PDF to PDF API - Go SDK

Join multiple PDF files in Go using the Pdfcrowd API v2. The API is easy to use and the integration takes only a couple of lines of code.

Installation

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

You can learn more about other install options here.

Authentication

Authentication is needed in order to use the Pdfcrowd API. The credentials used for accessing the API are your Pdfcrowd username and the API key. You can sign up for the Pdfcrowd API here.

Examples

Join 4 local PDF files together to a PDF file
package main

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

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("your_username", "your_apikey")

    // configure the conversion
    client.AddPdfFile("/path/to/cover.pdf")
    client.AddPdfFile("/path/to/proposal.pdf")
    client.AddPdfFile("/path/to/price.pdf")
    client.AddPdfFile("/path/to/contact.pdf")

    // run the conversion and write the result to a file
    err := client.ConvertToFile("offer.pdf")

    // check for a 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))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
Join 4 local PDF files together to in-memory PDF
package main

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

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("your_username", "your_apikey")

    // configure the conversion
    client.AddPdfFile("/path/to/cover.pdf")
    client.AddPdfFile("/path/to/proposal.pdf")
    client.AddPdfFile("/path/to/price.pdf")
    client.AddPdfFile("/path/to/contact.pdf")

    // create output file for conversion result
    outputFile, err := os.Create("offer.pdf")

    // check for a file creation error
    handleError(err)

    // close the output file
    defer outputFile.Close()

    // run the conversion and store the result into a pdf variable
    pdf, err := client.Convert()

    // check for a conversion error
    handleError(err)

    // write the pdf into the output file
    _, err = outputFile.Write(pdf)

    // check for a file write 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))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
Join 4 local PDF files together and write the resulting PDF to an output stream
package main

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

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("your_username", "your_apikey")

    // configure the conversion
    client.AddPdfFile("/path/to/cover.pdf")
    client.AddPdfFile("/path/to/proposal.pdf")
    client.AddPdfFile("/path/to/price.pdf")
    client.AddPdfFile("/path/to/contact.pdf")

    // create output stream for conversion result
    outputStream, err := os.Create("offer.pdf")

    // check for a file creation error
    handleError(err)

    // close the output stream
    defer outputStream.Close()

    // run the conversion and write the result into the output stream
    err = client.ConvertToStream(outputStream)

    // check for a 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))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
Join 4 in-memory PDFs together to a PDF file
package main

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

func readFile(fileName string) []byte {
    content, err := ioutil.ReadFile(fileName)
    handleError(err)
    return content
}

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("your_username", "your_apikey")

    // configure the conversion
    client.AddPdfRawData(readFile("/path/to/cover.pdf"))
    client.AddPdfRawData(readFile("/path/to/proposal.pdf"))
    client.AddPdfRawData(readFile("/path/to/price.pdf"))
    client.AddPdfRawData(readFile("/path/to/contact.pdf"))

    // run the conversion and write the result to a file
    err := client.ConvertToFile("offer.pdf")

    // check for a 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))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
Join 2 in-memory PDFs together with 2 local PDF files to a PDF file
package main

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

func readFile(fileName string) []byte {
    content, err := ioutil.ReadFile(fileName)
    handleError(err)
    return content
}

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("your_username", "your_apikey")

    // configure the conversion
    client.AddPdfRawData(readFile("/path/to/cover.pdf"))
    client.AddPdfFile("/path/to/proposal.pdf")
    client.AddPdfRawData(readFile("/path/to/price.pdf"))
    client.AddPdfFile("/path/to/contact.pdf")

    // run the conversion and write the result to a file
    err := client.ConvertToFile("offer.pdf")

    // check for a 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))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
Get info about the current conversion
package main

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

func readFile(fileName string) []byte {
    content, err := ioutil.ReadFile(fileName)
    handleError(err)
    return content
}

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("your_username", "your_apikey")

    // configure the conversion
    client.SetDebugLog(true)
    client.AddPdfRawData(readFile("/path/to/cover.pdf"))
    client.AddPdfRawData(readFile("/path/to/proposal.pdf"))

    // run the conversion and write the result to a file
    err := client.ConvertToFile("offer.pdf")

    // check for a conversion error
    handleError(err)
    
    // print URL to the debug log
    fmt.Println("Debug log url:", client.GetDebugLogUrl())
    
    // print the number of available conversion credits in your account
    fmt.Println("Remaining credit count:", client.GetRemainingCreditCount())
    
    // print the number of credits consumed by the conversion
    fmt.Println("Consumed credit count:", client.GetConsumedCreditCount())
    
    // print the unique ID of the conversion
    fmt.Println("Job id:", client.GetJobId())
    
    // print the total number of pages in the output document
    fmt.Println("Page count:", client.GetPageCount())
    
    // print the size of the output in bytes
    fmt.Println("Output size:", client.GetOutputSize())
}

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))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}

Tips & Tricks

API Reference - class PdfToPdfClient

Conversion from PDF to PDF.

