PouchDB AngularJS adapter to monitor and manage replication status and 3-way data binding
PouchDB supports live ( or "continious") replication where changes are propogated between the two databases as the changes occur. However, in the event of going offline, something will need to restart the replication process. The PouchDB guides on replication discuss the mechanics of catching the 'error' and retrying replication, and even demonstrate the sophisticated "exponential backoff" technique.
Geoff Cox wrote a plugin pouchdb-persist to solve this exact problem.
This component (ngPouch) provides a similar approach to maintaining fault-tolerant replication, but also publishes replication details to Angular's scope. For example, it tracks (and publishes to the scope) how many un-replicated changes have occured locally, the connection status and connection attempts, as well as when data is being sent and received.
ngPouch also provides mechanisms for 3-way data binding. Its not exactly 3-way realtime binding (for good reason). We want to be smart about the commits to our database and not create un-necessary revisions. For example, we don't want to commit a revision to the database on every key stroke.
ngPouch doesn't provide any directives, but offers a handy 'publish' function to be used on controllers. The publish function is fired once on initial call and subsequently on each database change. It is smart enough not to run itself while already running so rapid fire replication doesn't cause awkward refreshing and flicker.
If the developer wants the data to "magicly refresh" then they bind it to the scope inside of ngPouch's publish procedure. If they want the data to be unbound to database changes (such as in populating and edit form) they simply bind it to the scope outside "as-normal".
ngPouch does not provide any magic for updating the pouch database from scope data or user interactions. ngPouch discourages over writing revisions as this is a common mistake. It is quite simple however, to write revisions from scope data on user events such as clicking the save button.
I think it would be good architecture to split out the problem of 3-way data binding and fault tolerant replication and provider cleaner well documented angular libraries. Also the replication updates are applied to Angular's root scope which is not ideal.
- bower install ng-pouch --save
Linux or Mac required to run pouchdb-server.
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git clone git@github.com:jrhicks/ngPouch.git
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cd ngPouch
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cd example
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npm install
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npm run db
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node app.js
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Copyright (c) 2014 Jeffrey Hicks @jrhicks
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