RunnableSequence<RunInput extends Object?, RunOutput extends Object?> class

A RunnableSequence allows you to run multiple Runnable objects sequentially, passing the output of the previous Runnable to the next one.

You can create a RunnableSequence in several ways:

• Calling Runnable.pipe method which takes another Runnable as an argument. E.g.:

final chain = promptTemplate.pipe(chatModel);

• Using the | operator. This is a convenience method that calls Runnable.pipe under the hood (note that it offers less type safety than Runnable.pipe because of Dart limitations). E.g.:

final chain = promptTemplate | chatModel;

• Using the Runnable.fromList static method with a list of Runnable, which will run in sequence when invoked. E.g.:

final chain = Runnable.fromList([promptTemplate, chatModel]);

When you call invoke on a RunnableSequence, it will invoke each Runnable in the sequence in order, passing the output of the previous Runnable to the next one. The output of the last Runnable in the sequence is returned.

You can think of RunnableSequence as the replacement for SequentialChain.

Example:

final openaiApiKey = Platform.environment['OPENAI_API_KEY'];
final model = ChatOpenAI(apiKey: openaiApiKey);

final promptTemplate = ChatPromptTemplate.fromTemplate(
  'Tell me a joke about {topic}',
);

// The following three chains are equivalent:
final chain1 = promptTemplate | model | StringOutputParser();
final chain2 = promptTemplate.pipe(model).pipe(StringOutputParser());
final chain3 = Runnable.fromList(
  [promptTemplate, model, StringOutputParser()],
);

final res = await chain1.invoke({'topic': 'bears'});
print(res);
// Why don't bears wear shoes? Because they have bear feet!

Inheritance

• Object
• Runnable<RunInput, RunnableOptions, RunOutput>
• RunnableSequence

Available extensions

• RunnableX

Constructors

RunnableSequence({required Runnable<RunInput, RunnableOptions, Object?> first, List<Runnable<Object?, RunnableOptions, Object?>> middle = const [], required Runnable<Object?, RunnableOptions, RunOutput> last})

A RunnableSequence allows you to run multiple Runnable objects sequentially, passing the output of the previous Runnable to the next one.

const

Properties

defaultOptions → RunnableOptions

The default options to use when invoking the Runnable.

final, inherited

first → Runnable<RunInput, RunnableOptions, Object?>

The first Runnable in the RunnableSequence.

final

hashCode → int

The hash code for this object.

no setter, inherited

last → Runnable<Object?, RunnableOptions, RunOutput>

The last Runnable in the RunnableSequence.

final

middle → List<Runnable<Object?, RunnableOptions, Object?>>

The middle Runnables in the RunnableSequence.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

steps → List<Runnable<Object?, RunnableOptions, Object?>>

Returns a list of all the Runnables in the RunnableSequence.

no setter

Methods

batch(List<RunInput> inputs, {List<RunnableOptions>? options}) → Future<List<RunOutput>>

Batches the invocation of the Runnable on the given inputs.

inherited

bind(RunnableOptions options) → RunnableBinding<RunInput, RunnableOptions, RunOutput>

Binds the Runnable to the given options.

inherited

close() → void

Cleans up any resources associated with it the Runnable.

override

getCompatibleOptions(RunnableOptions? options) → RunnableOptions?

Returns the given options if they are compatible with the Runnable, otherwise returns null.

inherited

invoke(RunInput input, {RunnableOptions? options}) → Future<RunOutput>

Invokes the RunnableSequence on the given input.

override

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

pipe<NewRunOutput extends Object?, NewCallOptions extends RunnableOptions>(Runnable<RunOutput, NewCallOptions, NewRunOutput> next) → RunnableSequence<RunInput, NewRunOutput>

Pipes the output of this RunnableSequence into another Runnable.

override

stream(RunInput input, {RunnableOptions? options}) → Stream<RunOutput>

Streams the output of invoking the Runnable on the given input.

override

streamFromInputStream(Stream<RunInput> inputStream, {RunnableOptions? options}) → Stream<RunOutput>

Streams the output of invoking the Runnable on the given inputStream.

override

toString() → String

A string representation of this object.

inherited

withFallbacks(List<Runnable<RunInput, RunnableOptions, RunOutput>> fallbacks) → RunnableWithFallback<RunInput, RunOutput>

Adds fallback runnables to be invoked if the primary runnable fails.

inherited

withRetry({int maxRetries = 3, FutureOr<bool> retryIf(Object e)?, List<Duration?>? delayDurations, bool addJitter = false}) → RunnableRetry<RunInput, RunOutput>

Adds retry logic to an existing runnable.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

operator |(Runnable<RunOutput, RunnableOptions, NewRunOutput> next) → RunnableSequence<RunInput, NewRunOutput>

Available on Runnable<RunInput, CallOptions, RunOutput>, provided by the RunnableX extension

Pipes the output of this Runnable into another Runnable.

Static Methods

from(List<Runnable<Object?, RunnableOptions, Object?>> runnables) → RunnableSequence<Object?, Object?>

Creates a RunnableSequence from a list of Runnables.