Class RetrievalQAChain

Class representing a chain for performing question-answering tasks with a retrieval component.

Example

// Initialize the OpenAI model and the remote retriever with the specified configuration
const model = new ChatOpenAI({});
const retriever = new RemoteLangChainRetriever({
  url: "http://example.com/api",
  auth: { bearer: "foo" },
  inputKey: "message",
  responseKey: "response",
});

// Create a RetrievalQAChain using the model and retriever
const chain = RetrievalQAChain.fromLLM(model, retriever);

// Execute the chain with a query and log the result
const res = await chain.call({
  query: "What did the president say about Justice Breyer?",
});
console.log({ res });

Hierarchy

BaseChain
- RetrievalQAChain

Implements

RetrievalQAChainInput

Index

Constructors

constructor

new RetrievalQAChain(fields): RetrievalQAChain
Parameters
- fields: RetrievalQAChainInput
Returns RetrievalQAChain
Overrides BaseChain.constructor
- Defined in docs/api_refs/langchain/src/chains/retrieval_qa.ts:77

Properties

combineDocumentsChain

combineDocumentsChain: BaseChain<ChainValues, ChainValues>

inputKey

inputKey: string = "query"

retriever

retriever: BaseRetriever

returnSourceDocuments

returnSourceDocuments: boolean = false

verbose

verbose: boolean

Whether to print out response text.

`Optional` callbacks

callbacks?: Callbacks

`Optional` memory

memory?: BaseMemory

`Optional` metadata

metadata?: Record<string, unknown>

`Optional` tags

tags?: string[]

Accessors

inputKeys

get inputKeys(): string[]
Returns string[]
Overrides BaseChain.inputKeys
- Defined in docs/api_refs/langchain/src/chains/retrieval_qa.ts:61

outputKeys

get outputKeys(): string[]
Returns string[]
Overrides BaseChain.outputKeys
- Defined in docs/api_refs/langchain/src/chains/retrieval_qa.ts:65

Methods

apply

apply(inputs, config?): Promise<ChainValues[]>
Call the chain on all inputs in the list
Parameters
- inputs: ChainValues[]
- Optional config: (BaseCallbackConfig | Callbacks)[]
Returns Promise<ChainValues[]>
Inherited from BaseChain.apply
- Defined in docs/api_refs/langchain/src/chains/base.ts:252

batch

batch(inputs, options?, batchOptions?): Promise<ChainValues[]>
Default implementation of batch, which calls invoke N times. Subclasses should override this method if they can batch more efficiently.
Parameters
- inputs: ChainValues[]
  
  Array of inputs to each batch call.
- Optional options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]
  
  Either a single call options object to apply to each batch call or an array for each call.
- Optional batchOptions: RunnableBatchOptions & {
  returnExceptions?: false;
  }
Returns Promise<ChainValues[]>
An array of RunOutputs, or mixed RunOutputs and errors if batchOptions.returnExceptions is set
Inherited from BaseChain.batch
- Defined in langchain-core/dist/runnables/base.d.ts:76
batch(inputs, options?, batchOptions?): Promise<(ChainValues | Error)[]>
Parameters
- inputs: ChainValues[]
- Optional options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]
- Optional batchOptions: RunnableBatchOptions & {
  returnExceptions: true;
  }
Returns Promise<(ChainValues | Error)[]>
Inherited from BaseChain.batch
- Defined in langchain-core/dist/runnables/base.d.ts:79
batch(inputs, options?, batchOptions?): Promise<(ChainValues | Error)[]>
Parameters
- inputs: ChainValues[]
- Optional options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]
- Optional batchOptions: RunnableBatchOptions
Returns Promise<(ChainValues | Error)[]>
Inherited from BaseChain.batch
- Defined in langchain-core/dist/runnables/base.d.ts:82

bind

bind(kwargs): Runnable<ChainValues, ChainValues, BaseCallbackConfig>
Bind arguments to a Runnable, returning a new Runnable.
Parameters
- kwargs: Partial<BaseCallbackConfig>
Returns Runnable<ChainValues, ChainValues, BaseCallbackConfig>
A new RunnableBinding that, when invoked, will apply the bound args.
Inherited from BaseChain.bind
- Defined in langchain-core/dist/runnables/base.d.ts:33

call

call(values, config?, tags?): Promise<ChainValues>
Run the core logic of this chain and add to output if desired.

