Dhalang 
Dhalang is a Ruby wrapper for Google's Puppeteer.
Features
- Generate PDFs from webpages
- Generate PDFs from HTML ( external images/stylesheets supported )
- Capture screenshots from webpages
- Scrape HTML from webpages
Installation
Add this line to your application's Gemfile:
gem 'Dhalang'
And then execute:
$ bundle update
Install puppeteer in your application's root directory:
$ npm install puppeteer
Dhalang and Puppeteer require Node ≥ 18 and Puppeteer ≥ 22
Usage
PDF of a website url
Dhalang::PDF.get_from_url("https://www.google.com")It is important to pass the complete url, leaving out https://, http:// or www. will result in an error.
PDF of a HTML string
Dhalang::PDF.get_from_html("<html><head></head><body><h1>examplestring</h1></body></html>") PNG screenshot of a website
Dhalang::Screenshot.get_from_url("https://www.google.com", :png) JPEG screenshot of a website
Dhalang::Screenshot.get_from_url("https://www.google.com", :jpeg) WEBP screenshot of a website
Dhalang::Screenshot.get_from_url("https://www.google.com", :webp) HTML of a website
Dhalang::Scraper.html("https://www.google.com") Above methods either return a string containing the PDF/JPEG/PNG/WEBP in binary or the scraped HTML.
Custom options
To override the default options that are set by Dhalang you can pass as last argument a hash with the custom options you want to set.
For example to set custom margins for PDFs:
Dhalang::PDF.get_from_url("https://www.google.com", {margin: { top: 100, right: 100, bottom: 100, left: 100}})For example to only take a screenshot of the visible part of the page:
Dhalang::Screenshot.get_from_url("https://www.google.com", :webp, {fullPage: false})A list of all possible PDF options that can be set, can be found at: https://github.com/puppeteer/puppeteer/blob/main/docs/api.md#pagepdfoptions
A list of all possible screenshot options that can be set, can be found at: https://github.com/puppeteer/puppeteer/blob/main/docs/api.md#pagescreenshotoptions
The default Puppeteer options contain the options
headerTemplateandfooterTemplate. Puppeteer expects these to be HTML strings. By default, the Dhalang gem passes all options as arguments in anode ...shell command. In case the HTML strings are too long they might surpass the maximum argument length of the host. For example, on Linux theMAX_ARG_LENis 128kB. Therefore, you can also pass the headers and footers as file path using the optionsheaderTemplateFileandfooterTemplateFile. These non-Puppeteer-options will be used to populate the Puppeteer-optionsheaderTemplateandfooterTemplate.For example:
Dhalang::PDF.get_from_url("https://www.google.com", {headerTemplateFile: '/tmp/header.html', footerTemplateFile: '/tmp/footer.html'})
Custom user options
You may want to change the way Dhalang interacts with Puppeteer in general. User options can be set by providing them in a hash as last argument to any calls you make to the library. Are you setting both custom PDF and user options? Then they should be passed as a single hash.
For example to set a custom navigation timeout:
Dhalang::Screenshot.get_from_url("https://www.google.com", :jpeg, {navigationTimeout: 20000}) Below table lists all possible configuration parameters that can be set:
| Key | Description | Default |
|---|---|---|
| navigationTimeout | Amount of milliseconds until Puppeteer while timeout when navigating to the given page | 10000 |
| printToPDFTimeout | Amount of milliseconds until Puppeteer while timeout when calling Page.printToPDF | 0 (unlimited) |
| navigationWaitForSelector | If set, Dhalang will wait for the specified selector to appear before creating the screenshot or PDF | None |
| navigationWaitForXPath | If set, Dhalang will wait for the specified XPath to appear before creating the screenshot or PDF | None |
| userAgent | User agent to send with the request | Default Puppeteer one |
| isHeadless | Indicates if Chromium should be launched headless | true |
| isAutoHeight | When set to true the height of generated PDFs will be based on the scrollHeight property of the document body | false |
| viewPort | Custom viewport to use for the request | Default Puppeteer one |
| httpAuthenticationCredentials | Custom HTTP authentication credentials to use for the request | None |
| chromeOptions | A array of options that can be passed to puppeteer in addition to the mandatory ['--no-sandbox', '--disable-setuid-sandbox']
|
[] |
Examples of using Dhalang
To return a PDF from a Rails controller you can do the following:
def example_controller_method
binary_pdf = Dhalang::PDF.get_from_url("https://www.google.com")
send_data(binary_pdf, filename: 'pdfofgoogle.pdf', type: 'application/pdf')
endTo return a screenshot from a Rails controller you can do the following:
def example_controller_method
binary_png = Dhalang::Screenshot.get_from_url("https://www.google.com", :png)
send_data(binary_png, filename: 'screenshotofgoogle.png', type: 'image/png')
end