Changes auto-update option added

[benkeen]

This PR adds a "Auto-update changes list" option on the Changes
page, within the Filters tab. When enabled, it will automatically
update the page with whatever changes occur on the database.

[michellephung]

i think this can be: checked={this.state.pollingEnabled}

https://facebook.github.io/jest/docs/tutorial-react.html

[benkeen]

Ooh nice, thanks!

[michellephung]

+1

[garrensmith]

Instead of default value for getLastSeqNum of null rather make it return now. Changes supports the now parameter. Then you don't need to do the if statement and instead just set the since, feed and timeout.

[benkeen]

I just tried this, but for the initial request it can't be a longpoll or I don't ever get the first batch of data returned; 'now' as a default only works for future changes - for the first request I need the last N results in the past. But I refactored the code a bit to only set it to longpoll once currentRequest has been set, and removed the else. I think it's a bit better now. [Will commit in a moment]

[garrensmith]

@benkeen this is very cool. Could you add a small notification for each new change that is added. Maybe something like it changes colour slightly just so a user notices that a new set of changes have come through.

[benkeen]

@garrensmith that's a good idea, will do.

[garrensmith]

@benkeen this looks great. I'm getting a strange behaviour if I view changes. Then make a few changes to the db and then click on the filter and check auto update. It then does a lot of updating.

If I view the changes page, then check auto update and then make a few changes to the db I don't get as many updates.

[benkeen]

Ah, drat. Good catch. What's happening is that the first time you check the auto update feature it'll show all changes that have occurred since the page was originally loaded, rather than from that moment on which is what you'd expect. I'll fix it.

[benkeen]

Squashed & merged.