README
¶
go-wkhtmltopdf
Golang commandline wrapper for wkhtmltopdf
See http://wkhtmltopdf.org/index.html for wkhtmltopdf docs.
| ⚠ WARNING |
|---|
| wkhtmltopdf is no longer maintained and now archived on GitHub. See https://wkhtmltopdf.org/status.html |
| This go package is still maintained and will be for a while, but I recommend looking for alternatives for new projects. |
What and why
We needed a way to generate PDF documents from Go. These vary from invoices with highly customizable lay-outs to reports with tables, graphs and images. In our opinion the best way to do this was by using HTML/CSS templates as source for our PDFs. Using CSS print media types and millimeters instead of pixel units we can generate very acurate PDF documents using wkhtmltopdf.
go-wkhtmltopdf is a pure Golang wrapper around the wkhtmltopdf command line utility.
It has all options typed out as struct members which makes it very easy to use if you use an IDE with code completion and it has type safety for all options. For example you can set general options like
pdfg.Dpi.Set(600)
pdfg.NoCollate.Set(false)
pdfg.PageSize.Set(PageSizeA4)
pdfg.MarginBottom.Set(40)
The same goes for adding pages, settings page options, TOC options per page etc.
It takes care of setting the correct order of options as these can become very long with muliple pages where you have page and TOC options for each page.
Secondly it makes usage in server-type applications easier, every instance (PDF process) has its own output buffer which contains the PDF output and you can feed one input document from an io.Reader (using stdin in wkhtmltopdf). You can combine any number of external HTML documents (HTTP(S) links) with at most one HTML document from stdin and set options for each input document.
Note: You can also ignore the internal buffer and let wkhtmltopdf write directly to disk if required for large files, or use the SetOutput method to pass any io.Writer.
For us this is one of the easiest ways to generate PDF documents from Go(lang) and performance is very acceptable.
Installation
go get or use a Go dependency manager of your liking.
go get -u github.com/SebastiaanKlippert/go-wkhtmltopdf
go-wkhtmltopdf finds the path to wkhtmltopdf by
- first looking in the current dir
- looking in the PATH and PATHEXT environment dirs
- using the WKHTMLTOPDF_PATH environment dir
Warning: Running executables from the current path is no longer possible in Go 1.19, see https://pkg.go.dev/os/exec@master#hdr-Executables_in_the_current_directory
If you need to set your own wkhtmltopdf path or want to change it during execution, you can call SetPath().
Usage
See testfile wkhtmltopdf_test.go for more complex options, a common use case test is in simplesample_test.go
package wkhtmltopdf
import (
"fmt"
"log"
)
func ExampleNewPDFGenerator() {
// Create new PDF generator
pdfg, err := NewPDFGenerator()
if err != nil {
log.Fatal(err)
}
// Set global options
pdfg.Dpi.Set(300)
pdfg.Orientation.Set(OrientationLandscape)
pdfg.Grayscale.Set(true)
// Create a new input page from an URL
page := NewPage("https://godoc.org/github.com/SebastiaanKlippert/go-wkhtmltopdf")
// Set options for this page
page.FooterRight.Set("[page]")
page.FooterFontSize.Set(10)
page.Zoom.Set(0.95)
// Add to document
pdfg.AddPage(page)
// Create PDF document in internal buffer
err = pdfg.Create()
if err != nil {
log.Fatal(err)
}
// Write buffer contents to file on disk
err = pdfg.WriteFile("./simplesample.pdf")
if err != nil {
log.Fatal(err)
}
fmt.Println("Done")
// Output: Done
}
As mentioned before, you can provide one document from stdin, this is done by using a PageReader object as input to AddPage. This is best constructed with NewPageReader and will accept any io.Reader so this can be used with files from disk (os.File) or memory (bytes.Buffer) etc.
A simple example snippet:
html := "<html>Hi</html>"
pdfgen.AddPage(NewPageReader(strings.NewReader(html)))
Saving to and loading from JSON
The package now has the possibility to save the PDF Generator object as JSON and to create a new PDF Generator from a JSON file. All options and pages are saved in JSON, pages added using NewPageReader are read to memory before saving and then saved as Base64 encoded strings in the JSON file.
