Get Custom XMP Metadata

This guide will walk you through the example of getting custom XMP data from a pdf file.

Before you begin #

You should get your API key from your UniCloud account.

If this is your first time using UniPDF SDK, follow this guide to set up a local development environment.

Project setup #

Clone the project repository #

In your terminal, clone examples repository. It contains the Go code we will be using for this guide.

git clone https://github.com/unidoc/unipdf-examples.git

Navigate to the metadata folder in the unipdf-examples directory.

cd unipdf-examples/metadata

Configure environment variables #

Replace the UNIDOC_LICENSE_API_KEY with your API credentials from your UniCloud account.

Linux/Mac #

export UNIDOC_LICENSE_API_KEY=PUT_YOUR_API_KEY_HERE

Windows #

set UNIDOC_LICENSE_API_KEY=PUT_YOUR_API_KEY_HERE

How it works #

The following example code gets metadata from pdf file.

Line 3-15 imports the necessary unipdf packages.

The init function in lines 17-24 authenticates your request using the UNIDOC_LICENSE_API_KEY from the system environment.

The main function in lines 26-95 is an entry point to the program and contains all the code that gets the metadata from the pdf file. In the main function in lines 27-32 path to the input file is parsed from the command line argument. In lines 35-39 the time taken to finish running the program is measured. The input pdf file is read in lines 42-46. The XMP metadata is extracted in using reader.GetCatalogMetadata() in lines 49-52.

The lines 55-58 the PdfObjectStream represented by the metadata PdfObject is retrieved using core.GetStream(metadata). The XMP Document is loaded from the provided pdfObject stream in lines 61-64. The xmp.Document is loaded using xmpDoc.GetGoXmpDocument() in line 67. In lines 71-75 custom models are searched using the xmprights.FindModel(goXmpDoc) method. Finally the code in lines 76-94 tries to find and print some custom models such as certificate, Owners, Usage Terms and Web statement.

Run the code #

go run pdf_get_custom_xmp_metadata.go <input.pdf>