: string]: string }

  • lc_serializable: boolean

  • Readonlylc_serializable_keys: undefined | string[]

  • name: string

  • raiseError: boolean

  • copy: function

    • copy(): BaseCallbackHandler

      Returns BaseCallbackHandler

  • handleAgentAction?: function

    • handleAgentAction(
          action: AgentAction,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): void | Promise<void>

      Called when an agent is about to execute an action, with the action and the run ID.

      Parameters

      • action: AgentAction
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]

      Returns void | Promise<void>

  • handleAgentEnd?: function

    • handleAgentEnd(
          action: AgentFinish,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): void | Promise<void>

      Called when an agent finishes execution, before it exits. with the final output and the run ID.

      Parameters

      • action: AgentFinish
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]

      Returns void | Promise<void>

  • handleChainEnd?: function

    • handleChainEnd(
          outputs: ChainValues,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          kwargs?: { inputs?: Record<string, unknown> },
      ): any

      Called at the end of a Chain run, with the outputs and the run ID.

      Parameters

      • outputs: ChainValues
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]
      • Optionalkwargs: { inputs?: Record<string, unknown> }

      Returns any

  • handleChainError?: function

    • handleChainError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          kwargs?: { inputs?: Record<string, unknown> },
      ): any

      Called if a Chain run encounters an error

      Parameters

      • err: any
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]
      • Optionalkwargs: { inputs?: Record<string, unknown> }

      Returns any

  • handleChainStart?: function

    • handleChainStart(
          chain: Serialized,
          inputs: ChainValues,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runType?: string,
          runName?: string,
      ): any

      Called at the start of a Chain run, with the chain name and inputs and the run ID.

      Parameters

      • chain: Serialized
      • inputs: ChainValues
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]
      • Optionalmetadata: Record<string, unknown>
      • OptionalrunType: string
      • OptionalrunName: string

      Returns any

  • handleChatModelStart?: function

    • handleChatModelStart(
          llm: Serialized,
          messages: BaseMessage[][],
          runId: string,
          parentRunId?: string,
          extraParams?: Record<string, unknown>,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runName?: string,
      ): any

      Called at the start of a Chat Model run, with the prompt(s) and the run ID.

      Parameters

      • llm: Serialized
      • messages: BaseMessage[][]
      • runId: string
      • OptionalparentRunId: string
      • OptionalextraParams: Record<string, unknown>
      • Optionaltags: string[]
      • Optionalmetadata: Record<string, unknown>
      • OptionalrunName: string

      Returns any

  • handleCustomEvent?: function

    • handleCustomEvent(
          eventName: string,
          data: any,
          runId: string,
          tags?: string[],
          metadata?: Record<string, any>,
      ): any

      Parameters

      • eventName: string
      • data: any
      • runId: string
      • Optionaltags: string[]
      • Optionalmetadata: Record<string, any>

      Returns any

  • handleLLMEnd?: function

    • handleLLMEnd(
          output: LLMResult,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          extraParams?: Record<string, unknown>,
      ): any

      Called at the end of an LLM/ChatModel run, with the output and the run ID.

      Parameters

      • output: LLMResult
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]
      • OptionalextraParams: Record<string, unknown>

      Returns any

  • handleLLMError?: function

    • handleLLMError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          extraParams?: Record<string, unknown>,
      ): any

      Called if an LLM/ChatModel run encounters an error

      Parameters

      • err: any
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]
      • OptionalextraParams: Record<string, unknown>

      Returns any

  • handleLLMNewToken?: function

    • handleLLMNewToken(
          token: string,
          idx: NewTokenIndices,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          fields?: HandleLLMNewTokenCallbackFields,
      ): any

      Called when an LLM/ChatModel in streaming mode produces a new token

      Parameters

      • token: string
      • idx: NewTokenIndices
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]
      • Optionalfields: HandleLLMNewTokenCallbackFields

      Returns any

  • handleLLMStart?: function

    • handleLLMStart(
          llm: Serialized,
          prompts: string[],
          runId: string,
          parentRunId?: string,
          extraParams?: Record<string, unknown>,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runName?: string,
      ): any

      Called at the start of an LLM or Chat Model run, with the prompt(s) and the run ID.

      Parameters

      • llm: Serialized
      • prompts: string[]
      • runId: string
      • OptionalparentRunId: string
      • OptionalextraParams: Record<string, unknown>
      • Optionaltags: string[]
      • Optionalmetadata: Record<string, unknown>
      • OptionalrunName: string

      Returns any

  • handleRetrieverEnd?: function

    • handleRetrieverEnd(
          documents: DocumentInterface<Record<string, any>>[],
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any

      Parameters

      • documents: DocumentInterface<Record<string, any>>[]
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]

      Returns any

  • handleRetrieverError?: function

    • handleRetrieverError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any

      Parameters

      • err: any
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]

      Returns any

  • handleRetrieverStart?: function

    • handleRetrieverStart(
          retriever: Serialized,
          query: string,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          metadata?: Record<string, unknown>,
          name?: string,
      ): any

      Parameters

      • retriever: Serialized
      • query: string
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]
      • Optionalmetadata: Record<string, unknown>
      • Optionalname: string

      Returns any

  • handleText?: function

    • handleText(
          text: string,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): void | Promise<void>

      Parameters

      • text: string
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]

      Returns void | Promise<void>

  • handleToolEnd?: function

    • handleToolEnd(
          output: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any

      Called at the end of a Tool run, with the tool output and the run ID.

      Parameters

      • output: any
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]

      Returns any

  • handleToolError?: function

    • handleToolError(
          err: any,
          runId: string,
          parentRunId?: string,
          tags?: string[],
      ): any

      Called if a Tool run encounters an error

      Parameters

      • err: any
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]

      Returns any

  • handleToolStart?: function

    • handleToolStart(
          tool: Serialized,
          input: string,
          runId: string,
          parentRunId?: string,
          tags?: string[],
          metadata?: Record<string, unknown>,
          runName?: string,
      ): any

      Called at the start of a Tool run, with the tool name and input and the run ID.

      Parameters

      • tool: Serialized
      • input: string
      • runId: string
      • OptionalparentRunId: string
      • Optionaltags: string[]
      • Optionalmetadata: Record<string, unknown>
      • OptionalrunName: string

      Returns any

  • toJSON: function

    • toJSON(): Serialized

      Returns Serialized

  • toJSONNotImplemented: function

    • toJSONNotImplemented(): SerializedNotImplemented

      Returns SerializedNotImplemented

Staticlc_name

• lc_name(): string

  The name of the serializable. Override to provide an alias or to preserve the serialized module name in minified environments.

  Implemented as a static method to support loading logic.

  Returns string