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Example of doing a multipart upload in Go (golang)
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package main | |
import ( | |
"bytes" | |
"fmt" | |
"io" | |
"log" | |
"mime/multipart" | |
"net/http" | |
"os" | |
"path/filepath" | |
) | |
// Creates a new file upload http request with optional extra params | |
func newfileUploadRequest(uri string, params map[string]string, paramName, path string) (*http.Request, error) { | |
file, err := os.Open(path) | |
if err != nil { | |
return nil, err | |
} | |
defer file.Close() | |
body := &bytes.Buffer{} | |
writer := multipart.NewWriter(body) | |
part, err := writer.CreateFormFile(paramName, filepath.Base(path)) | |
if err != nil { | |
return nil, err | |
} | |
_, err = io.Copy(part, file) | |
for key, val := range params { | |
_ = writer.WriteField(key, val) | |
} | |
err = writer.Close() | |
if err != nil { | |
return nil, err | |
} | |
req, err := http.NewRequest("POST", uri, body) | |
req.Header.Set("Content-Type", writer.FormDataContentType()) | |
return req, err | |
} | |
func main() { | |
path, _ := os.Getwd() | |
path += "/test.pdf" | |
extraParams := map[string]string{ | |
"title": "My Document", | |
"author": "Matt Aimonetti", | |
"description": "A document with all the Go programming language secrets", | |
} | |
request, err := newfileUploadRequest("https://google.com/upload", extraParams, "file", "/tmp/doc.pdf") | |
if err != nil { | |
log.Fatal(err) | |
} | |
client := &http.Client{} | |
resp, err := client.Do(request) | |
if err != nil { | |
log.Fatal(err) | |
} else { | |
body := &bytes.Buffer{} | |
_, err := body.ReadFrom(resp.Body) | |
if err != nil { | |
log.Fatal(err) | |
} | |
resp.Body.Close() | |
fmt.Println(resp.StatusCode) | |
fmt.Println(resp.Header) | |
fmt.Println(body) | |
} | |
} |
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Sure. The request reads from the provided reader until it returns io.EOF. For an io.Pipe, the reader-end will return io.EOF after the write-end is closed. That's what is meant by "blocking". If the bodyWriter is not closed, the the request will last forever (until conn timeout).
https://pkg.go.dev/io#PipeWriter.Close
Closing the formWriter isn't strictly necessary to send the request. However, the formWriters Close() writes a trailer to the multipart message that is required for the request to be valid.
https://pkg.go.dev/mime/multipart#Writer.Close