Class PromptTemplate<RunInput, PartialVariableName>

Schema to represent a basic prompt for an LLM.

Example

import { PromptTemplate } from "langchain/prompts";

const prompt = new PromptTemplate({
  inputVariables: ["foo"],
  template: "Say {foo}",
});

Type Parameters

RunInput extends InputValues = any
PartialVariableName extends string = any

Hierarchy

BaseStringPromptTemplate<RunInput, PartialVariableName>
- PromptTemplate

Implements

PromptTemplateInput<RunInput, PartialVariableName>

Constructors

constructor

new PromptTemplate<RunInput, PartialVariableName>(input): PromptTemplate<RunInput, PartialVariableName>
Type Parameters
- RunInput extends InputValues = any
- PartialVariableName extends string = any
Parameters
- input: PromptTemplateInput<RunInput, PartialVariableName>
Returns PromptTemplate<RunInput, PartialVariableName>
Overrides BaseStringPromptTemplate.constructor
- Defined in docs/api_refs/langchain/src/prompts/prompt.ts:117

Properties

PromptValueReturnType

PromptValueReturnType: StringPromptValue

inputVariables

inputVariables: Extract<keyof RunInput, string>[]

A list of variable names the prompt template expects

partialVariables

partialVariables: PartialValues<PartialVariableName>

Partial variables

template

template: string

The prompt template

templateFormat

templateFormat: "f-string" = "f-string"

The format of the prompt template. Options are 'f-string'

Default Value

'f-string'

validateTemplate

validateTemplate: boolean = true

Whether or not to try validating the template on initialization

Default Value

true

`Optional` outputParser

outputParser?: BaseOutputParser<unknown>

How to parse the output of calling an LLM on this formatted prompt

Methods

batch

batch(inputs, options?, batchOptions?): Promise<StringPromptValue[]>
Default implementation of batch, which calls invoke N times. Subclasses should override this method if they can batch more efficiently.
Parameters
- inputs: RunInput[]
  
  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<StringPromptValue[]>
An array of RunOutputs, or mixed RunOutputs and errors if batchOptions.returnExceptions is set
Inherited from BaseStringPromptTemplate.batch
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:159
batch(inputs, options?, batchOptions?): Promise<(Error | StringPromptValue)[]>
Parameters
- inputs: RunInput[]
- Optional options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]
- Optional batchOptions: RunnableBatchOptions & {
  returnExceptions: true;
  }
Returns Promise<(Error | StringPromptValue)[]>
Inherited from BaseStringPromptTemplate.batch
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:165
batch(inputs, options?, batchOptions?): Promise<(Error | StringPromptValue)[]>
Parameters
- inputs: RunInput[]
- Optional options: Partial<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]
- Optional batchOptions: RunnableBatchOptions
Returns Promise<(Error | StringPromptValue)[]>
Inherited from BaseStringPromptTemplate.batch
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:171

bind

bind(kwargs): Runnable<RunInput, StringPromptValue, BaseCallbackConfig>
Bind arguments to a Runnable, returning a new Runnable.
Parameters
- kwargs: Partial<BaseCallbackConfig>
Returns Runnable<RunInput, StringPromptValue, BaseCallbackConfig>
A new RunnableBinding that, when invoked, will apply the bound args.
Inherited from BaseStringPromptTemplate.bind
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:67

format

format(values): Promise<string>
Formats the prompt template with the provided values.
Parameters
- values: TypedPromptInputValues<RunInput>
  
  The values to be used to format the prompt template.
Returns Promise<string>
A promise that resolves to a string which is the formatted prompt.
Overrides BaseStringPromptTemplate.format
- Defined in docs/api_refs/langchain/src/prompts/prompt.ts:146

formatPromptValue

formatPromptValue(values): Promise<StringPromptValue>
Formats the prompt given the input values and returns a formatted prompt value.
Parameters
- values: TypedPromptInputValues<RunInput>
  
  The input values to format the prompt.
Returns Promise<StringPromptValue>
A Promise that resolves to a formatted prompt value.
Inherited from BaseStringPromptTemplate.formatPromptValue
- Defined in docs/api_refs/langchain/src/prompts/base.ts:253

invoke

invoke(input, options?): Promise<StringPromptValue>
Invokes the prompt template with the given input and options.
Parameters
- input: RunInput
  
  The input to invoke the prompt template with.
- Optional options: BaseCallbackConfig
  
  Optional configuration for the callback.
Returns Promise<StringPromptValue>
A Promise that resolves to the output of the prompt template.
Inherited from BaseStringPromptTemplate.invoke
- Defined in docs/api_refs/langchain/src/prompts/base.ts:154

map

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

Returns Runnable<RunInput[], StringPromptValue[], BaseCallbackConfig>
Inherited from BaseStringPromptTemplate.map
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:78

mergePartialAndUserVariables

mergePartialAndUserVariables(userVariables): Promise<InputValues<PartialVariableName | Extract<keyof RunInput, string>>>
Merges partial variables and user variables.
Parameters
- userVariables: TypedPromptInputValues<RunInput>
  
