Direct conversion

Author: jonas-jasas

README.md

@@ -124,6 +124,16 @@ func main() {
 This is the bare-minimum to convert a file using the ConvertAPI client, but you can do a great deal more with the ConvertAPI Go library.
 Take special note that you should replace `your-api-secret` with the secret you obtained in item two of the pre-requisites.
 
+
+### Conversion Without Temporarily Storing Files on the ConvertAPI File Server
+By design, the ConvertAPI library uses a temporary file server to store files.
+A temporary file server is useful for conversion chaining and generally improves performance.
+However, the [Vanilla Go Example](examples/direct/main.go) demonstrates how to efficiently convert files without using the ConvertAPI file server.
+
+In this example, both the request and response use the `multipart` content type. This approach allows you to convert multiple files or return conversion results as multiple files.
+Using `multipart` is much more efficient compared to JSON with base64 encoding.
+
+
 ### Issues & Comments
 Please leave all comments, bugs, requests, and issues on the Issues page. We'll respond to your request ASAP!
 

examples/direct/main.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"io"
+	"mime"
+	"mime/multipart"
+	"net/http"
+	"os"
+)
+
+// Example of DOCX to PDF conversion using vanilla go.
+// File is converted without temporary storing files on ConverAPI servers.
+// No error handling to make an example easier to read.
+// No file buffering to memory. To store file to memory in general is a bad idea!
+func main() {
+	pipeReader, pipeWriter := io.Pipe()
+	multipartWriter := multipart.NewWriter(pipeWriter)
+
+	// Adjust URL according your converter and set YOUR_SECRET.
+	req, _ := http.NewRequest("POST", "https://v2.convertapi.com/convert/docx/to/pdf?secret=YOUR_SECRET", pipeReader)
+	req.Header.Set("Content-Type", multipartWriter.FormDataContentType())
+	req.Header.Set("Accept", "multipart/mixed")
+
+	go func(mpWriter *multipart.Writer) {
+		defer pipeWriter.Close()
+		defer multipartWriter.Close()
+		filePart, _ := mpWriter.CreateFormFile("file", "test.docx")
+		f, _ := os.Open("assets/test.docx") // Open file that needs to be converted
+		defer f.Close()
+		f.WriteTo(filePart)
+		// If conversion takes multiple source files, it can be added here, as an example above.
+	}(multipartWriter)
+
+	resp, _ := http.DefaultClient.Do(req)
+	save(resp, "/tmp/result.pdf")
+}
+
+func save(resp *http.Response, file string) {
+	defer resp.Body.Close()
+
+	mediaType := resp.Header.Get("Content-Type")
+	_, params, _ := mime.ParseMediaType(mediaType)
+	multipartReader := multipart.NewReader(resp.Body, params["boundary"])
+
+	part, _ := multipartReader.NextPart()
+	resFile, _ := os.Create(file)
+	defer resFile.Close()
+	io.Copy(resFile, part)
+	// If conversion returns multiple files, it can be red using multipartReader.NextPart() multiple times.
+}