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Create PDF From JSON

Creates a new PDF document or updates an existing one using a JSON definition file that describes the PDF structure and content.

Common Properties​

  • Name - The custom name of the node.
  • Color - The custom color of the node.
  • Delay Before (sec) - Waits in seconds before executing the node.
  • Delay After (sec) - Waits in seconds after executing node.
  • Continue On Error - Automation will continue regardless of any error. The default value is false.
info

If the ContinueOnError property is true, no error is caught when the project is executed, even if a Catch node is used.

Inputs​

  • JSON Path - Path to the JSON file containing the PDF definition.

Options​

  • In PDF Path - Input PDF path for updating an existing PDF with the JSON definition. Optional.
  • Out PDF Path - Output path where the created or updated PDF file will be saved. Optional.
note

At least one of In PDF Path or Out PDF Path must be provided:

  • If only Out PDF Path is provided: Creates a new PDF from JSON
  • If only In PDF Path is provided: Updates the existing PDF in place
  • If both are provided: Reads the input PDF and saves the result to the output path

Output​

This node does not produce any output variables. The result is saved to the specified PDF file.

How It Works​

The Create PDF From JSON node generates or modifies PDF documents based on a JSON definition. When executed, the node:

  1. Validates the JSON path and reads the JSON definition
  2. Determines the operation mode based on provided paths
  3. If updating: Opens the existing PDF file
  4. Applies the JSON definition to create or modify the PDF structure
  5. Saves the result to the appropriate output path

Operation Modes​

In PDF PathOut PDF PathAction
EmptyProvidedCreate new PDF and save to output path
ProvidedEmptyUpdate existing PDF in place
ProvidedProvidedRead input PDF, apply changes, save to output path

Use Cases​

  • PDF Generation: Create PDFs dynamically from structured data
  • Template Processing: Generate documents from JSON-based templates
  • PDF Modification: Update existing PDFs with new content or structure
  • Batch Document Creation: Generate multiple PDFs from different JSON files
  • Form Creation: Define PDF form structures programmatically

JSON Definition Format​

The JSON file defines the PDF structure including pages, content, and properties. Consult the pdfcpu library documentation for the complete JSON schema specification.

Example basic structure:

{
  "pages": [
    {
      "content": "Page content here",
      "properties": {
        "size": "A4"
      }
    }
  ]
}

Error Handling​

The node will return specific errors in the following cases:

  • Empty or invalid JSON path
  • JSON file not found or invalid JSON format
  • Neither In PDF Path nor Out PDF Path is provided
  • Invalid PDF path (when In PDF Path is provided)
  • Input PDF file not found (when In PDF Path is provided)
  • Invalid JSON definition structure
  • Insufficient permissions to read input files or write output file

Usage Notes​

  • The JSON definition follows the pdfcpu library schema
  • When updating an existing PDF, the original file is modified according to the JSON definition
  • For creating new PDFs, ensure the JSON contains all required PDF elements
  • The output directory must exist before saving the PDF
  • Complex PDF structures may require detailed JSON definitions
  • Validate your JSON structure before processing to avoid errors

Tips for Effective Use​

  • Start Simple: Begin with basic JSON definitions and gradually add complexity
  • Validate JSON: Use a JSON validator to check syntax before processing
  • Backup Originals: When updating existing PDFs, always specify an output path to preserve originals
  • Reference Documentation: Consult pdfcpu documentation for detailed JSON schema
  • Testing: Test JSON definitions with sample files first
  • Error Handling: Enable Continue On Error when batch processing multiple files
  • Export To JSON: Extract form data from existing PDFs
  • Fill From JSON: Fill PDF form fields with JSON data