HTML to PDF in Golang

This page describes how to use our cloud-based API to convert web pages and HTML to PDF in Golang. The API is user-friendly and can be integrated into your application with just a few lines of code. For general information about the converter, please visit our HTML to PDF API page.

Installation

The Golang API client library provides easy access to the Pdfcrowd API. No third-party libraries are required.

Install the client library from Github
go get github.com/pdfcrowd/pdfcrowd-go

We also offer other installation options.

Authentication

The credentials to access the API are your Pdfcrowd username and the API key. You can try out the API without registering using the following demo credentials:

  • Username: demo
  • API key: ce544b6ea52a5621fb9d55f8b542d14d

To get your personal API credentials, you can start a free API trial or buy the API license.

Getting Started

You can enter a web page or upload an HTML file to get a PDF output preview in our API playground. The playground allows you to interactively play with the API settings and autogenerates corresponding Golang code that you can copy and paste to your application.

Or you can choose from the examples below and adapt the code to your needs.

API Method Reference

Refer to the HTML to PDF Golang Reference for a description of all API methods.

Code Examples

Here are a few Golang examples to get you started quickly with the API. See more examples. 

package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
)

func main() {
    // create the API client instance
    client := pdfcrowd.NewHtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // run the conversion and write the result to a file
    err := client.ConvertUrlToFile("http://www.example.com", "example.pdf")

    // check for the conversion error
    handleError(err)
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // rethrow or handle the exception
        panic(err.Error())
    }
}
package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
)

func main() {
    // create the API client instance
    client := pdfcrowd.NewHtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // run the conversion and write the result to a file
    err := client.ConvertFileToFile("/path/to/MyLayout.html", "MyLayout.pdf")

    // check for the conversion error
    handleError(err)
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // rethrow or handle the exception
        panic(err.Error())
    }
}
package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
)

func main() {
    // create the API client instance
    client := pdfcrowd.NewHtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // run the conversion and write the result to a file
    err := client.ConvertStringToFile("<html><body><h1>Hello World!</h1></body></html>", "HelloWorld.pdf")

    // check for the conversion error
    handleError(err)
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // rethrow or handle the exception
        panic(err.Error())
    }
}

API Playground Examples

The API can be easily integrated into your environment. You can have our interactive API Playground autogenerate the integration code for you:

Common Customizations

The API lets you convert a web page, a local HTML file, or a string containing HTML. The result of the conversion can be stored to a local file, to a stream object or to a variable. See the conversion input section for more details.

The best way to start with the API is to choose one of the examples and once you get it working, you can further customize the code. You can find the most common customizations in the table below.

Page size Change the page size with setPageSize or setPageDimensions . Pass -1 to setPageHeight to get a single page PDF containing the whole document.
Page orientation Change the page orientation to landscape with setOrientation.
Page margins Adjust the page margins with setPageMargins.
Headers and footers Add headers and footers with setHeaderHtml and setFooterHtml. Set the height with setFooterHeight and setHeaderHeight.
You can learn more in this tutorial.
Zoom Scale the HTML contents with setScaleFactor.
Hide or remove elements You can use the following classes in your HTML code to hide or remove elements from the output:
  • pdfcrowd-remove - sets display:none!important on the element
  • pdfcrowd-hide - sets visibility:hidden!important on the element
Learn about other options.
Use @media print You can switch to the print version of the page (if it exists) with setUsePrintMedia.
Force page break You can force a page break with
<div style="page-break-before:always"></div>
Avoid page break You can avoid a page break inside an element with the following CSS
th, td, img { page-break-inside:avoid }
Run custom JavaScript You can use setOnLoadJavascript or setCustomJavascript to alter the HTML contents with a custom JavaScript. In addition to the standard browser APIs, the custom JavaScript code can use helper functions from our JavaScript library .
Custom CSS styling You can alter CSS styling used during conversion with a custom JavaScript or using the pdfcrowd-body CSS class, which is automatically set on the HTML <body> element. You can, for example, set the H1 height to 48px by adding the following line to your CSS:
.pdfcrowd-body h1 { font-size: 48px; }
Add PDF signature You can create PDF containing a digital signature field. Such PDF can be digitally signed in, for example, Adobe Acrobat or Preview. Learn more in Create Digital Signature in PDF .
Fillable PDF form You can create fillable PDF containing interactive fields and buttons. Learn more in Create Fillable PDF Form.

Template Rendering

The API enables rendering of HTML templates. The template syntax is based on the Jinja template rendering engine.

The most common constructs are:

  • Data rendering: Invoice: {{ invoice.number }}
  • For loop: {% for invoice in invoices %} ... {% endfor %}
  • If statement: {% if invoice.total > 100 %} ... {% endif %}
  • Data filter: {{ invoice.to.first_name|capitalize }}

The supported input data formats are JSON, XML, CSV and YAML. The data can be uploaded from a file or from a string variable.

Supported template filters: capitalize, center, default, escape, first, forceescape, format, indent, join, last, length, list, lower, replace, reverse, safe, slice, sort, string, striptags, title, trim, truncate, unique, upper, wordcount, wordwrap.

See template rendering examples.

Error Handling

It is recommended that you implement error handling to catch errors that the API may return, see the example code below. A list of status codes and their description can be found here. 

// call the API 

    // print error
    os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))

    // print just error code
    os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error Code: %v\n", why.getCode()))

    // print just error message
    os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error Message: %v\n", why.getMessage()))

    // or handle the error in your way

Troubleshooting