This is useful to prepare a PDF file and generate the actual PDF elsewhere, for example on AWS Lambda.
To create PDF Generator on the client, where wkhtmltopdf might not be present, function NewPDFPreparer can be used.
Use NewPDFPreparer to create a PDF Generator object on the client and NewPDFGeneratorFromJSON to reconstruct it on the server.
// Client code
pdfg := NewPDFPreparer()
htmlfile, err := ioutil.ReadFile("testdata/htmlsimple.html")
if err != nil {
log.Fatal(err)
}
pdfg.AddPage(NewPageReader(bytes.NewReader(htmlfile)))
pdfg.Dpi.Set(600)
// The contents of htmlsimple.html are saved as base64 string in the JSON file
jb, err := pdfg.ToJSON()
if err != nil {
log.Fatal(err)
}
// Server code
pdfgFromJSON, err := NewPDFGeneratorFromJSON(bytes.NewReader(jb))
if err != nil {
log.Fatal(err)
}
err = pdfgFromJSON.Create()
if err != nil {
log.Fatal(err)
}
For an example of running this in AWS Lambda see https://github.com/SebastiaanKlippert/go-wkhtmltopdf-lambda
Speed
The speed if pretty much determined by wkhtmltopdf itself, or if you use external source URLs, the time it takes to get and render the source HTML.
The go wrapper time is negligible with around 0.04ms for parsing an above average number of commandline options.
Benchmarks are included.
Documentation
¶
Overview ¶
Package wkhtmltopdf contains wrappers around the wkhtmltopdf commandline tool
Index ¶
- Constants
- func GetPath() string
- func SetPath(path string)
- type PDFGenerator
- func (pdfg *PDFGenerator) AddPage(p PageProvider)
- func (pdfg *PDFGenerator) ArgString() string
- func (pdfg *PDFGenerator) Args() []string
- func (pdfg *PDFGenerator) Buffer() *bytes.Buffer
- func (pdfg *PDFGenerator) Bytes() []byte
- func (pdfg *PDFGenerator) Create() error
- func (pdfg *PDFGenerator) CreateContext(ctx context.Context) error
- func (pdfg *PDFGenerator) ResetPages()
- func (pdfg *PDFGenerator) SetOutput(w io.Writer)
- func (pdfg *PDFGenerator) SetPages(p []PageProvider)
- func (pdfg *PDFGenerator) SetStderr(w io.Writer)
- func (pdfg *PDFGenerator) ToJSON() ([]byte, error)
- func (pdfg *PDFGenerator) WriteFile(filename string) error
- type Page
- type PageOptions
- type PageProvider
- type PageReader
Examples ¶
Constants ¶
const ( OrientationLandscape = "Landscape" // Landscape mode OrientationPortrait = "Portrait" // Portrait mode )
Constants for orientation modes
const ( PageSizeA0 = "A0" // 841 x 1189 mm PageSizeA1 = "A1" // 594 x 841 mm PageSizeA2 = "A2" // 420 x 594 mm PageSizeA3 = "A3" // 297 x 420 mm PageSizeA4 = "A4" // 210 x 297 mm, 8.26 PageSizeA5 = "A5" // 148 x 210 mm PageSizeA6 = "A6" // 105 x 148 mm PageSizeA7 = "A7" // 74 x 105 mm PageSizeA8 = "A8" // 52 x 74 mm PageSizeA9 = "A9" // 37 x 52 mm PageSizeB0 = "B0" // 1000 x 1414 mm PageSizeB1 = "B1" // 707 x 1000 mm PageSizeB10 = "B10" // 31 x 44 mm PageSizeB2 = "B2" // 500 x 707 mm PageSizeB3 = "B3" // 353 x 500 mm PageSizeB4 = "B4" // 250 x 353 mm PageSizeB5 = "B5" // 176 x 250 mm, 6.93 PageSizeB6 = "B6" // 125 x 176 mm PageSizeB7 = "B7" // 88 x 125 mm PageSizeB8 = "B8" // 62 x 88 mm PageSizeB9 = "B9" // 33 x 62 mm PageSizeC5E = "C5E" // 163 x 229 mm PageSizeComm10E = "Comm10E" // 105 x 241 mm, U.S. Common 10 Envelope PageSizeCustom = "Custom" // Unknown, or a user defined size. PageSizeDLE = "DLE" // 110 x 220 mm PageSizeExecutive = "Executive" // 7.5 x 10 inches, 190.5 x 254 mm PageSizeFolio = "Folio" // 210 x 330 mm PageSizeLedger = "Ledger" // 431.8 x 279.4 mm PageSizeLegal = "Legal" // 8.5 x 14 inches, 215.9 x 355.6 mm PageSizeLetter = "Letter" // 8.5 x 11 inches, 215.9 x 279.4 mm PageSizeTabloid = "Tabloid" // 279.4 x 431.8 mm )
Constants for page sizes
Variables ¶
This section is empty.
