Class StringOutputParser

OutputParser that parses LLMResult into the top likely string.

Example

const promptTemplate = PromptTemplate.fromTemplate(
  "Tell me a joke about {topic}",
);

const chain = RunnableSequence.from([
  promptTemplate,
  new ChatOpenAI({}),
  new StringOutputParser(),
]);

const result = await chain.invoke({ topic: "bears" });
console.log("What do you call a bear with no teeth? A gummy bear!");

Hierarchy

BaseTransformOutputParser<string>
- StringOutputParser

Index

Constructors

constructor

Properties

name?

Constructors

constructor

new StringOutputParser(kwargs?, ..._args): StringOutputParser
Parameters
- Optional kwargs: SerializedFields
- Rest ..._args: never[]
Returns StringOutputParser
Inherited from BaseTransformOutputParser.constructor
- Defined in langchain-core/src/load/serializable.ts:136

Properties

`Optional` name

name?: string

Methods

assign

assign(mapping): Runnable<any, any, RunnableConfig>
Assigns new fields to the dict output of this runnable. Returns a new runnable.
Parameters
- mapping: RunnableMapLike<Record<string, unknown>, Record<string, unknown>>
Returns Runnable<any, any, RunnableConfig>
Inherited from BaseTransformOutputParser.assign
- Defined in langchain-core/src/runnables/base.ts:576

batch

batch(inputs, options?, batchOptions?): Promise<string[]>
Default implementation of batch, which calls invoke N times. Subclasses should override this method if they can batch more efficiently.
Parameters
- inputs: (string | BaseMessage)[]
  
  Array of inputs to each batch call.
- Optional options: Partial<RunnableConfig> | Partial<RunnableConfig>[]
  
  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<string[]>
An array of RunOutputs, or mixed RunOutputs and errors if batchOptions.returnExceptions is set
Inherited from BaseTransformOutputParser.batch
- Defined in langchain-core/src/runnables/base.ts:247
batch(inputs, options?, batchOptions?): Promise<(string | Error)[]>
Parameters
- inputs: (string | BaseMessage)[]
- Optional options: Partial<RunnableConfig> | Partial<RunnableConfig>[]
- Optional batchOptions: RunnableBatchOptions & {
  returnExceptions: true;
  }
Returns Promise<(string | Error)[]>
Inherited from BaseTransformOutputParser.batch
- Defined in langchain-core/src/runnables/base.ts:253
batch(inputs, options?, batchOptions?): Promise<(string | Error)[]>
Parameters
- inputs: (string | BaseMessage)[]
- Optional options: Partial<RunnableConfig> | Partial<RunnableConfig>[]
- Optional batchOptions: RunnableBatchOptions
Returns Promise<(string | Error)[]>
Inherited from BaseTransformOutputParser.batch
- Defined in langchain-core/src/runnables/base.ts:259

bind

bind(kwargs): Runnable<string | BaseMessage, string, RunnableConfig>
Bind arguments to a Runnable, returning a new Runnable.
Parameters
- kwargs: Partial<RunnableConfig>
Returns Runnable<string | BaseMessage, string, RunnableConfig>
A new RunnableBinding that, when invoked, will apply the bound args.
Inherited from BaseTransformOutputParser.bind
- Defined in langchain-core/src/runnables/base.ts:157

getFormatInstructions

getFormatInstructions(): string
Return a string describing the format of the output.

Returns string
Format instructions.
Example
```
{
 "foo": "bar"
}
```
Overrides BaseTransformOutputParser.getFormatInstructions
- Defined in langchain-core/src/output_parsers/string.ts:42

getName

getName(suffix?): string
Parameters
- Optional suffix: string
Returns string
Inherited from BaseTransformOutputParser.getName
- Defined in langchain-core/src/runnables/base.ts:140

invoke

invoke(input, options?): Promise<string>
Calls the parser with a given input and optional configuration options. If the input is a string, it creates a generation with the input as text and calls parseResult. If the input is a BaseMessage, it creates a generation with the input as a message and the content of the input as text, and then calls parseResult.
Parameters
- input: string | BaseMessage
  
  The input to the parser, which can be a string or a BaseMessage.
- Optional options: RunnableConfig
  
  Optional configuration options.
Returns Promise<string>
A promise of the parsed output.
Inherited from BaseTransformOutputParser.invoke
- Defined in langchain-core/src/output_parsers/base.ts:61

map

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

Returns Runnable<(string | BaseMessage)[], string[], RunnableConfig>
Inherited from BaseTransformOutputParser.map
- Defined in langchain-core/src/runnables/base.ts:168

parse

parse(text): Promise<string>
Parses a string output from an LLM call. This method is meant to be implemented by subclasses to define how a string output from an LLM should be parsed.
Parameters
- text: string
  
