Class SequentialChain

Chain where the outputs of one chain feed directly into next.

Example

const promptTemplate = new PromptTemplate({
  template: `You are a playwright. Given the title of play and the era it is set in, it is your job to write a synopsis for that title.
Title: {title}
Era: {era}
Playwright: This is a synopsis for the above play:`,
  inputVariables: ["title", "era"],
});

const reviewPromptTemplate = new PromptTemplate({
  template: `You are a play critic from the New York Times. Given the synopsis of play, it is your job to write a review for that play.
  
    Play Synopsis:
    {synopsis}
    Review from a New York Times play critic of the above play:`,
  inputVariables: ["synopsis"],
});

const overallChain = new SequentialChain({
  chains: [
    new LLMChain({
      llm: new ChatOpenAI({ temperature: 0 }),
      prompt: promptTemplate,
      outputKey: "synopsis",
    }),
    new LLMChain({
      llm: new OpenAI({ temperature: 0 }),
      prompt: reviewPromptTemplate,
      outputKey: "review",
    }),
  ],
  inputVariables: ["era", "title"],
  outputVariables: ["synopsis", "review"],
  verbose: true,
});

const chainExecutionResult = await overallChain.call({
  title: "Tragedy at sunset on the beach",
  era: "Victorian England",
});
console.log(chainExecutionResult);

Hierarchy

BaseChain
- SequentialChain

Implements

SequentialChainInput

Index

Constructors

constructor

new SequentialChain(fields): SequentialChain
Parameters
- fields: SequentialChainInput
Returns SequentialChain
Overrides BaseChain.constructor
- Defined in docs/api_refs/langchain/src/chains/sequential_chain.ts:99

Properties

chains

chains: BaseChain<ChainValues, ChainValues>[]

Array of chains to run as a sequence. The chains are run in order they appear in the array.

inputVariables

inputVariables: string[]

Defines which variables should be passed as initial input to the first chain.

outputVariables

outputVariables: string[]

Which variables should be returned as a result of executing the chain. If not specified, output of the last of the chains is used.

verbose

verbose: boolean

Whether to print out response text.

`Optional` callbacks

callbacks?: Callbacks

`Optional` memory

memory?: BaseMemory

`Optional` metadata

metadata?: Record<string, unknown>

`Optional` returnAll

returnAll?: boolean

Whether or not to return all intermediate outputs and variables (excluding initial input variables).

`Optional` tags

tags?: string[]

Accessors

inputKeys

get inputKeys(): string[]
Returns string[]
Overrides BaseChain.inputKeys
- Defined in docs/api_refs/langchain/src/chains/sequential_chain.ts:91

outputKeys

get outputKeys(): string[]
Returns string[]
Overrides BaseChain.outputKeys
- Defined in docs/api_refs/langchain/src/chains/sequential_chain.ts:95

Methods

apply

apply(inputs, config?): Promise<ChainValues[]>
Call the chain on all inputs in the list
Parameters
- inputs: ChainValues[]
- Optional config: (Callbacks | BaseCallbackConfig)[]
Returns Promise<ChainValues[]>
Inherited from BaseChain.apply
- Defined in docs/api_refs/langchain/src/chains/base.ts:225

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 docs/api_refs/langchain/src/schema/runnable/base.ts:159
batch(inputs, options?, batchOptions?): Promise<(Error | ChainValues)[]>
Parameters
- inputs: ChainValues[]
- Optional options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]
- Optional batchOptions: RunnableBatchOptions & {
  returnExceptions: true;
  }
Returns Promise<(Error | ChainValues)[]>
Inherited from BaseChain.batch
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:165
batch(inputs, options?, batchOptions?): Promise<(Error | ChainValues)[]>
Parameters
- inputs: ChainValues[]
- Optional options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]
- Optional batchOptions: RunnableBatchOptions
Returns Promise<(Error | ChainValues)[]>
Inherited from BaseChain.batch
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:171

