StringJoiner

Join strings from different components to a single list of strings.

Basic Information

• Type: haystack.components.joiners.string_joiner.StringJoiner
• Components it can connect with:
  • Any component that outputs strings, such as generators or extractors.

Inputs

Parameter	Type	Default	Description
strings	Variadic[str]		strings from different components

Outputs

Parameter	Type	Default	Description
strings	List[str]		Merged list of strings.

Overview

StringJoiner collects strings from different components and joins them into a single list of strings. This component is useful when you need to aggregate text outputs from multiple sources in a pipeline.

Usage Example

This example shows a pipeline that creates multiple prompt strings and joins them together.

components:
  PromptBuilder1:
    type: haystack.components.builders.prompt_builder.PromptBuilder
    init_parameters:
      template: "Question 1: {{ query }}"
  PromptBuilder2:
    type: haystack.components.builders.prompt_builder.PromptBuilder
    init_parameters:
      template: "Question 2: {{ query }}"
  PromptBuilder3:
    type: haystack.components.builders.prompt_builder.PromptBuilder
    init_parameters:
      template: "Question 3: {{ query }}"
  StringJoiner:
    type: haystack.components.joiners.string_joiner.StringJoiner
    init_parameters: {}

connections:
- sender: PromptBuilder1.prompt
  receiver: StringJoiner.strings
- sender: PromptBuilder2.prompt
  receiver: StringJoiner.strings
- sender: PromptBuilder3.prompt
  receiver: StringJoiner.strings

max_runs_per_component: 100

metadata: {}

inputs:
  query:
  - PromptBuilder1.query
  - PromptBuilder2.query
  - PromptBuilder3.query

Parameters

Init Parameters

These are the parameters you can configure in Pipeline Builder:

Parameter	Type	Default	Description

Run Method Parameters

These are the parameters you can configure for the component's run() method. This means you can pass these parameters at query time through the API, in Playground, or when running a job. For details, see Modify Pipeline Parameters at Query Time.

Parameter	Type	Default	Description
strings	Variadic[str]		strings from different components