Handle StaleElement exception - ruby

Question

I have a table in which data can be refreshed by selecting some filter checkboxes. One or more checkboxes can be selected and after each is selected a spinner is displayed on the page. Subsequent filters can only be selected once the previous selection has refreshed the table. The issue I am facing is that I keep getting StaleElementException intermittently.
This is what I do in capybara -
visit('/table-page') # table with default values is displayed
# select all filters one by one. Wait for spinner to disappear after each selection
filters.each {|filter| check(filter); has_no_css?('.loading-overlay', wait: 15)}
# get table data as array of arrays. Added *minimum* so it waits for table
all('tbody tr', minimum: 1).map { |row| row.all('th,td').map(&:text) }
I am struggling to understand why am I seeing StaleElementException. AFAIK Capybara uses synchronize to reload node when using text method on a given node. It also happens that sometimes the table data returns stale data(i.e the one before the last filter update)

Answer 1

The use of all or first disables reloading of any elements returned (If you use find the element is reloadable since the query used to locate the element is fully known). This means that if the page changes at all during the time the last line of your code is running you'll end up with the StaleElement errors. This is possible in your code because has_no_css? can run before the overlay appears. One solution to this is to use has_css? with a short wait time, to detect the overlay before checking that it disappears. The has_xxx? methods just return true/false and don't raise errors so worst case has_css? misses the appearance/disappearance of the overlay completely and basically devolves into a sleep for the specified wait time.
visit('/table-page') # table with default values is displayed
# select all filters one by one. Wait for spinner to disappear after each selection
filters.each do |filter|
check(filter);
has_css?('.loading_overlay', wait: 1)
assert_no_selector('.loading-overlay', wait: 15)
end
# get table data as array of arrays. Added *minimum* so it waits for table
all('tbody tr', minimum: 1).map { |row| row.all('th,td').map(&:text) }