Constructor

func NewPdfToPdfClient(userName string, apiKey string) PdfToPdfClient
Constructor for the Pdfcrowd API client.
Parameter Description Default
userName
Your username at Pdfcrowd.
apiKey
Your API key.

 

PDF Manipulation

func (client *PdfToPdfClient) SetAction(action string) *PdfToPdfClient
Specifies the action to be performed on the input PDFs.
Parameter Description Default
action
Allowed values:
  • join
    Concatenate input PDFs into a single one.
  • shuffle
    Collate pages from input PDFs into a single one, take one page at a time from each input PDF. This is useful when combining two scanned documents containing odd and even pages.
join
Returns
  • PdfToPdfClient - The converter object.
func (client *PdfToPdfClient) Convert() ([]byte, error)
Perform an action on the input files.
Returns
  • []byte - Byte array containing the output PDF.
func (client *PdfToPdfClient) ConvertToStream(outStream io.Writer) error
Perform an action on the input files and write the output PDF to an output stream.
Parameter Description Default
outStream
The output stream that will contain the output PDF.
func (client *PdfToPdfClient) ConvertToFile(filePath string) error
Perform an action on the input files and write the output PDF to a file.
Parameter Description Default
filePath
The output file path.
The string must not be empty.
func (client *PdfToPdfClient) AddPdfFile(filePath string) *PdfToPdfClient
Add a PDF file to the list of the input PDFs.
Parameter Description Default
filePath
The file path to a local PDF file.
The file must exist and not be empty.
Returns
  • PdfToPdfClient - The converter object.
func (client *PdfToPdfClient) AddPdfRawData(pdfRawData []byte) *PdfToPdfClient
Add in-memory raw PDF data to the list of the input PDFs.
Typical usage is for adding PDF created by another Pdfcrowd converter.

Example in PHP:
$clientPdf2Pdf->addPdfRawData($clientHtml2Pdf->convertUrl('http://www.example.com'));
Parameter Description Default
pdfRawData
The raw PDF data.
The input data must be PDF content.
Returns
  • PdfToPdfClient - The converter object.

 

Miscellaneous

func (client *PdfToPdfClient) SetDebugLog(debugLog bool) *PdfToPdfClient
Turn on the debug logging. Details about the conversion are stored in the debug log. The URL of the log can be obtained from the getDebugLogUrl method or available in conversion statistics.
Parameter Description Default
debugLog
Set to true to enable the debug logging.
false
Returns
  • PdfToPdfClient - The converter object.
func (client *PdfToPdfClient) GetDebugLogUrl() string
Get the URL of the debug log for the last conversion.
Returns
  • string - The link to the debug log.
func (client *PdfToPdfClient) GetRemainingCreditCount() int
Get the number of conversion credits available in your account.
The returned value can differ from the actual count if you run parallel conversions.
The special value 999999 is returned if the information is not available.
Returns
  • int - The number of credits.
func (client *PdfToPdfClient) GetConsumedCreditCount() int
Get the number of credits consumed by the last conversion.
Returns
  • int - The number of credits.
func (client *PdfToPdfClient) GetJobId() string
Get the job id.
Returns
  • string - The unique job identifier.
func (client *PdfToPdfClient) GetPageCount() int
Get the total number of pages in the output document.
Returns
  • int - The page count.
func (client *PdfToPdfClient) GetOutputSize() int
Get the size of the output in bytes.
Returns
  • int - The count of bytes.
func (client *PdfToPdfClient) SetTag(tag string) *PdfToPdfClient
Tag the conversion with a custom value. The tag is used in conversion statistics. A value longer than 32 characters is cut off.
Parameter Description Default
tag
A string with the custom tag.
Returns
  • PdfToPdfClient - The converter object.

 

API Client Options

func (client *PdfToPdfClient) SetUseHttp(useHttp bool) *PdfToPdfClient
Specifies if the client communicates over HTTP or HTTPS with Pdfcrowd API.
Parameter Description Default
useHttp
Set to true to use HTTP.
false
Returns
  • PdfToPdfClient - The converter object.
func (client *PdfToPdfClient) SetUserAgent(userAgent string) *PdfToPdfClient
Set a custom user agent HTTP header. It can be usefull if you are behind some proxy or firewall.
Parameter Description Default
userAgent
The user agent string.
pdfcrowd_go_client/4.3.5 (http://pdfcrowd.com)
Returns
  • PdfToPdfClient - The converter object.
func (client *PdfToPdfClient) SetProxy(host string, port int, userName string, password string) *PdfToPdfClient
Specifies an HTTP proxy that the API client library will use to connect to the internet.
Parameter Description Default
host
The proxy hostname.
port
The proxy port.
userName
The username.
password
The password.
Returns
  • PdfToPdfClient - The converter object.
func (client *PdfToPdfClient) SetRetryCount(retryCount int) *PdfToPdfClient
Specifies the number of retries when the 502 HTTP status code is received. The 502 status code indicates a temporary network issue. This feature can be disabled by setting to 0.
Parameter Description Default
retryCount
Number of retries wanted.
1
Returns
  • PdfToPdfClient - The converter object.

 

Error Handling

    // 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 by your way

Troubleshooting