FastGPT/document/content/docs/introduction/guide/dashboard/workflow/loop.en.mdx

---
title: Batch Processing
description: FastGPT Batch Processing node overview and usage
---

## Node Overview

The **Batch Processing** node was introduced in FastGPT V4.8.11. It allows workflows to iterate over array-type input data, processing one element at a time and automatically executing subsequent nodes until the entire array is processed.

This node is inspired by loop structures in programming languages, presented in a visual format.

![Batch Processing node](/imgs/fastgpt-loop-node.png)

> In programming terms, nodes are like functions or API endpoints -- each one is a **step**. By connecting multiple nodes together, you build a step-by-step process that produces the final AI output.

The **Batch Processing** node is essentially a function whose job is to automate repeated execution of a specific workflow.

## Core Features

1. **Array Batch Processing**
   - Accepts array-type data input
   - Automatically iterates through array elements
   - Maintains processing order
   - Supports parallel processing for performance optimization

2. **Automatic Iteration**
   - Automatically triggers downstream nodes
   - Supports conditional termination
   - Supports loop counting
   - Maintains execution context

3. **Works with Other Nodes**
   - AI Chat nodes
   - HTTP Request nodes
   - Content Extraction nodes
   - Conditional nodes

## Use Cases

The **Batch Processing** node extends workflow capabilities through automation, enabling FastGPT to handle batch tasks and complex data processing pipelines. It significantly improves efficiency when processing large-scale data or scenarios requiring multiple iterations.

The **Batch Processing** node is ideal for:

1. **Batch Data Processing**
   - Batch text translation
   - Batch document summarization
   - Batch content generation

2. **Data Pipeline Processing**
   - Analyzing search results one by one
   - Processing Knowledge Base retrieval results individually
   - Processing array data from HTTP responses item by item

3. **Recursive or Iterative Tasks**
   - Long text segmented processing
   - Multi-round content refinement
   - Chained data processing

## Usage

### Input Parameters

The **Batch Processing** node requires two core inputs:

1. **Array (Required)**: An array-type input, which can be:
   - String array (`Array<string>`)
   - Number array (`Array<number>`)
   - Boolean array (`Array<boolean>`)
   - Object array (`Array<object>`)

2. **Loop Body (Required)**: Defines the node flow executed in each iteration:
   - Loop Body Start: Marks where the loop begins
   - Loop Body End: Marks where the loop ends, with an optional output variable

### Loop Body Configuration

![Loop body configuration](/imgs/fastgpt-loop-node-config.webp)

1. Inside the loop body, you can add any type of node:
   - AI Chat node
   - HTTP Request node
   - Content Extraction node
   - Text Processing node, etc.

2. Loop Body End node configuration:
   - Select the output variable from the dropdown
   - This variable is collected as the current iteration's result
   - Results from all iterations form a new array as the final output

## Examples

### Batch Processing an Array

Suppose you have an array of texts that each need AI processing. This is the most basic and common use case.

#### Steps

1. Prepare the input array

   ![Prepare input array](/imgs/fastgpt-loop-node-example-1.png)

   Use a Code Execution node to create a test array:

   ```javascript
   const texts = [
     "这是第一段文本",
     "这是第二段文本",
     "这是第三段文本"
   ];
   return { textArray: texts };
   ```

2. Configure the Batch Processing node

   ![Configure Batch Processing node](/imgs/fastgpt-loop-node-example-2.png)

   - Array input: Select the `textArray` output from the previous Code Execution node.
   - Add an AI Chat node inside the loop body to process each text. Set the prompt to: `Please translate this text to English`.
   - Add a Specified Reply node to output the translated text.
   - Set the Loop Body End node's output variable to the AI reply content.

#### Execution Flow

![Execution flow](/imgs/fastgpt-loop-node-example-3.png)

1. The Code Execution node runs and generates the test array
2. The Batch Processing node receives the array and begins iteration
3. For each element:
   - The AI Chat node processes the current element
   - The Specified Reply node outputs the translated text
   - The Loop Body End node collects the result
4. After all elements are processed, the result array is output

### Long Text Translation

When translating long texts, you often face these challenges:

- Text length exceeds LLM token limits
- Translation style must remain consistent
- Context coherence must be maintained
- Translation quality may need multiple refinement passes

The **Batch Processing** node handles these well.