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 docs/api_refs/langchain/src/schema/runnable/base.ts:67

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: Callbacks | BaseCallbackConfig
- Optional tags: string[]
  
  Deprecated
Returns Promise<ChainValues>
Inherited from BaseChain.call
- Defined in docs/api_refs/langchain/src/chains/base.ts:165

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 docs/api_refs/langchain/src/schema/runnable/base.ts:78

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 docs/api_refs/langchain/src/schema/runnable/base.ts:461

run

run(input, config?): Promise<string>
Parameters
- input: any
- Optional config: Callbacks | BaseCallbackConfig
Returns Promise<string>
Inherited from BaseChain.run
- Defined in docs/api_refs/langchain/src/chains/base.ts:113

serialize

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

Returns SerializedSequentialChain
Overrides BaseChain.serialize
- Defined in docs/api_refs/langchain/src/chains/sequential_chain.ts:226

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 docs/api_refs/langchain/src/schema/runnable/base.ts:225

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 docs/api_refs/langchain/src/schema/runnable/base.ts:507

toJSON

toJSON(): Serialized
Returns Serialized
Inherited from BaseChain.toJSON
- Defined in docs/api_refs/langchain/src/load/serializable.ts:148

toJSONNotImplemented

toJSONNotImplemented(): SerializedNotImplemented
Returns SerializedNotImplemented
Inherited from BaseChain.toJSONNotImplemented
- Defined in docs/api_refs/langchain/src/load/serializable.ts:222

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 docs/api_refs/langchain/src/schema/runnable/base.ts:478

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 docs/api_refs/langchain/src/schema/runnable/base.ts:107

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 docs/api_refs/langchain/src/schema/runnable/base.ts:124

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 docs/api_refs/langchain/src/schema/runnable/base.ts:88

`Static` deserialize

deserialize(data): Promise<SequentialChain>
Load a chain from a json-like object describing it.
Parameters
- data: SerializedSequentialChain
Returns Promise<SequentialChain>
Overrides BaseChain.deserialize
- Defined in docs/api_refs/langchain/src/chains/sequential_chain.ts:214

`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 docs/api_refs/langchain/src/schema/runnable/base.ts:557

Class SequentialChain

Example

Hierarchy

Implements

Index

Constructors

Properties

Accessors

Methods

Constructors

constructor

Parameters

fields: SequentialChainInput

Returns SequentialChain

Properties

chains

inputVariables

outputVariables

verbose

Optional callbacks

Optional memory

Optional metadata

Optional returnAll

Optional tags

Accessors

inputKeys

Returns string[]

outputKeys

Returns string[]

Methods

apply

Parameters

inputs: ChainValues[]

Optional config: (Callbacks | BaseCallbackConfig)[]

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<(Error | ChainValues)[]>

Parameters

inputs: ChainValues[]

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

Optional batchOptions: RunnableBatchOptions

Returns Promise<(Error | ChainValues)[]>

bind

Parameters

kwargs: Partial<BaseCallbackConfig>

Returns Runnable<ChainValues, ChainValues, BaseCallbackConfig>

call

Parameters

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

Optional config: Callbacks | BaseCallbackConfig

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>>

run

Parameters

input: any

Optional config: Callbacks | BaseCallbackConfig

Returns Promise<string>

`Optional` callbacks

`Optional` memory

`Optional` metadata

`Optional` returnAll

`Optional` tags

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

`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: Callbacks | BaseCallbackConfig

`Optional` tags: string[]

`Optional` config: BaseCallbackConfig

`Optional` config: Callbacks | BaseCallbackConfig

`Optional` options: Partial<BaseCallbackConfig>

`Optional` options: Partial<BaseCallbackConfig>

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

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

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

`Optional` onFailedAttempt?: RunnableRetryFailedAttemptHandler

`Optional` stopAfterAttempt?: number

`Static` deserialize

`Static` isRunnable