Conflict Management Dream API

[gr2m]

follow up for https://github.com/hoodiehq/wip-hoodie-store-on-pouchdb/issues/32 (make sure to check the discussion, lots of great thoughts in there!)

I see two ways to handle conflicts:

1. Conflicts can be automatically merged with app-specific logic
2. Show custom UI to have the user handle conflicts manually

   Dream API

I'll keep that updated based on the discussion in this issue.

// all objects returned by all hoodie.store methods and passed
// to all events (change, add, update, remove) have a _conflicts property.

// To find all objects having a conflict, use hoodie.store.findAll with a filter function
hoodie.store.findAll(function(object) {
  return object._conflicts !== undefined;
})
.then(function(objectsWithConflicts) {
  objectsWithConflicts.forEach(function(object) {
    object._conflicts // array of conflicting versions
  })
})

// To resolve a conflict, the hoodie.store update methods accept a `removeConflicts` option.
hoodie.store.update(winningObjectVersion, {removeConflicts: true})
.then(function(newObjectVersion) {
  newObjectVersion._conflicts // undefined
});

// It can also be an array of the conflicting rev IDs or entire object
hoodie.store.update(object, {removeConflicts: [losingVersion1, losingVersion2]})

// Removing an object always automatically removes all conflicting revisions
hoodie.store.remove(object)

// You can listen to conflicts happening in the background
hoodie.store.on('change', function(object) {
  if (object._conflicts) {
    // update UI and/or handle conflict
  }
})