Wraps _call and handles memory.
Parameters
- values: ChainValues & {
  signal?: AbortSignal;
  timeout?: number;
  }
- Optional config: BaseCallbackConfig | Callbacks
- Optional tags: string[]
  
  Deprecated
Returns Promise<ChainValues>
Inherited from BaseChain.call
- Defined in docs/api_refs/langchain/src/chains/base.ts:192

invoke

invoke(input, config?): Promise<ChainValues>
Invoke the chain with the provided input and returns the output.
Parameters
- input: ChainValues
  
  Input values for the chain run.
- Optional config: BaseCallbackConfig
  
  Optional configuration for the Runnable.
Returns Promise<ChainValues>
Promise that resolves with the output of the chain run.
Inherited from BaseChain.invoke
- Defined in docs/api_refs/langchain/src/chains/base.ts:83

map

map(): Runnable<ChainValues[], ChainValues[], BaseCallbackConfig>
Return a new Runnable that maps a list of inputs to a list of outputs, by calling invoke() with each input.

Returns Runnable<ChainValues[], ChainValues[], BaseCallbackConfig>
Inherited from BaseChain.map
- Defined in langchain-core/dist/runnables/base.d.ts:38

pipe

pipe<NewRunOutput>(coerceable): RunnableSequence<ChainValues, Exclude<NewRunOutput, Error>>
Create a new runnable sequence that runs each individual runnable in series, piping the output of one runnable into another runnable or runnable-like.
Type Parameters
- NewRunOutput
Parameters
- coerceable: RunnableLike<ChainValues, NewRunOutput>
  
  A runnable, function, or object whose values are functions or runnables.
Returns RunnableSequence<ChainValues, Exclude<NewRunOutput, Error>>
A new runnable sequence.
Inherited from BaseChain.pipe
- Defined in langchain-core/dist/runnables/base.d.ts:136

prepOutputs

prepOutputs(inputs, outputs, returnOnlyOutputs?): Promise<Record<string, unknown>>
Parameters
- inputs: Record<string, unknown>
- outputs: Record<string, unknown>
- returnOnlyOutputs: boolean = false
Returns Promise<Record<string, unknown>>
Inherited from BaseChain.prepOutputs
- Defined in docs/api_refs/langchain/src/chains/base.ts:99

run

run(input, config?): Promise<string>
Parameters
- input: any
- Optional config: BaseCallbackConfig | Callbacks
Returns Promise<string>
Inherited from BaseChain.run
- Defined in docs/api_refs/langchain/src/chains/base.ts:140

serialize

serialize(): SerializedVectorDBQAChain
Return a json-like object representing this chain.

Returns SerializedVectorDBQAChain
Overrides BaseChain.serialize
- Defined in docs/api_refs/langchain/src/chains/retrieval_qa.ts:125

stream

stream(input, options?): Promise<IterableReadableStream<ChainValues>>
Stream output in chunks.
Parameters
- input: ChainValues
- Optional options: Partial<BaseCallbackConfig>
Returns Promise<IterableReadableStream<ChainValues>>
A readable stream that is also an iterable.
Inherited from BaseChain.stream
- Defined in langchain-core/dist/runnables/base.d.ts:97

streamLog

streamLog(input, options?, streamOptions?): AsyncGenerator<RunLogPatch, any, unknown>
Stream all output from a runnable, as reported to the callback system. This includes all inner runs of LLMs, Retrievers, Tools, etc. Output is streamed as Log objects, which include a list of jsonpatch ops that describe how the state of the run has changed in each step, and the final state of the run. The jsonpatch ops can be applied in order to construct state.
Parameters
- input: ChainValues
- Optional options: Partial<BaseCallbackConfig>
- Optional streamOptions: Omit<LogStreamCallbackHandlerInput, "autoClose">
Returns AsyncGenerator<RunLogPatch, any, unknown>
Inherited from BaseChain.streamLog
- Defined in langchain-core/dist/runnables/base.d.ts:156

toJSON

toJSON(): Serialized
Returns Serialized
Inherited from BaseChain.toJSON
- Defined in langchain-core/dist/load/serializable.d.ts:72

toJSONNotImplemented

toJSONNotImplemented(): SerializedNotImplemented
Returns SerializedNotImplemented
Inherited from BaseChain.toJSONNotImplemented
- Defined in langchain-core/dist/load/serializable.d.ts:73

transform

transform(generator, options): AsyncGenerator<ChainValues, any, unknown>
Default implementation of transform, which buffers input and then calls stream. Subclasses should override this method if they can start producing output while input is still being generated.
Parameters
- generator: AsyncGenerator<ChainValues, any, unknown>
- options: Partial<BaseCallbackConfig>
Returns AsyncGenerator<ChainValues, any, unknown>
Inherited from BaseChain.transform
- Defined in langchain-core/dist/runnables/base.d.ts:144

withConfig

withConfig(config): RunnableBinding<ChainValues, ChainValues, BaseCallbackConfig>
Bind config to a Runnable, returning a new Runnable.
Parameters
- config: BaseCallbackConfig
  