Functions ¶
Types ¶
type PDFGenerator ¶
type PDFGenerator struct {
Cover cover
TOC toc
OutputFile string //filename to write to, default empty (writes to internal buffer)
// contains filtered or unexported fields
}
PDFGenerator is the main wkhtmltopdf struct, always use NewPDFGenerator to obtain a new PDFGenerator struct
func NewPDFGenerator ¶
func NewPDFGenerator() (*PDFGenerator, error)
NewPDFGenerator returns a new PDFGenerator struct with all options created and checks if wkhtmltopdf can be found on the system
Example ¶
// Create new PDF generator
pdfg, err := NewPDFGenerator()
if err != nil {
log.Fatal(err)
}
// Set global options
pdfg.Dpi.Set(300)
pdfg.Orientation.Set(OrientationLandscape)
pdfg.Grayscale.Set(true)
// Create a new input page from an URL
page := NewPage("https://godoc.org/github.com/SebastiaanKlippert/go-wkhtmltopdf")
// Set options for this page
page.FooterRight.Set("[page]")
page.FooterFontSize.Set(10)
page.Zoom.Set(0.95)
// Add to document
pdfg.AddPage(page)
// Create PDF document in internal buffer
err = pdfg.Create()
if err != nil {
log.Fatal(err)
}
// Write buffer contents to file on disk
err = pdfg.WriteFile("./simplesample.pdf")
if err != nil {
log.Fatal(err)
}
fmt.Println("Done")
Output: Done
func NewPDFGeneratorFromJSON ¶ added in v1.2.0
func NewPDFGeneratorFromJSON(jsonReader io.Reader) (*PDFGenerator, error)
NewPDFGeneratorFromJSON creates a new PDFGenerator and restores all the settings and pages from a JSON byte slice which should be created using PDFGenerator.ToJSON().
Example ¶
const html = `<!doctype html><html><head><title>WKHTMLTOPDF TEST</title></head><body>HELLO PDF</body></html>`
// Client code
pdfg := NewPDFPreparer()
pdfg.AddPage(NewPageReader(strings.NewReader(html)))
pdfg.Dpi.Set(600)
// The html string is also saved as base64 string in the JSON file
jsonBytes, err := pdfg.ToJSON()
if err != nil {
log.Fatal(err)
}
// The JSON can be saved, uploaded, etc.
// Server code, create a new PDF generator from JSON, also looks for the wkhtmltopdf executable
pdfgFromJSON, err := NewPDFGeneratorFromJSON(bytes.NewReader(jsonBytes))
if err != nil {
log.Fatal(err)
}
// Create the PDF
err = pdfgFromJSON.Create()
if err != nil {
log.Fatal(err)
}
// Use the PDF
fmt.Printf("PDF size %d bytes", pdfgFromJSON.Buffer().Len())
Output:
func NewPDFPreparer ¶ added in v1.2.0
func NewPDFPreparer() *PDFGenerator
NewPDFPreparer returns a PDFGenerator object without looking for the wkhtmltopdf executable file. This is useful to prepare a PDF file that is generated elsewhere and you just want to save the config as JSON. Note that Create() can not be called on this object unless you call SetPath yourself.