  The user variables to merge with the partial variables.
Returns Promise<InputValues<PartialVariableName | Extract<keyof RunInput, string>>>
A Promise that resolves to an object containing the merged variables.
Inherited from BaseStringPromptTemplate.mergePartialAndUserVariables
- Defined in docs/api_refs/langchain/src/prompts/base.ts:125

partial

partial<NewPartialVariableName>(values): Promise<PromptTemplate<InputValues<Exclude<Extract<keyof RunInput, string>, NewPartialVariableName>>, any>>
Partially applies values to the prompt template.
Type Parameters
- NewPartialVariableName extends string
Parameters
- values: PartialValues<NewPartialVariableName>
  
  The values to be partially applied to the prompt template.
Returns Promise<PromptTemplate<InputValues<Exclude<Extract<keyof RunInput, string>, NewPartialVariableName>>, any>>
A new instance of PromptTemplate with the partially applied values.
Overrides BaseStringPromptTemplate.partial
- Defined in docs/api_refs/langchain/src/prompts/prompt.ts:219

pipe

pipe<NewRunOutput>(coerceable): RunnableSequence<RunInput, 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<StringPromptValue, NewRunOutput>
  
  A runnable, function, or object whose values are functions or runnables.
Returns RunnableSequence<RunInput, Exclude<NewRunOutput, Error>>
A new runnable sequence.
Inherited from BaseStringPromptTemplate.pipe
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:461

serialize

serialize(): SerializedPromptTemplate
Return a json-like object representing this prompt template.

Returns SerializedPromptTemplate

Deprecated
Overrides BaseStringPromptTemplate.serialize
- Defined in docs/api_refs/langchain/src/prompts/prompt.ts:241

stream

stream(input, options?): Promise<IterableReadableStream<StringPromptValue>>
Stream output in chunks.
Parameters
- input: RunInput
- Optional options: Partial<BaseCallbackConfig>
Returns Promise<IterableReadableStream<StringPromptValue>>
A readable stream that is also an iterable.
Inherited from BaseStringPromptTemplate.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: RunInput
- Optional options: Partial<BaseCallbackConfig>
- Optional streamOptions: Omit<LogStreamCallbackHandlerInput, "autoClose">
Returns AsyncGenerator<RunLogPatch, any, unknown>
Inherited from BaseStringPromptTemplate.streamLog
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:507

toJSON

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

toJSONNotImplemented

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

transform

transform(generator, options): AsyncGenerator<StringPromptValue, 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<RunInput, any, unknown>
- options: Partial<BaseCallbackConfig>
Returns AsyncGenerator<StringPromptValue, any, unknown>
Inherited from BaseStringPromptTemplate.transform
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:478

withConfig

withConfig(config): RunnableBinding<RunInput, StringPromptValue, BaseCallbackConfig>
Bind config to a Runnable, returning a new Runnable.
Parameters
- config: BaseCallbackConfig
  
  New configuration parameters to attach to the new runnable.
Returns RunnableBinding<RunInput, StringPromptValue, BaseCallbackConfig>
A new RunnableBinding with a config matching what's passed.
Inherited from BaseStringPromptTemplate.withConfig
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:107

withFallbacks

withFallbacks(fields): RunnableWithFallbacks<RunInput, StringPromptValue>
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<RunInput, StringPromptValue, BaseCallbackConfig>[];
  }
  - fallbacks: Runnable<RunInput, StringPromptValue, BaseCallbackConfig>[]
    
    Other runnables to call if the runnable errors.
Returns RunnableWithFallbacks<RunInput, StringPromptValue>
A new RunnableWithFallbacks.
Inherited from BaseStringPromptTemplate.withFallbacks
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:124

withRetry

withRetry(fields?): RunnableRetry<RunInput, StringPromptValue, BaseCallbackConfig>
Add retry logic to an existing runnable.
Parameters
- Optional fields: {
  onFailedAttempt?: RunnableRetryFailedAttemptHandler;
  stopAfterAttempt?: number;
  }
  - Optional onFailedAttempt?: RunnableRetryFailedAttemptHandler
  - Optional stopAfterAttempt?: number
Returns RunnableRetry<RunInput, StringPromptValue, BaseCallbackConfig>
A new RunnableRetry that, when invoked, will retry according to the parameters.
Inherited from BaseStringPromptTemplate.withRetry
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:88

`Static` deserialize

deserialize(data): Promise<PromptTemplate<any, any>>
Parameters
- data: SerializedPromptTemplate
Returns Promise<PromptTemplate<any, any>>

Deprecated
Load a prompt template from a json-like object describing it.

