Generating PDF from json and json-schema - json

Question

We're currently using Alpaca Forms to generate forms which we use to edit data stored in json for our application. We're now looking for a way to, server side, generate PDF documents, using json-schema and the json.
Ideally this would be using C#, but frankly, we really could use any language, as long as we can put it behind a web service.
Basically, it would be Alpaca, but the output would be a PDF report, which could contain a cover page and other document friendly features. It would also use the "title" and "description" fields from the json-schema.
Any ideas other than trying to roll our own? I'd rather not PDF library, since most seem to not be that document oriented.

Answer 1

wkhtmltopdf is my personal favourite way of doing this. You should be able to convert your JSON schema into HTML, and then render it via that.

Answer 2

If you are using Node: You can use Chromium's (Opensource Chrome browser) Puppeteer to launch a headless browser, server side, which can generate a PDF.
const puppeteer = require('puppeteer');
const browser = await puppeteer.launch({headless: true});
const page = await browser.newPage();
page.setContent('<h1>My PDF!</h1>');
const myPdf = page.pdf();
See https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#pagepdfoptions for more PDF options when generating from Puppeteer
I haven't tested the code above but that's the basics of what I'm using to generate PDF's
npm i puppeteer will be needed :)

Answer 3

It may be difficult (impossible?) to convert the Alpaca Forms JSON automatically into something that lays out pages the way you want. For example, does the Alpaca JSON provide enough information to determine page size, orientation, headers, footers, numbering location and style etc?
Docmosis may be useful to you (please note I work for Docmosis). You would layout your PDF in a word processor document and call Docmosis to merge it with your JSON data to create the PDF. The fields in your template drive the data extraction so you can put <> into your template and the title will be extracted from the JSON. In the case of Alpaca it looks like the title might be keyed under "schema" in the JSON, so you would use <> in a Docmosis template. Page layout and styles come from the template. The quickest way to test this as a candidate solution is to create a cloud account, upload a template and call the REST API with your JSON to create the document. If that does what you need you have the cloud or on-premise options.
I hope that helps.

Answer 4

if ideally for you is C#, then to generate PDF from json you need:
Parse JSON to some C# collection;
Loop through collection and write data into PDF-table;
Save file as PDF.
For this purpose you will need some PDF-creating library.
Here is an example, how to implement it in C# using PDFFlow library:
Prepare class for storing data:
public sealed class ReportData
{
public string name { get; set; }
public string surname { get; set; }
public string address { get; set; }
}
Read data from JSON into collection:
string jsonFilePath = Path.Combine(SubfolderName, JSONFileName);
List<ReportData> jsonData = JsonSerializer.Deserialize<List<ReportData>>(File.ReadAllText(jsonFile));
Create PDF document and add table to it:
using Gehtsoft.PDFFlow.Builder;
var section = DocumentBuilder.New().AddSection();
var table = section.AddTable();
table
.AddColumnToTable("Name", 150)
.AddColumnToTable("Surname", 250)
.AddColumn("Address", 300);
Loop through collection and add data to a table:
foreach(var rowData in jsonData)
{
var row = table.AddRow();
row
.AddCellToRow(rowData.name)
.AddCellToRow(rowData.surname)
.AddCell(rowData.address);
}
Save document to PDF file:
section
.ToDocument()
.Build("Result.PDF");
To compile this code you need to add reference to PDFFlow library to your project.
Hope, this will help.
Here is a fully working example of PDF contract generation, demonstrating how to work with JSON as a data source: contract example