#### Steps

1. Text preprocessing and segmentation

   ![Text preprocessing and segmentation](/imgs/fastgpt-loop-node-example-4.png)

   Use a Code Execution node for text segmentation:

   ```javascript
   const MAX_HEADING_LENGTH = 7; // Max heading length
   const MAX_HEADING_CONTENT_LENGTH = 200; // Max heading content length
   const MAX_HEADING_UNDERLINE_LENGTH = 200; // Max heading underline length
   const MAX_HTML_HEADING_ATTRIBUTES_LENGTH = 100; // Max HTML heading attributes length
   const MAX_LIST_ITEM_LENGTH = 200; // Max list item length
   const MAX_NESTED_LIST_ITEMS = 6; // Max nested list items
   const MAX_LIST_INDENT_SPACES = 7; // Max list indent spaces
   const MAX_BLOCKQUOTE_LINE_LENGTH = 200; // Max blockquote line length
   const MAX_BLOCKQUOTE_LINES = 15; // Max blockquote lines
   const MAX_CODE_BLOCK_LENGTH = 1500; // Max code block length
   const MAX_CODE_LANGUAGE_LENGTH = 20; // Max code language length
   const MAX_INDENTED_CODE_LINES = 20; // Max indented code lines
   const MAX_TABLE_CELL_LENGTH = 200; // Max table cell length
   const MAX_TABLE_ROWS = 20; // Max table rows
   const MAX_HTML_TABLE_LENGTH = 2000; // Max HTML table length
   const MIN_HORIZONTAL_RULE_LENGTH = 3; // Min horizontal rule length
   const MAX_SENTENCE_LENGTH = 400; // Max sentence length
   const MAX_QUOTED_TEXT_LENGTH = 300; // Max quoted text length
   const MAX_PARENTHETICAL_CONTENT_LENGTH = 200; // Max parenthetical content length
   const MAX_NESTED_PARENTHESES = 5; // Max nested parentheses
   const MAX_MATH_INLINE_LENGTH = 100; // Max inline math length
   const MAX_MATH_BLOCK_LENGTH = 500; // Max math block length
   const MAX_PARAGRAPH_LENGTH = 1000; // Max paragraph length
   const MAX_STANDALONE_LINE_LENGTH = 800; // Max standalone line length
   const MAX_HTML_TAG_ATTRIBUTES_LENGTH = 100; // Max HTML tag attributes length
   const MAX_HTML_TAG_CONTENT_LENGTH = 1000; // Max HTML tag content length
   const LOOKAHEAD_RANGE = 100;  // Lookahead range for sentence boundaries

   const AVOID_AT_START = `[\\s\\]})>,']`; // Characters to avoid at start
   const PUNCTUATION = `[.!?…]|\\.{3}|[\\u2026\\u2047-\\u2049]|[\\p{Emoji_Presentation}\\p{Extended_Pictographic}]`; // Punctuation
   const QUOTE_END = `(?:'(?=\`)|''(?=\`\`))`; // Quote end
   const SENTENCE_END = `(?:${PUNCTUATION}(?<!${AVOID_AT_START}(?=${PUNCTUATION}))|${QUOTE_END})(?=\\S|$)`; // Sentence end
   const SENTENCE_BOUNDARY = `(?:${SENTENCE_END}|(?=[\\r\\n]|$))`; // Sentence boundary
   const LOOKAHEAD_PATTERN = `(?:(?!${SENTENCE_END}).){1,${LOOKAHEAD_RANGE}}${SENTENCE_END}`; // Lookahead pattern
   const NOT_PUNCTUATION_SPACE = `(?!${PUNCTUATION}\\s)`; // Non-punctuation space
   const SENTENCE_PATTERN = `${NOT_PUNCTUATION_SPACE}(?:[^\\r\\n]{1,{MAX_LENGTH}}${SENTENCE_BOUNDARY}|[^\\r\\n]{1,{MAX_LENGTH}}(?=${PUNCTUATION}|$   {QUOTE_END})(?:${LOOKAHEAD_PATTERN})?)${AVOID_AT_START}*`; // Sentence pattern

   const regex = new RegExp(
     "(" +
     // 1. Headings (Setext-style, Markdown, and HTML-style, with length constraints)
