TextLanguageRouter

Route text strings to different pipeline branches based on their detected language.

Key Features

• Detects the language of a text string using langdetect.
• Routes text to a named output matching the detected language.
• Supports multiple languages configured at initialization.
• Routes text that doesn't match any configured language to an unmatched output.

Configuration

1. Drag the TextLanguageRouter component onto the canvas from the Component Library.
2. Click on the component to open the configuration panel.
3. On the General tab:
   • Set Languages to the list of ISO 639-1 language codes you want to route (for example, ["en", "de", "fr"]). If not specified, defaults to ["en"]. See the supported languages in the langdetect documentation.

Connections

TextLanguageRouter receives a single text string. For each language you configure, it creates a named output connection (for example, en or de). Text that doesn't match any configured language is routed to the unmatched output. Connect each language output to the appropriate downstream component.

Routing Documents by Language

To route documents (not text strings) by language, use DocumentLanguageClassifier followed by MetadataRouter.

Source Code

To check this component's source code, open text_language_router.py in the Haystack repository.

Usage Examples

Basic Configuration

  TextLanguageRouter:
    type: components.routers.text_language_router.TextLanguageRouter
    init_parameters: {}

To route documents by language instead of raw text, use DocumentLanguageClassifier followed by MetadataRouter.

components:
  TextLanguageRouter:
    type: components.routers.text_language_router.TextLanguageRouter
    init_parameters:

Parameters

Inputs

Parameter	Type	Description
text	str	A text string to route.

Outputs

Parameter	Type	Description
(per language code)	str	The text routed to the output matching the detected language.
unmatched	str	The text when its language doesn't match any configured language.

Init Parameters

These are the parameters you can configure in Pipeline Builder:

Parameter	Type	Default	Description
languages	Optional[List[str]]	None	A list of ISO 639-1 language codes. See the supported languages in the langdetect documentation. If not specified, defaults to ["en"].

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
text	str		A text string to route.