Julia HTTP POST request with image attachment

Question

I'm struggling implementing a POST request with image attachment with the Julia HTTP package. In Python I can do (source from Pushover):

import requests
r = requests.post("https://api.pushover.net/1/messages.json", data = {
  "token": "APP_TOKEN",
  "user": "USER_KEY"
},
files = {
  "attachment": ("image.jpg", open("myimage.jpg", "rb"), "image/jpeg")
})

How can I do such a file attachment in simple ways with Julia/HTTP or another Julia package?

Many thanks!

Answer 1

This should be the equivalent request using HTTP.jl:

import HTTP
url = "http://localhost:8080" # check request with e.g. netcat -lp 8080
open("cat.jpg") do io
    headers = []
    data = [
        "token" => "APP_TOKEN",
        "user" => "USER_KEY",
        "attachment" => io,
    ]
    body = HTTP.Form(data)
    HTTP.post(url, headers, body)
end

The filename (cat.jpg) and content type (image/jpeg) is inferred from the io.

---

If you need better control, for example if you want the filename in the request to differ from the filename on disk, or if you want to manually specify Content-Type, you can manually construct a HTTP.Multipart entry, like this:

data = [
    "token" => "APP_TOKEN",
    "user" => "USER_KEY",
    "attachment" => HTTP.Multipart("other_filename.jpg", io, "image/png"),
]

---

You can compare/verify the request from HTTP.jl with the one from requests by using something like

$ netcat -lp 8080

and send the requests to http://localhost:8080.