     `(?:^(?:[#*=-]{1,${MAX_HEADING_LENGTH}}|\\w[^\\r\\n]{0,${MAX_HEADING_CONTENT_LENGTH}}\\r?\\n[-=]{2,${MAX_HEADING_UNDERLINE_LENGTH}}|<h[1-6][^>]   {0,${MAX_HTML_HEADING_ATTRIBUTES_LENGTH}}>)[^\\r\\n]{1,${MAX_HEADING_CONTENT_LENGTH}}(?:</h[1-6]>)?(?:\\r?\\n|$))` +
     "|" +
     // New pattern for citations
     `(?:\\[[0-9]+\\][^\\r\\n]{1,${MAX_STANDALONE_LINE_LENGTH}})` +
     "|" +
     // 2. List items (bulleted, numbered, lettered, or task lists, including nested, up to three levels, with length constraints)
     `(?:(?:^|\\r?\\n)[ \\t]{0,3}(?:[-*+•]|\\d{1,3}\\.\\w\\.|\\[[ xX]\\])[ \\t]+${SENTENCE_PATTERN.replace(/{MAX_LENGTH}/g, String   (MAX_LIST_ITEM_LENGTH))}` +
     `(?:(?:\\r?\\n[ \\t]{2,5}(?:[-*+•]|\\d{1,3}\\.\\w\\.|\\[[ xX]\\])[ \\t]+${SENTENCE_PATTERN.replace(/{MAX_LENGTH}/g, String   (MAX_LIST_ITEM_LENGTH))}){0,${MAX_NESTED_LIST_ITEMS}}` +
     `(?:\\r?\\n[ \\t]{4,${MAX_LIST_INDENT_SPACES}}(?:[-*+•]|\\d{1,3}\\.\\w\\.|\\[[ xX]\\])[ \\t]+${SENTENCE_PATTERN.replace(/{MAX_LENGTH}/g, String   (MAX_LIST_ITEM_LENGTH))}){0,${MAX_NESTED_LIST_ITEMS}})?)` +
     "|" +
     // 3. Block quotes (including nested quotes and citations, up to three levels, with length constraints)
     `(?:(?:^>(?:>|\\s{2,}){0,2}${SENTENCE_PATTERN.replace(/{MAX_LENGTH}/g, String(MAX_BLOCKQUOTE_LINE_LENGTH))}\\r?\\n?){1,$   {MAX_BLOCKQUOTE_LINES}})` +
     "|" +
     // 4. Code blocks (fenced, indented, or HTML pre/code tags, with length constraints)
     `(?:(?:^|\\r?\\n)(?:\`\`\`|~~~)(?:\\w{0,${MAX_CODE_LANGUAGE_LENGTH}})?\\r?\\n[\\s\\S]{0,${MAX_CODE_BLOCK_LENGTH}}?(?:\`\`\`|~~~)\\r?\\n?` +
     `|(?:(?:^|\\r?\\n)(?: {4}|\\t)[^\\r\\n]{0,${MAX_LIST_ITEM_LENGTH}}(?:\\r?\\n(?: {4}|\\t)[^\\r\\n]{0,${MAX_LIST_ITEM_LENGTH}}){0,$   {MAX_INDENTED_CODE_LINES}}\\r?\\n?)` +
     `|(?:<pre>(?:<code>)?[\\s\\S]{0,${MAX_CODE_BLOCK_LENGTH}}?(?:</code>)?</pre>))` +
     "|" +
     // 5. Tables (Markdown, grid tables, and HTML tables, with length constraints)
     `(?:(?:^|\\r?\\n)(?:\\|[^\\r\\n]{0,${MAX_TABLE_CELL_LENGTH}}\\|(?:\\r?\\n\\|[-:]{1,${MAX_TABLE_CELL_LENGTH}}\\|){0,1}(?:\\r?\\n\\|[^\\r\\n]{0,$   {MAX_TABLE_CELL_LENGTH}}\\|){0,${MAX_TABLE_ROWS}}` +
     `|<table>[\\s\\S]{0,${MAX_HTML_TABLE_LENGTH}}?</table>))` +
     "|" +
     // 6. Horizontal rules (Markdown and HTML hr tag)
     `(?:^(?:[-*_]){${MIN_HORIZONTAL_RULE_LENGTH},}\\s*$|<hr\\s*/?>)` +
     "|" +
     // 10. Standalone lines or phrases (including single-line blocks and HTML elements, with length constraints)
     `(?!${AVOID_AT_START})(?:^(?:<[a-zA-Z][^>]{0,${MAX_HTML_TAG_ATTRIBUTES_LENGTH}}>)?${SENTENCE_PATTERN.replace(/{MAX_LENGTH}/g, String   (MAX_STANDALONE_LINE_LENGTH))}(?:</[a-zA-Z]+>)?(?:\\r?\\n|$))` +
     "|" +
     // 7. Sentences or phrases ending with punctuation (including ellipsis and Unicode punctuation)
     `(?!${AVOID_AT_START})${SENTENCE_PATTERN.replace(/{MAX_LENGTH}/g, String(MAX_SENTENCE_LENGTH))}` +
     "|" +
     // 8. Quoted text, parenthetical phrases, or bracketed content (with length constraints)
     "(?:" +
     `(?<!\\w)\"\"\"[^\"]{0,${MAX_QUOTED_TEXT_LENGTH}}\"\"\"(?!\\w)` +
     `|(?<!\\w)(?:['\"\`'"])[^\\r\\n]{0,${MAX_QUOTED_TEXT_LENGTH}}\\1(?!\\w)` +
     `|(?<!\\w)\`[^\\r\\n]{0,${MAX_QUOTED_TEXT_LENGTH}}'(?!\\w)` +
