How do I get a buried variable from a JSON file?

July 28, 2022

This is probably a very novice question, but I am a very novice programmer, so here goes…

I am using GAS and Google Books to get the url for a book cover using this code:

function myFunction() {
  var url = "https://www.googleapis.com/books/v1/volumes?q=flowers+inauthor:keyes&country=US"
  var response = UrlFetchApp.fetch(url);
  var json = response.getContentText();
  var data = JSON.parse(json);
  Logger.log(response);
}

From my limited knowledge, I tried using this to get the proper URL:

Logger.log(data.items.imageLinks.smallThumbnail);

but it just returns an error. Is there something missing or a different way to get the variable I need?

>Solution :

The issue is that data.items is an array of 10 elements, therefore you have to index that.

If you want to access the first element:

function myFunction() {
  var url = "https://www.googleapis.com/books/v1/volumes?q=flowers+inauthor:keyes&country=US"
  var response = UrlFetchApp.fetch(url);
  var json = response.getContentText();
  var data = JSON.parse(json);
  console.log(data.items.length)
  Logger.log(data.items[0].volumeInfo.imageLinks.smallThumbnail);
}

If you want to access all elements and store it in an array:

function myFunction() {
  var url = "https://www.googleapis.com/books/v1/volumes?q=flowers+inauthor:keyes&country=US"
  var response = UrlFetchApp.fetch(url);
  var json = response.getContentText();
  var data = JSON.parse(json);
  var items = data.items;
  var smallThumbnails = items.map(x=>x.volumeInfo.imageLinks.smallThumbnail);
  Logger.log(smallThumbnails);
}

Output:

[http://books.google.com/books/content?id=gK98gXR8onwC&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api, http://books.google.com/books/content?id=LRlCAAAAYAAJ&printsec=frontcover&img=1&zoom=5&source=gbs_api, http://books.google.com/books/content?id=Fgn65IL3q4wC&printsec=frontcover&img=1&zoom=5&source=gbs_api, http://books.google.com/books/content?id=3vFDvgAACAAJ&printsec=frontcover&img=1&zoom=5&source=gbs_api, http://books.google.com/books/content?id=gK98gXR8onwC&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api, http://books.google.com/books/content?id=F1wgqlNi8AMC&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api, http://books.google.com/books/content?id=64tuPwAACAAJ&printsec=frontcover&img=1&zoom=5&source=gbs_api, http://books.google.com/books/content?id=wAUiAAAAMAAJ&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api, http://books.google.com/books/content?id=7hLQ_F0obXAC&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api, http://books.google.com/books/content?id=tVxnDwAAQBAJ&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api]