Fix determination of worksheet ID for new sheets

[ghing]

Tabletop.loadSheets uses this logic to determine each worksheet's ID from the worksheets feed (https://spreadsheets.google.com/feeds/worksheets/{{SPREADSHEET_KEY}}/public/basic?alt=json):

var sheet_id = data.feed.entry[i].link[3].href.substr( data.feed.entry[i].link[3].href.length - 3, 3);

For old sheets, data.feed.entry.links has 4 entries:

link: [
  {
    rel: "http://schemas.google.com/spreadsheets/2006#listfeed",
    type: "application/atom+xml",
    href: "https://spreadsheets.google.com/feeds/list/{{SPREADSHEET_KEY}}/od6/public/basic"
  },
  {
    rel: "http://schemas.google.com/spreadsheets/2006#cellsfeed",
    type: "application/atom+xml",
    href: "https://spreadsheets.google.com/feeds/cells/{{SPREADSHEET_KEY}}/od6/public/basic"
  },
  {
    rel: "http://schemas.google.com/visualization/2008#visualizationApi",
    type: "application/atom+xml",
    href: "https://spreadsheets.google.com/tq?key={{SPREADSHEET_KEY}}&sheet=od6&pub=1"
  },
  {
    rel: "self",
    type: "application/atom+xml",
    href: "https://spreadsheets.google.com/feeds/worksheets/{{SPREADSHEET_KEY}}/public/basic/od6"
  }
]

and the code correctly extracts od6 from the href property of the last link element.

For new sheets, however, data.feed.entry.links has 5 entries:

link: [
  {
    rel: "http://schemas.google.com/spreadsheets/2006#listfeed",
    type: "application/atom+xml",
    href: "https://spreadsheets.google.com/feeds/list/{{SPREADSHEET_KEY}}/od6/public/basic"
  },
  {
    rel: "http://schemas.google.com/spreadsheets/2006#cellsfeed",
    type: "application/atom+xml",
    href: "https://spreadsheets.google.com/feeds/cells/{{SPREADSHEET_KEY}}/od6/public/basic"
  },
  {
    rel: "http://schemas.google.com/visualization/2008#visualizationApi",
    type: "application/atom+xml",
    href: "https://docs.google.com/spreadsheets/d/{{SPREADSHEET_KEY}}/gviz/tq?gid=0&pub=1"
  },
  {
    rel: "http://schemas.google.com/spreadsheets/2006#exportcsv",
    type: "text/csv",
    href: "https://docs.google.com/spreadsheets/d/{{SPREADSHEET_KEY}}/export?gid=0&format=csv"
  },
  {
    rel: "self",
    type: "application/atom+xml",
    href: "https://spreadsheets.google.com/feeds/worksheets/{{SPREADSHEET_KEY}}/public/basic/od6"
  }
]

So, the code will incorrectly grab csv from the end of the fourth link element, instead of od6 from the end of the last link element.

While this method of extracting the worksheet ID seems to be too brittle in general and might be worth reconsidering, we can make the existing method work for both old and new sheets by inspecting the last link element instead of the fourth:

var linkIdx = data.feed.entry[i].link.length-1;
var sheet_id = data.feed.entry[i].link[linkIdx].href.substr( data.feed.entry[i].link[linkIdx].href.length - 3, 3);

Without this fix, we get the error "Cannot read property 'title' of undefined" in Tabletop.Model as a result of no data being retrieved from an incorrectly constructed sheet list feed URL (https://spreadsheets.google.com/feeds/list/{{SPREADSHEET_KEY}}/csv/public/values?alt=json).

Note that this pull request also contains the change for #46

[ghing]

I'll add that support for new sheets is increasingly important to me because now, when I create a new spreadsheet in Drive, it is a "new"-style sheet. I don't recall opting in and don't know if there's a way to go back.

[jsoma]

Thanks so much, digging in to all of these "new"-style sheet issues now!

[jlord]

🎉 YAY! 🎊 Thank you!