     `|(?<!\\w)\`\`[^\\r\\n]{0,${MAX_QUOTED_TEXT_LENGTH}}''(?!\\w)` +
     `|\\([^\\r\\n()]{0,${MAX_PARENTHETICAL_CONTENT_LENGTH}}(?:\\([^\\r\\n()]{0,${MAX_PARENTHETICAL_CONTENT_LENGTH}}\\)[^\\r\\n()]{0,$   {MAX_PARENTHETICAL_CONTENT_LENGTH}}){0,${MAX_NESTED_PARENTHESES}}\\)` +
     `|\\[[^\\r\\n\\[\\]]{0,${MAX_PARENTHETICAL_CONTENT_LENGTH}}(?:\\[[^\\r\\n\\[\\]]{0,${MAX_PARENTHETICAL_CONTENT_LENGTH}}\\][^\\r\\n\\[\\]]{0,$   {MAX_PARENTHETICAL_CONTENT_LENGTH}}){0,${MAX_NESTED_PARENTHESES}}\\]` +
     `|\\$[^\\r\\n$]{0,${MAX_MATH_INLINE_LENGTH}}\\$` +
     `|\`[^\`\\r\\n]{0,${MAX_MATH_INLINE_LENGTH}}\`` +
     ")" +
     "|" +
     // 9. Paragraphs (with length constraints)
     `(?!${AVOID_AT_START})(?:(?:^|\\r?\\n\\r?\\n)(?:<p>)?${SENTENCE_PATTERN.replace(/{MAX_LENGTH}/g, String(MAX_PARAGRAPH_LENGTH))}(?:</p>)?(?=\\r?   \\n\\r?\\n|$))` +
     "|" +
     // 11. HTML-like tags and their content (including self-closing tags and attributes, with length constraints)
     `(?:<[a-zA-Z][^>]{0,${MAX_HTML_TAG_ATTRIBUTES_LENGTH}}(?:>[\\s\\S]{0,${MAX_HTML_TAG_CONTENT_LENGTH}}?</[a-zA-Z]+>|\\s*/>))` +
     "|" +
     // 12. LaTeX-style math expressions (inline and block, with length constraints)
     `(?:(?:\\$\\$[\\s\\S]{0,${MAX_MATH_BLOCK_LENGTH}}?\\$\\$)|(?:\\$[^\\$\\r\\n]{0,${MAX_MATH_INLINE_LENGTH}}\\$))` +
     "|" +
     // 14. Fallback for any remaining content (with length constraints)
     `(?!${AVOID_AT_START})${SENTENCE_PATTERN.replace(/{MAX_LENGTH}/g, String(MAX_STANDALONE_LINE_LENGTH))}` +
     ")",
     "gmu"
   );

   function main({text}){
     const chunks = [];
     let currentChunk = '';
     const tokens = countToken(text)

     const matches = text.match(regex);
     if (matches) {
       matches.forEach((match) => {
         if (currentChunk.length + match.length <= 1000) {
           currentChunk += match;
         } else {
           if (currentChunk) {
             chunks.push(currentChunk);
           }
           currentChunk = match;
         }
       });
       if (currentChunk) {
         chunks.push(currentChunk);
       }
     }

     return {chunks, tokens};
   }
   ```

   This uses [a powerful regex open-sourced by Jina AI](https://x.com/JinaAI_/status/1823756993108304135) that leverages all possible boundary clues and heuristics for precise text splitting.

2. Configure the Batch Processing node

   ![Configure Batch Processing node](/imgs/fastgpt-loop-node-example-5.png)

   - Array input: Select the `chunks` output from the previous Code Execution node.
   - Add a Code Execution node inside the loop body to format the source text.
   - Add a Search Glossary node to look up proper nouns from a terminology Knowledge Base before translation.
   - Add an AI Chat node using CoT (Chain of Thought) to have the LLM explicitly generate a reasoning chain showing the complete translation thought process.
   - Add a Code Execution node to extract the final translation result from the AI Chat node's last round.
   - Add a Specified Reply node to output the translated text.
   - Set the Loop Body End node's output variable to the `result` output from the Extract Translation Text node.