OnlyDucks.gs

// Corresponding spreadsheet: https://docs.google.com/spreadsheets/d/11pse2j9nLimlgyGsxVCtcHY7vBRYchMFslR_rIReNiQ/edit?usp=sharing

function myFunction(event) {
  Logger.log(SpreadsheetApp.getActive().getUrl());
  
  Logger.log(JSON.stringify(event));
  
  row_num = event.range.rowStart;
  col_num = event.range.columnEnd;

  drive_url = event["namedValues"]["Upload your spirit duck image"][0];

  Logger.log(drive_url);
  
  //get image from drive
  // URL looks like: "https://drive.google.com/open?id=1RvOL6wT_7rXnOdjEsPl4Qi3Tm8F1K8Kk"
  var id = drive_url.split('=')[1];
  var file = DriveApp.getFileById(id);
  var file_bytes = file.getBlob().getBytes();

  labels = callVisionAPI(file_bytes);
  
  SpreadsheetApp.getActiveSheet().getRange(row_num, col_num+1).setValue(labels.join(", "));
}

function form_stub() {
  test_json = {"authMode":"FULL","namedValues":{"Upload your spirit duck image":["https://drive.google.com/open?id=1RvOL6wT_7rXnOdjEsPl4Qi3Tm8F1K8Kk"],"What is your favorite colour? ":[""],"Timestamp":["5/29/2020 15:43:02"],"What is your name?":["asdf"]},"range":{"columnEnd":4,"columnStart":1,"rowEnd":6,"rowStart":6},"source":{},"triggerUid":"3695078","values":["5/29/2020 15:43:02","asdf","","https://drive.google.com/open?id=1RvOL6wT_7rXnOdjEsPl4Qi3Tm8F1K8Kk"]}
  
  myFunction(test_json);
}

function callVisionAPI(image_bytes) {
  
  const payload = JSON.stringify({
    requests: [{
      image: {
        content: Utilities.base64Encode(image_bytes)
      },
      features: [
        {
          type:"LABEL_DETECTION",
          maxResults: 10
        },
      ]
    }]
  });

  // API_KEY should be defined in a separate file (or in this one)
  // Get your API Key by going to APIs & Services > Credentials in your GCP Console: https://console.cloud.google.com/apis/credentials
  const url = 'https://vision.googleapis.com/v1/images:annotate?key=' + API_KEY;
  
  const response = UrlFetchApp.fetch(url, {
    method: 'POST',
    contentType: 'application/json',
    payload: payload,
    muteHttpExceptions: true
  }).getContentText();
  
  const json_resp = JSON.parse(response)
  
  Logger.log(json_resp)
  
  var labels = []
  
  json_resp.responses[0].labelAnnotations.forEach(function (label) {
    labels.push(label.description)
  })
  
  return labels


}

Thank you