func (*PDFGenerator) AddPage ¶
func (pdfg *PDFGenerator) AddPage(p PageProvider)
AddPage adds a new input page to the document. A page is an input HTML page, it can span multiple pages in the output document. It is a Page when read from file or URL or a PageReader when read from memory.
func (*PDFGenerator) ArgString ¶
func (pdfg *PDFGenerator) ArgString() string
ArgString returns Args as a single string
func (*PDFGenerator) Args ¶
func (pdfg *PDFGenerator) Args() []string
Args returns the commandline arguments as a string slice
func (*PDFGenerator) Buffer ¶
func (pdfg *PDFGenerator) Buffer() *bytes.Buffer
Buffer returns the embedded output buffer used if OutputFile is empty
func (*PDFGenerator) Bytes ¶
func (pdfg *PDFGenerator) Bytes() []byte
Bytes returns the output byte slice from the output buffer used if OutputFile is empty
func (*PDFGenerator) Create ¶
func (pdfg *PDFGenerator) Create() error
Create creates the PDF document and stores it in the internal buffer if no error is returned
func (*PDFGenerator) CreateContext ¶ added in v1.7.0
func (pdfg *PDFGenerator) CreateContext(ctx context.Context) error
CreateContext is Create with a context passed to exec.CommandContext when calling wkhtmltopdf
func (*PDFGenerator) ResetPages ¶ added in v1.4.1
func (pdfg *PDFGenerator) ResetPages()
ResetPages drops all pages previously added by AddPage or SetPages. This allows reuse of current instance of PDFGenerator with all of it's configuration preserved.
func (*PDFGenerator) SetOutput ¶ added in v1.3.0
func (pdfg *PDFGenerator) SetOutput(w io.Writer)
SetOutput sets the output to write the PDF to, when this method is called, the internal buffer will not be used, so the Bytes(), Buffer() and WriteFile() methods will not work.
func (*PDFGenerator) SetPages ¶
func (pdfg *PDFGenerator) SetPages(p []PageProvider)
SetPages resets all pages
func (*PDFGenerator) SetStderr ¶ added in v1.5.0
func (pdfg *PDFGenerator) SetStderr(w io.Writer)
SetStderr sets the output writer for Stderr when running the wkhtmltopdf command. You only need to call this when you want to print the output of wkhtmltopdf (like the progress messages in verbose mode). If not called, or if w is nil, the output of Stderr is kept in an internal buffer and returned as error message if there was an error when calling wkhtmltopdf.
func (*PDFGenerator) ToJSON ¶ added in v1.2.0
func (pdfg *PDFGenerator) ToJSON() ([]byte, error)
ToJSON creates JSON of the complete representation of the PDFGenerator. It also saves all pages. For a PageReader page, the content is stored as a Base64 string in the JSON.
func (*PDFGenerator) WriteFile ¶
func (pdfg *PDFGenerator) WriteFile(filename string) error
WriteFile writes the contents of the output buffer to a file
type Page ¶
type Page struct {
Input string
PageOptions
}
Page is the input struct for each page
type PageOptions ¶
type PageOptions struct {
// contains filtered or unexported fields
}
PageOptions are options for each input page
func NewPageOptions ¶
func NewPageOptions() PageOptions
NewPageOptions returns a new PageOptions struct with all options
type PageProvider ¶ added in v1.6.1
PageProvider is the interface which provides a single input page. Implemented by Page and PageReader.
type PageReader ¶
type PageReader struct {
Input io.Reader
PageOptions
}
PageReader is one input page (a HTML document) that is read from an io.Reader You can add only one Page from a reader
func NewPageReader ¶
func NewPageReader(input io.Reader) *PageReader
NewPageReader creates a new PageReader from an io.Reader
func (*PageReader) Args ¶
func (pr *PageReader) Args() []string
Args returns the argument slice and is part of the page interface
func (*PageReader) InputFile ¶
func (pr *PageReader) InputFile() string
InputFile returns the input string and is part of the page interface
func (*PageReader) Reader ¶
func (pr *PageReader) Reader() io.Reader
Reader returns the io.Reader and is part of the page interface
Source Files