Utility Components

Component	Available Classes	Description
DocumentMerger	DocumentMerger	Concatenates multiple documents into a single one. Example usage: Creating summaries based on multiple documents.
Docs2Answers	Docs2Answers	Converts documents into answers. Example usage: When using REST API for document retrieval. REST API expects Answer as output, you can use Doc2Answer as the last node to convert the retrieved documents to answers.
JoinAnswers	JoinAnswers	Takes answers returned by multiple components and joins them in a single list of answers. Example usage: For running queries on different document types (for example, tables and text), where the documents are routed to different readers, and each reader returns a separate list of answers.
JoinDocuments	JoinDocuments	Takes documents returned by different components and joins them to form one list of documents. Example usage: In document retrieval pipelines, where there are different types of documents, each routed to a different retriever. Each retriever returns a separate list of documents, and you can join them into one list using JoinDocuments.
Shaper	Shaper	Currently functions mostly as PromptNode helper making sure the PromptNode input or output is correct. Example usage: In a question answering pipeline using PromptNode, where the PromptTemplate expects `questions` as input, while Haystack pipelines use `query`. You can use Shaper to rename `query` to `questions`.
Summarizer	TransformersSummarizer	Creates an overview of a document. Example usage: To get a glimpse of the documents the Retriever is returning.
TransformersImageToText	TransformersImageToText	Generates captions for images. Example usage: Automatically generating captions for a list of images that you can later use in your knowledge base.
Translator	TransformersTranslator	Translates text from one language into another. Example usage: Running searches on documents in other languages.