Using pre-request script

Hi all,
I have a photo upload POST request which I want to send in a “Pre-request Script” of another request. I’ve tried like this:

url: pm.environment.get("url") + '/photos/add.json?key={{user_key}}&is_public=1', 
method: 'POST',
params: [{
    "key": "user_key",
    "value": pm.variables.get("user_key"),
body: {
    mode: 'formdata',
    formdata: [{
        "src": "Users/ng/Postman/files/colorful-flower-on-dark-tropical-260nw-721703848.jp2",
}, function(err, res) {

It’s not working. I can’t find the solution

Is there any chance not having the leading slash “/” in the name of the file-path is the problem?