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Report Generation

For the purpose of everyday analysis of financial results, there's a way to create reports from JSON data and lay them out in several formats like PDF, DOCX, XLSX, PPTX, ODS, XML, CSV, etc. You can then combine it with your 4GL application to:

Obtain data from the database;
Compose this data file in JSON format;
Save the data file in your storage;
Call a script for report generation using a template and the data file;
Send a report to the client side.

Prerequisites

For generating a report, you have to prepare the following:

your database data in JSON format;
the template of an output document (use any XML-based document as a template - for instance, DOCX, ODT, ODS, XLSX, HTML, PPTX, ODP, custom XML files, etc.).

Creating a Report

To create a report, proceed as follows:

Step 1. Install LibreOffice on your machine: LibreOffice Installation.

Step 2. Install Node.JS of a version 14 or higher, and install npm:

sudo apt install npm

Step 3. Create a Node project:

npm init

Step 4. Add the Carbone dependency:

npm i carbone

Step 6. Create a script (for example, we will call the following script rg.mjs):

import carbone

from 'carbone';

import fs from 'fs';

const options = {

convertTo : 'pdf' //can be docx, txt, ...

}

const template = process.argv[2];

const data = JSON.parse(fs.readFileSync(process.argv[3], {encoding: 'utf8'}));

const output = process.argv[4];

const format = process.argv[5];

if (format) {

options.convertTo = format;

}

carbone.render(template, data, options, function(err, result){

if (err) {

return console.log(err);

}

fs.writeFileSync(output, result);

process.exit(); // to kill LibreOffice workers automatically

});

Step 7. Create a template and use it in the command for the report creation:

node rg.mjs <path_to_template> <path_to_data_file> <path_to_output_file> <optional_output_format>

Note: The output format defaults to PDF if not specified.