  The string output from an LLM call.
Returns Promise<string>
A promise of the parsed output.
Overrides BaseTransformOutputParser.parse
- Defined in langchain-core/src/output_parsers/string.ts:38

parseResult

parseResult(generations, callbacks?): Promise<string>
Parses the result of an LLM call. This method is meant to be implemented by subclasses to define how the output from the LLM should be parsed.
Parameters
- generations: Generation[] | ChatGeneration[]
  
  The generations from an LLM call.
- Optional callbacks: Callbacks
  
  Optional callbacks.
Returns Promise<string>
A promise of the parsed output.
Inherited from BaseTransformOutputParser.parseResult
- Defined in langchain-core/src/output_parsers/base.ts:97

parseResultWithPrompt

parseResultWithPrompt(generations, _prompt, callbacks?): Promise<string>
Parses the result of an LLM call with a given prompt. By default, it simply calls parseResult.
Parameters
- generations: Generation[] | ChatGeneration[]
  
  The generations from an LLM call.
- _prompt: BasePromptValueInterface
  
  The prompt used in the LLM call.
- Optional callbacks: Callbacks
  
  Optional callbacks.
Returns Promise<string>
A promise of the parsed output.
Inherited from BaseTransformOutputParser.parseResultWithPrompt
- Defined in langchain-core/src/output_parsers/base.ts:43

parseWithPrompt

parseWithPrompt(text, _prompt, callbacks?): Promise<string>
Parameters
- text: string
- _prompt: BasePromptValueInterface
- Optional callbacks: Callbacks
Returns Promise<string>
Inherited from BaseTransformOutputParser.parseWithPrompt
- Defined in langchain-core/src/output_parsers/base.ts:112

pick

pick(keys): Runnable<any, any, RunnableConfig>
Pick keys from the dict output of this runnable. Returns a new runnable.
Parameters
- keys: string | string[]
Returns Runnable<any, any, RunnableConfig>
Inherited from BaseTransformOutputParser.pick
- Defined in langchain-core/src/runnables/base.ts:568

pipe

pipe<NewRunOutput>(coerceable): Runnable<string | BaseMessage, Exclude<NewRunOutput, Error>, RunnableConfig>
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<string, NewRunOutput>
  
  A runnable, function, or object whose values are functions or runnables.
Returns Runnable<string | BaseMessage, Exclude<NewRunOutput, Error>, RunnableConfig>
A new runnable sequence.
Inherited from BaseTransformOutputParser.pipe
- Defined in langchain-core/src/runnables/base.ts:555

stream

stream(input, options?): Promise<IterableReadableStream<string>>
Stream output in chunks.
Parameters
- input: string | BaseMessage
- Optional options: Partial<RunnableConfig>
Returns Promise<IterableReadableStream<string>>
A readable stream that is also an iterable.
Inherited from BaseTransformOutputParser.stream
- Defined in langchain-core/src/runnables/base.ts:314

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: string | BaseMessage
- Optional options: Partial<RunnableConfig>
- Optional streamOptions: Omit<LogStreamCallbackHandlerInput, "autoClose">
Returns AsyncGenerator<RunLogPatch, any, unknown>
Inherited from BaseTransformOutputParser.streamLog
- Defined in langchain-core/src/runnables/base.ts:624

toJSON

toJSON(): Serialized
Returns Serialized
Inherited from BaseTransformOutputParser.toJSON
- Defined in langchain-core/src/load/serializable.ts:140

toJSONNotImplemented

toJSONNotImplemented(): SerializedNotImplemented
Returns SerializedNotImplemented
Inherited from BaseTransformOutputParser.toJSONNotImplemented
- Defined in langchain-core/src/load/serializable.ts:214

transform

transform(inputGenerator, options): AsyncGenerator<string, any, unknown>
Transforms an asynchronous generator of input into an asynchronous generator of parsed output.
Parameters
- inputGenerator: AsyncGenerator<string | BaseMessage, any, unknown>
  
  An asynchronous generator of input.
- options: BaseCallbackConfig
  
  A configuration object.
Returns AsyncGenerator<string, any, unknown>
An asynchronous generator of parsed output.
Inherited from BaseTransformOutputParser.transform
- Defined in langchain-core/src/output_parsers/transform.ts:49

withConfig

withConfig(config): RunnableBinding<string | BaseMessage, string, RunnableConfig>
Bind config to a Runnable, returning a new Runnable.
Parameters
- config: RunnableConfig
  