Remarks
Deserializing needs to be async because templates (e.g. FewShotPromptTemplate) can reference remote resources that we read asynchronously with a web request.
Overrides BaseStringPromptTemplate.deserialize
- Defined in docs/api_refs/langchain/src/prompts/prompt.ts:255

`Static` fromExamples

fromExamples(examples, suffix, inputVariables, exampleSeparator?, prefix?): PromptTemplate<any, any>
Take examples in list format with prefix and suffix to create a prompt.

Intended to be used a a way to dynamically create a prompt from examples.
Parameters
- examples: string[]
  
  List of examples to use in the prompt.
- suffix: string
  
  String to go after the list of examples. Should generally set up the user's input.
- inputVariables: string[]
  
  A list of variable names the final prompt template will expect
- exampleSeparator: string = "\n\n"
  
  The separator to use in between examples
- prefix: string = ""
  
  String that should go before any examples. Generally includes examples.
Returns PromptTemplate<any, any>
The final prompt template generated.
- Defined in docs/api_refs/langchain/src/prompts/prompt.ts:164

`Static` fromTemplate

fromTemplate<RunInput, T>(template, __namedParameters?): PromptTemplate<RunInput extends Symbol
? ParamsFromFString<T>
: RunInput, any>
Load prompt template from a template f-string
Type Parameters
- RunInput extends InputValues = Symbol
- T extends string = string
Parameters
- template: T
- __namedParameters: Omit<PromptTemplateInput<RunInput, string>, "template" | "inputVariables"> = {}
Returns PromptTemplate<RunInput extends Symbol
? ParamsFromFString<T>
: RunInput, any>
- Defined in docs/api_refs/langchain/src/prompts/prompt.ts:181

`Static` isRunnable

isRunnable(thing): thing is Runnable<any, any, BaseCallbackConfig>
Parameters
- thing: any
Returns thing is Runnable<any, any, BaseCallbackConfig>
Inherited from BaseStringPromptTemplate.isRunnable
- Defined in docs/api_refs/langchain/src/schema/runnable/base.ts:557

Class PromptTemplate<RunInput, PartialVariableName>

Example

Type Parameters

RunInput extends InputValues = any

PartialVariableName extends string = any

Hierarchy

Implements

Index

Constructors

Properties

Methods

Constructors

constructor

Type Parameters

RunInput extends InputValues = any

PartialVariableName extends string = any

Parameters

input: PromptTemplateInput<RunInput, PartialVariableName>

Returns PromptTemplate<RunInput, PartialVariableName>

Properties

PromptValueReturnType

inputVariables

partialVariables

template

templateFormat

Default Value

validateTemplate

Default Value

Optional outputParser

Methods

batch

Parameters

inputs: RunInput[]

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

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

Returns Promise<StringPromptValue[]>

Parameters

inputs: RunInput[]

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

Optional batchOptions: RunnableBatchOptions & { returnExceptions: true; }

Returns Promise<(Error | StringPromptValue)[]>

Parameters

inputs: RunInput[]

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

Optional batchOptions: RunnableBatchOptions

Returns Promise<(Error | StringPromptValue)[]>

bind

Parameters

kwargs: Partial<BaseCallbackConfig>

Returns Runnable<RunInput, StringPromptValue, BaseCallbackConfig>

format

Parameters

values: TypedPromptInputValues<RunInput>

Returns Promise<string>

formatPromptValue

Parameters

values: TypedPromptInputValues<RunInput>

Returns Promise<StringPromptValue>

invoke

Parameters

input: RunInput

Optional options: BaseCallbackConfig

Returns Promise<StringPromptValue>

map

Returns Runnable<RunInput[], StringPromptValue[], BaseCallbackConfig>

mergePartialAndUserVariables

Parameters

userVariables: TypedPromptInputValues<RunInput>

Returns Promise<InputValues<PartialVariableName | Extract<keyof RunInput, string>>>

partial

Type Parameters

NewPartialVariableName extends string

Parameters

values: PartialValues<NewPartialVariableName>

Returns Promise<PromptTemplate<InputValues<Exclude<Extract<keyof RunInput, string>, NewPartialVariableName>>, any>>

pipe

Type Parameters

NewRunOutput

Parameters

coerceable: RunnableLike<StringPromptValue, NewRunOutput>

`Optional` outputParser

`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

`Optional` options: BaseCallbackConfig

`Optional` options: Partial<BaseCallbackConfig>

`Optional` options: Partial<BaseCallbackConfig>

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

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

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

`Optional` onFailedAttempt?: RunnableRetryFailedAttemptHandler

`Optional` stopAfterAttempt?: number

`Static` deserialize

`Static` fromExamples

`Static` fromTemplate

Returns PromptTemplate<RunInput extends Symbol
? ParamsFromFString<T>
: RunInput, any>

`Static` isRunnable