Need hoodie.database.on('change', change) and db.on('change', change) methods

[inator]

My dream additions allow for _db_updates (couchDB-wide) and _changes (for individual dbs) to be exposed through the plugin api.

Could pass an object with type (updated, created, deleted) and other pertenent details much like: npm follow-db-updates:

https://npmjs.org/package/follow-db-updates

[nintra]

i suggest the following additions to the api. as far as i know we can't track 'created' events for documents without huge additional effort because it might be that a document got created, and updated client-side before sync happened. we can say that the document got deleted because of a _deleted flag.

if there are no objections ( @inator @janl ) i would start implementing it.
it would affect:

• plugins-manager
• plugins-api
• plugin-users (minor changes)

i have a little trouble executing the tests on my windows laptop. i could use some help for the final testing. (i need a linux setup soon :) )

/**
 * event emitter that automatically listens on all user databases
 * type   document-type
 * action 'update', 'remove', '*'
 */
hoodie.userDatabases.on('type:action', function(dbName, userId, doc) { /* ... */ });


/**
 * get user database, sugar for hoodie.database('user/'+userId)
 */
hoodie.userDatabases.get(userId);


/**
 * scoped events
 */
hoodie.userDatabases.get(userId).on('type:action', function(doc) { /* ... */ });


/**
 * listen for events on specific non-user databases
 * returns an db event emitter
 * if it is a user database, return special userDb event emitter
 */
var reportEvents = hoodie.database('reports').events();
reportEvents.on('report:update', function(doc) { /* ... */ });
reportEvents.on('report:remove', function(doc) { /* ... */ });

[nintra]

i would also add a replicate method. this way you can work with data across all user accounts. (read-only) write operations have to be executed in a specific user database.

/**
 * start replicating user documents of `type` into a single database `dbName`
 * - if no dbName is provided: dbName = type + 's';
 * - create database
 * - listen for changes and copy/remove docs in one direction only
 */
hoodie.userDatabases.replicate(type, [dbName], function(error, dbName) { /* ... */ });

[gr2m]

instead of

var reportEvents = hoodie.database('reports').events();
reportEvents.on('report:update', function(doc) { /* ... */ });
reportEvents.on('report:remove', function(doc) { /* ... */ });

I'd do

var reportsDb = hoodie.database('reports')
reportsDb.on('report:update', function(doc) { /* ... */ });
reportsDb.on('report:remove', function(doc) { /* ... */ });

[nintra]

@gr2m
yes, you are right. we could do that and just wait for the first .on() to setup listening to that database. I just want to avoid to always listen to all databases. im afraid it might be some kind of overkill?

[gr2m]

yeah you can do something like this:
https://github.com/hoodiehq/pouchdb-hoodie-api/blob/events/on.js#L23-L50

start listening on the first .on call

[janl]

@nintra let’s make the replicate() a separate discussion/PR.

The rest looks good, happy to help testing on *nix.