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PouchDB Resolve Conflicts

PouchDB plugin to assist in PouchDB conflict resolving.

Disclaimer

Conflict resolution should better be done server side to avoid hard to debug loops when multiple clients resolves conflicts on the same documents.

Installation

pouch-resolve-conflicts is hosted on npm.

Node

Install via npm install pouch-resolve-conflicts

var PouchDB = require('pouchdb')
PouchDB.plugin(require('pouch-resolve-conflicts'))

Browser

Use the browserified build.

<script src="pouchdb.js"></script>
<script src="pouch-resolve-conflicts.js"></script>

Usage

// The resolve function. This function takes two documents and returns either
// one of them, a changed version of one of them, or nothing. In the latter the
// conflict will not be resolved. If there are more than two conflicting
// versions this function will be called with each version against the former
// result.
function resolveFun (a, b) {
  // cannot merge: return nothing
  if ('foo' in a && 'foo' in b) return
  
  // return one of the docs
  if ('foo' in a) return a
  if ('foo' in b) return b
  
  // return changed doc
  a.foo = 'bar'
  return a
}

var db = new PouchDB('mydb')

db
  // Lets have a conflict
  .bulkDocs({
    docs: [
      { _id: 'mydoc', _rev: '1-one', foo: 'bar' },
      { _id: 'mydoc', _rev: '1-two', bar: 'baz' }
    ],
    new_edits: false
  })
  // Query doc with `conflicts: true`
  .then(function(response) {
    return db.get('mydoc', { conflicts: true })
  })
  // And resolve it
  .then(function(doc) {
    return db.resolveConflicts(doc, resolveFun)
  })

// `resolveFun` can also return a promise:
function resolveFun (a, b) {
  return new Promise(function(resolve, reject) {
    if ('foo' in a && 'foo' in b) return resolve(undefined)

    if ('foo' in a) return resolve(a)
    if ('foo' in b) return resolve(b)

    a.foo = 'bar'
    return resolve(a)
  })
}

Tests

npm test