Facebook Messenger API Messenge Attachments example does not work

Question

I have a problem with reproducing the second example https://developers.facebook.com/docs/messenger-platform/reference/attachment-upload-api#example_request

It is:

curl  \
  -F 'message={"attachment":{"type":"image", "payload":{"is_reusable":true}}}' \
  -F 'filedata=@/tmp/shirt.png;type=image/png' \
  "https://graph.facebook.com/v6.0/me/message_attachments?access_token=<PAGE_ACCESS_TOKEN>"

When I check the request with httpbin, I get:

{
"args": {}, 
  "data": "", 
  "files": {
    "filedata": ""
  }, 
  "form": {
    "message": "{\"attachment\":{\"type\":\"image\", \"payload\":{\"is_reusable\"=true}}}", 
    "recipient": "{\"id\":\"2673203139464950\"}"
  }, 
  "headers": {
    "Accept": "*/*", 
    "Content-Length": "474", 
    "Content-Type": "multipart/form-data; boundary=------------------------855a2be7cb07aa99", 
    "Host": "httpbin.org", 
    "User-Agent": "curl/7.58.0", 
    "X-Amzn-Trace-Id": "Root=1-5e71f6ce-edeb373f3e446e443e23f2e3"
  }, 
  "json": null, 
  "origin": "my.ip.ad.dr", 
  "url": "https://httpbin.org/post"
}

When I run it locally, I get

{
   "error":{
      "message":"(#100) Field message must be a valid json object with string keys",
      "type":"OAuthException",
      "code":100,
      "fbtrace_id":"ABYTTCTcFg7DoXr8i8ySdJB"
   }
}

My attempts to solve it by myself are unsuccessful, despite several days of effort. I guess, the problem is really simple, but I need help.

By the way, in general I need python-requests way of uploading files to Facebook, thus, if I had one, I would not need curl solution.

Any help will be appreciated.

I was told to replace the equals sign with a colon and add backslashes, however, it does not seem to work:

$ curl  \
>   -F 'message:{\"attachment\":{\"type\":\"image\", \"payload\":{\"is_reusable\": true}}}' \
>   -F 'filedata=@/tmp/shirt.png;type=image/png' \
>   "https://graph.facebook.com/v6.0/me/message_attachments?access_token=<MY-TOKEN>"
Warning: Illegally formatted input field!
curl: option -F: is badly used here

Answer 1

You only want to replace the second equal sign with a colon, the one after is_reusable, otherwise the JSON you provide is not valid. The equal sign after message should stay, because it is required by curl. Check out the documentation for more details.

In your case you want to use the following:

-F 'message={"attachment":{"type":"image","payload":{"is_reusable":true}}}'