  New configuration parameters to attach to the new runnable.
Returns RunnableBinding<ChainValues, ChainValues, BaseCallbackConfig>
A new RunnableBinding with a config matching what's passed.
Inherited from BaseChain.withConfig
- Defined in langchain-core/dist/runnables/base.d.ts:53

withFallbacks

withFallbacks(fields): RunnableWithFallbacks<ChainValues, ChainValues>
Create a new runnable from the current one that will try invoking other passed fallback runnables if the initial invocation fails.
Parameters
- fields: {
  fallbacks: Runnable<ChainValues, ChainValues, BaseCallbackConfig>[];
  }
  - fallbacks: Runnable<ChainValues, ChainValues, BaseCallbackConfig>[]
    
    Other runnables to call if the runnable errors.
Returns RunnableWithFallbacks<ChainValues, ChainValues>
A new RunnableWithFallbacks.
Inherited from BaseChain.withFallbacks
- Defined in langchain-core/dist/runnables/base.d.ts:60

withListeners

withListeners(params): Runnable<ChainValues, ChainValues, BaseCallbackConfig>
Bind lifecycle listeners to a Runnable, returning a new Runnable. The Run object contains information about the run, including its id, type, input, output, error, startTime, endTime, and any tags or metadata added to the run.
Parameters
- params: {
      onEnd?: ((run, config?) => void | Promise<void>);
      onError?: ((run, config?) => void | Promise<void>);
      onStart?: ((run, config?) => void | Promise<void>);
  }
  
  The object containing the callback functions.
  - Optional onEnd?: ((run, config?) => void | Promise<void>)
    - (run, config?): void | Promise<void>
      
      Called after the runnable finishes running, with the Run object.
      
      Parameters
      
      run: Run
      
      Optional config: BaseCallbackConfig
      
      Returns void | Promise<void>
  - Optional onError?: ((run, config?) => void | Promise<void>)
    - (run, config?): void | Promise<void>
      
      Called if the runnable throws an error, with the Run object.
      
      Parameters
      
      run: Run
      
      Optional config: BaseCallbackConfig
      
      Returns void | Promise<void>
  - Optional onStart?: ((run, config?) => void | Promise<void>)
    - (run, config?): void | Promise<void>
      
      Called before the runnable starts running, with the Run object.
      
      Parameters
      
      run: Run
      
      Optional config: BaseCallbackConfig
      
      Returns void | Promise<void>
Returns Runnable<ChainValues, ChainValues, BaseCallbackConfig>
Inherited from BaseChain.withListeners
- Defined in langchain-core/dist/runnables/base.d.ts:169

withRetry

withRetry(fields?): RunnableRetry<ChainValues, ChainValues, BaseCallbackConfig>
Add retry logic to an existing runnable.
Parameters
- Optional fields: {
  onFailedAttempt?: RunnableRetryFailedAttemptHandler;
  stopAfterAttempt?: number;
  }
  - Optional onFailedAttempt?: RunnableRetryFailedAttemptHandler
  - Optional stopAfterAttempt?: number
Returns RunnableRetry<ChainValues, ChainValues, BaseCallbackConfig>
A new RunnableRetry that, when invoked, will retry according to the parameters.
Inherited from BaseChain.withRetry
- Defined in langchain-core/dist/runnables/base.d.ts:44

`Static` deserialize

deserialize(_data, _values): Promise<RetrievalQAChain>
Load a chain from a json-like object describing it.
Parameters
- _data: SerializedVectorDBQAChain
- _values: LoadValues
Returns Promise<RetrievalQAChain>
Overrides BaseChain.deserialize
- Defined in docs/api_refs/langchain/src/chains/retrieval_qa.ts:118

`Static` fromLLM

fromLLM(llm, retriever, options?): RetrievalQAChain
Creates a new instance of RetrievalQAChain using a BaseLanguageModel and a BaseRetriever.
Parameters
- llm: BaseLanguageModel<any, BaseLanguageModelCallOptions>
  
  The BaseLanguageModel used to generate a new question.
- retriever: BaseRetriever
  
  The BaseRetriever used to retrieve relevant documents.
- Optional options: Partial<Omit<RetrievalQAChainInput, "combineDocumentsChain" | "retriever" | "index">> & StuffQAChainParams
  