  New configuration parameters to attach to the new runnable.
Returns RunnableBinding<string | BaseMessage, string, RunnableConfig>
A new RunnableBinding with a config matching what's passed.
Inherited from BaseTransformOutputParser.withConfig
- Defined in langchain-core/src/runnables/base.ts:197

withFallbacks

withFallbacks(fields): RunnableWithFallbacks<string | BaseMessage, string>
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<string | BaseMessage, string, RunnableConfig>[];
  }
  - fallbacks: Runnable<string | BaseMessage, string, RunnableConfig>[]
    
    Other runnables to call if the runnable errors.
Returns RunnableWithFallbacks<string | BaseMessage, string>
A new RunnableWithFallbacks.
Inherited from BaseTransformOutputParser.withFallbacks
- Defined in langchain-core/src/runnables/base.ts:214

withListeners

withListeners(params): Runnable<string | BaseMessage, string, RunnableConfig>
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: RunnableConfig
      
      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: RunnableConfig
      
      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: RunnableConfig
      
      Returns void | Promise<void>
Returns Runnable<string | BaseMessage, string, RunnableConfig>
Inherited from BaseTransformOutputParser.withListeners
- Defined in langchain-core/src/runnables/base.ts:690

withRetry

withRetry(fields?): RunnableRetry<string | BaseMessage, string, RunnableConfig>
Add retry logic to an existing runnable.
Parameters
- Optional fields: {
  onFailedAttempt?: RunnableRetryFailedAttemptHandler;
  stopAfterAttempt?: number;
  }
  - Optional onFailedAttempt?: RunnableRetryFailedAttemptHandler
  - Optional stopAfterAttempt?: number
Returns RunnableRetry<string | BaseMessage, string, RunnableConfig>
A new RunnableRetry that, when invoked, will retry according to the parameters.
Inherited from BaseTransformOutputParser.withRetry
- Defined in langchain-core/src/runnables/base.ts:178

`Static` isRunnable

isRunnable(thing): thing is Runnable<any, any, RunnableConfig>
Parameters
- thing: any
Returns thing is Runnable<any, any, RunnableConfig>
Inherited from BaseTransformOutputParser.isRunnable
- Defined in langchain-core/src/runnables/base.ts:675

Class StringOutputParser

Example

Hierarchy

Index

Constructors

Properties

Methods

Constructors

constructor

Parameters

Optional kwargs: SerializedFields

Rest ..._args: never[]

Returns StringOutputParser

Properties

Optional name

Methods

assign

Parameters

mapping: RunnableMapLike<Record<string, unknown>, Record<string, unknown>>

Returns Runnable<any, any, RunnableConfig>

batch

Parameters

inputs: (string | BaseMessage)[]

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

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

Returns Promise<string[]>

Parameters

inputs: (string | BaseMessage)[]

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

Optional batchOptions: RunnableBatchOptions & { returnExceptions: true; }

Returns Promise<(string | Error)[]>

Parameters

inputs: (string | BaseMessage)[]

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

Optional batchOptions: RunnableBatchOptions

Returns Promise<(string | Error)[]>

bind

Parameters

kwargs: Partial<RunnableConfig>

Returns Runnable<string | BaseMessage, string, RunnableConfig>

getFormatInstructions

Returns string

Example

getName

Parameters

Optional suffix: string

Returns string

invoke

Parameters

input: string | BaseMessage

Optional options: RunnableConfig

Returns Promise<string>

map

Returns Runnable<(string | BaseMessage)[], string[], RunnableConfig>

parse

Parameters

text: string

Returns Promise<string>

parseResult

Parameters

generations: Generation[] | ChatGeneration[]

Optional callbacks: Callbacks

Returns Promise<string>

parseResultWithPrompt

Parameters

generations: Generation[] | ChatGeneration[]

_prompt: BasePromptValueInterface

Optional callbacks: Callbacks

Returns Promise<string>

parseWithPrompt

Parameters

text: string

_prompt: BasePromptValueInterface

Optional callbacks: Callbacks

Returns Promise<string>

pick

Parameters

keys: string | string[]

Returns Runnable<any, any, RunnableConfig>

pipe

`Optional` kwargs: SerializedFields

`Rest` ..._args: never[]

`Optional` name

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

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

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

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

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

`Optional` batchOptions: RunnableBatchOptions

`Optional` suffix: string

`Optional` options: RunnableConfig

`Optional` callbacks: Callbacks

`Optional` callbacks: Callbacks

`Optional` callbacks: Callbacks

`Optional` options: Partial<RunnableConfig>

`Optional` options: Partial<RunnableConfig>

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

fields: {
fallbacks: Runnable<string | BaseMessage, string, RunnableConfig>[];
}

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: RunnableConfig

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

`Optional` config: RunnableConfig

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

`Optional` config: RunnableConfig

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

`Optional` onFailedAttempt?: RunnableRetryFailedAttemptHandler

`Optional` stopAfterAttempt?: number

`Static` isRunnable