Get XML Metadata

In this guide getting the XML metadata of root catalog for PDF files will be demonstrated.

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

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.





How it works

The following example code gets metadata from pdf file.

The import section defined in lines 13-24 imports necessary unipdf packages and other go libraries. The init function in lines 26-33 loads UNIDOC_LICENSE_API_KEY from system environment and authenticates your request.

The main function is defined in lines 35-52 and is used to get the XML pdf metadata. In lines 36-42 the input files is parsed from the command line argument. The loop in lines 43-51 iterates through each input file and prints XML metadata for each pdf document using printXMLMetadataForPdf.

The printXMLMetadataForPdf function defined in lines 54-98 is used to get the XML metadata and print it to standard output. In this function in lines 55-64 a new model.PdfReader is created using the input file given as an argument of the function.

In lines 66-69 the root catalog is obtained using the function getRootCatalog. The code in lines 72-84 gets the XML metadata. Then it is decoded into xmp metadata format in lines 87-92 using xmlDecoder.Decode(&xmp). Finally the metadata is printed using xmp.print() in line 95.

The getRootCatalog function defined in lines 102-123 returns the root catalog PdfObjectDictionary type. In lines 127-138 the function resolve which is used to resolve reference objects is defined. In lines 143-151 the xmpMetadata type is defined which is used to hold the xmp metadata. Two methods of this xmpMetadata type, namely keyValMap() and print() are defined in lines 155-180.

Run the code

go run pdf_metadata_get_xml.go <input1.pdf> <input2.pdf> ...

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