Gravity Forms
+ Availability Poll

Choosing a date for a board meeting, a parents' evening, a volunteer day or a team call usually means a long e-mail thread: one person can do Tuesday, another only in the morning, a third is in a different time zone. The Gravity Forms Availability Poll add-on turns that thread into one simple form. You list the dates and times you could meet in an Availability Poll field, share the form, and every respondent marks each time Yes, If need be or No.

A live results grid shows who answered what, counts the answers per time, colours each time by how many people can make it and highlights the best time. Show it after a person answers, place it on any page with a shortcode, and hide the names if the poll is private. Each respondent gets their own signed change link: when plans change they open it, adjust their answers and their existing entry is updated, so the count stays right. Respondents in another time zone see every time in their own local time as well, while the times are stored as exact moments.

Set a deadline and a maximum number of respondents; both are checked on the server, so a late or extra answer is refused even if the form was opened earlier. When you are ready, open the poll in your WordPress admin, close it and pick the final time. Every respondent receives the “final time chosen” notification with an .ics calendar file and add-to-calendar links. Everything runs on your own site, with no outside scheduling service and no outside connection. For Gravity Forms 2.9 and newer.

The add-on adds a new field type to Gravity Forms. You write the candidate times one date per line in the poll time zone; the add-on turns each one into an exact start and end moment in UTC with a stable id, so the same time keeps the same id even if you reorder the lines. Each answer is stored in the respondent's Gravity Forms entry as a short list of time ids and answers, which keeps entries, exports and merge tags working as usual. When the form is submitted, the add-on checks on the server that every answer belongs to one of the poll's times and is one of the allowed choices, that the deadline has not passed, that the maximum number of respondents has not been reached and that the poll is still open. A respondent's change link carries a signed key made with a secret that never leaves your site; with a valid key the submission updates that respondent's own entry through Gravity Forms, and any altered link is refused. The results grid is built from the entries each time it is shown. When you close the poll, the add-on stores the final time, writes a temporary .ics file, sends the “final time chosen” notification to every respondent through Gravity Forms with the file attached, then removes the file. The add-to-calendar links are plain links that open the respondent's own calendar with the event filled in. Everything happens on your own server — the add-on makes no outside HTTP request beyond the licence and update checks.