How to Convert Documents to PDF by Using Go Lang

In this tutorial we will cover how to implement asynchronous approach of Document Conversion Suite. You only need to send source document to SubmitTIFFConversionTask or SubmitPDFConversionTask API methods to receive task identifier as response. There is also SubmitDOCXConversionTask method to convert PDF documents to editable Microsoft Word document.

After receiving task identifier you need to check task status by calling GetConversionTaskStatus method. You need to call same method after a few seconds delay as long as task status equals to “Waiting”. Once you receive “Completed” from GetConversionTaskStatus method you can call DownloadResult method to download final document file. You can use the Go Lang implementation below.

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package main

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"os"
	"path/filepath"
	"time"
)

func createReqBody(filePathToConvert string, authorName string, title string, keywords string, name string) (string, io.Reader, error) {
	var err error
	buf := new(bytes.Buffer)
	bw := multipart.NewWriter(buf)

	f, err := os.Open(filePathToConvert)
	if err != nil {
		return "", nil, err
	}
	defer f.Close()

	authorNameField, _ := bw.CreateFormField("authorName")
	authorNameField.Write([]byte(authorName))

	titleField, _ := bw.CreateFormField("title")
	titleField.Write([]byte(title))

	keywordsField, _ := bw.CreateFormField("keywords")
	keywordsField.Write([]byte(keywords))

	nameField, _ := bw.CreateFormField("name")
	nameField.Write([]byte(name))

	_, fileName := filepath.Split(filePathToConvert)
	fw1, _ := bw.CreateFormFile("file", fileName)
	io.Copy(fw1, f)

	bw.Close()
	return bw.FormDataContentType(), buf, nil
}

func submitPdfConversionTask(filePath string, rapidApiKey string) (string, error) {
	contType, reader, err := createReqBody(filePath, "Sebastian", "Final report",
		"Reports, Final", "Quarterly Final Report")
	if err != nil {
		return "", err
	}

	req, err := http.NewRequest("POST", "https://petadata-document-conversion-suite.p.rapidapi.com/SubmitPDFConversionTask", reader)
	req.Header.Add("Content-Type", contType)
	req.Header.Add("X-RapidAPI-Key", rapidApiKey)

	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil || resp.StatusCode != 200 {
		fmt.Println("Cannot upload file to convert error:", err)
		return "", err
	}
	defer resp.Body.Close()
	b, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", err
	}
	return string(b), nil
}

func getConversionTaskStatus(taskId string, rapidApiKey string) (string, error) {
	url := fmt.Sprintf("https://petadata-document-conversion-suite.p.rapidapi.com/GetConversionTaskStatus?taskId=%s", taskId)
	req, err := http.NewRequest("GET", url, nil)
	req.Header.Add("X-RapidAPI-Key", rapidApiKey)

	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil || resp.StatusCode != 200 {
		fmt.Println("Cannot check conversion status of task with error:", err)
		return "", err
	}
	defer resp.Body.Close()
	b, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", err
	}
	return string(b), nil
}

func downloadResult(taskId string, rapidApiKey string) ([]byte, error) {
	url := fmt.Sprintf("https://petadata-document-conversion-suite.p.rapidapi.com/DownloadResult?taskId=%s", taskId)
	req, err := http.NewRequest("GET", url, nil)
	req.Header.Add("X-RapidAPI-Key", rapidApiKey)

	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil || resp.StatusCode != 200 {
		fmt.Println("Cannot download converted file with error:", err)
		return nil, err
	}
	defer resp.Body.Close()
	b, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	return b, nil
}

func main() {
	filePathToConvert := "<FILE PATH TO CONVERT>"
	rapidApiKey := "<YOUR RAPIDAPI KEY HERE>"
	taskId, err := submitPdfConversionTask(filePathToConvert, rapidApiKey)
	if err != nil {
		panic(err)
	}
	retryCount := 0
	for retryCount < 100 {
		retryCount++
		time.Sleep(5 * time.Second)
		status, err := getConversionTaskStatus(taskId, rapidApiKey)
		if err != nil {
			panic(err)
		}
		if status == "Completed" {
			fileBytes, err := downloadResult(taskId, rapidApiKey)
			if err != nil {
				panic(err)
			}
			err = os.WriteFile("final_report.pdf", fileBytes, 0644)
			if err != nil {
				panic(err)
			}
			break
		} else if status == "Waiting" {
			continue
		} else if status == "Failed" {
			panic(errors.New("Cannot convert file"))
		} else {
			panic(errors.New("Cannot convert file"))
		}
	}
}