  Optional parameters for the RetrievalQAChain.
Returns RetrievalQAChain
A new instance of RetrievalQAChain.
- Defined in docs/api_refs/langchain/src/chains/retrieval_qa.ts:137

`Static` isRunnable

isRunnable(thing): thing is Runnable<any, any, BaseCallbackConfig>
Parameters
- thing: any
Returns thing is Runnable<any, any, BaseCallbackConfig>
Inherited from BaseChain.isRunnable
- Defined in langchain-core/dist/runnables/base.d.ts:157

Class RetrievalQAChain

Example

Hierarchy

Implements

Index

Constructors

Properties

Accessors

Methods

Constructors

constructor

Parameters

fields: RetrievalQAChainInput

Returns RetrievalQAChain

Properties

combineDocumentsChain

inputKey

retriever

returnSourceDocuments

verbose

Optional callbacks

Optional memory

Optional metadata

Optional tags

Accessors

inputKeys

Returns string[]

outputKeys

Returns string[]

Methods

apply

Parameters

inputs: ChainValues[]

Optional config: (BaseCallbackConfig | Callbacks)[]

Returns Promise<ChainValues[]>

batch

Parameters

inputs: ChainValues[]

Optional options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]

Optional batchOptions: RunnableBatchOptions & { returnExceptions?: false; }

Returns Promise<ChainValues[]>

Parameters

inputs: ChainValues[]

Optional options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]

Optional batchOptions: RunnableBatchOptions & { returnExceptions: true; }

Returns Promise<(ChainValues | Error)[]>

Parameters

inputs: ChainValues[]

Optional options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]

Optional batchOptions: RunnableBatchOptions

Returns Promise<(ChainValues | Error)[]>

bind

Parameters

kwargs: Partial<BaseCallbackConfig>

Returns Runnable<ChainValues, ChainValues, BaseCallbackConfig>

call

Parameters

values: ChainValues & { signal?: AbortSignal; timeout?: number; }

Optional config: BaseCallbackConfig | Callbacks

Optional tags: string[]

Deprecated

Returns Promise<ChainValues>

invoke

Parameters

input: ChainValues

Optional config: BaseCallbackConfig

Returns Promise<ChainValues>

map

Returns Runnable<ChainValues[], ChainValues[], BaseCallbackConfig>

pipe

Type Parameters

NewRunOutput

Parameters

coerceable: RunnableLike<ChainValues, NewRunOutput>

Returns RunnableSequence<ChainValues, Exclude<NewRunOutput, Error>>

prepOutputs

Parameters

inputs: Record<string, unknown>

outputs: Record<string, unknown>

returnOnlyOutputs: boolean = false

`Optional` callbacks

`Optional` memory

`Optional` metadata

`Optional` tags

`Optional` config: (BaseCallbackConfig | Callbacks)[]

`Optional` options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]

`Optional` batchOptions: RunnableBatchOptions & {
returnExceptions?: false;
}

`Optional` options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]

`Optional` batchOptions: RunnableBatchOptions & {
returnExceptions: true;
}

`Optional` options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]

`Optional` batchOptions: RunnableBatchOptions

values: ChainValues & {
signal?: AbortSignal;
timeout?: number;
}

`Optional` config: BaseCallbackConfig | Callbacks

`Optional` tags: string[]

`Optional` config: BaseCallbackConfig

`Optional` config: BaseCallbackConfig | Callbacks

`Optional` options: Partial<BaseCallbackConfig>

`Optional` options: Partial<BaseCallbackConfig>

`Optional` streamOptions: Omit<LogStreamCallbackHandlerInput, "autoClose">

fields: {
fallbacks: Runnable<ChainValues, ChainValues, BaseCallbackConfig>[];
}

params: {
onEnd?: ((run, config?) => void | Promise<void>);
onError?: ((run, config?) => void | Promise<void>);
onStart?: ((run, config?) => void | Promise<void>);
}

`Optional` onEnd?: ((run, config?) => void | Promise<void>)

`Optional` config: BaseCallbackConfig

`Optional` onError?: ((run, config?) => void | Promise<void>)

`Optional` config: BaseCallbackConfig

`Optional` onStart?: ((run, config?) => void | Promise<void>)

`Optional` config: BaseCallbackConfig

`Optional` fields: {
onFailedAttempt?: RunnableRetryFailedAttemptHandler;
stopAfterAttempt?: number;
}

`Optional` onFailedAttempt?: RunnableRetryFailedAttemptHandler

`Optional` stopAfterAttempt?: number

`Static` deserialize

`Static` fromLLM