Add replication example
This commit is contained in:
Ritchie Martori
parent
1a13a8d95e
commit
2582c3fc65
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@ -0,0 +1,138 @@
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var loopback = require('../../');
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var app = loopback();
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var db = app.dataSource('db', {connector: loopback.Memory});
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var Color = app.model('color', {dataSource: 'db', options: {trackChanges: true}});
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var Color2 = app.model('color2', {dataSource: 'db', options: {trackChanges: true}});
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var target = Color2;
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var source = Color;
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var SPEED = process.env.SPEED || 100;
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var conflicts;
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var steps = [
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createSomeInitialSourceData,
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replicateSourceToTarget,
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list.bind(this, source, 'current SOURCE data'),
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list.bind(this, target, 'current TARGET data'),
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updateSomeTargetData,
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replicateSourceToTarget,
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list.bind(this, source, 'current SOURCE data '),
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list.bind(this, target, 'current TARGET data (includes conflicting update)'),
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updateSomeSourceDataCausingAConflict,
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replicateSourceToTarget,
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list.bind(this, source, 'current SOURCE data (now has a conflict)'),
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list.bind(this, target, 'current TARGET data (includes conflicting update)'),
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resolveAllConflicts,
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replicateSourceToTarget,
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list.bind(this, source, 'current SOURCE data (conflict resolved)'),
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list.bind(this, target, 'current TARGET data (conflict resolved)'),
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createMoreSourceData,
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replicateSourceToTarget,
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list.bind(this, source, 'current SOURCE data'),
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list.bind(this, target, 'current TARGET data'),
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createEvenMoreSourceData,
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replicateSourceToTarget,
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list.bind(this, source, 'current SOURCE data'),
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list.bind(this, target, 'current TARGET data'),
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deleteAllSourceData,
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replicateSourceToTarget,
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list.bind(this, source, 'current SOURCE data (empty)'),
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list.bind(this, target, 'current TARGET data (empty)'),
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createSomeNewSourceData,
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replicateSourceToTarget,
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list.bind(this, source, 'current SOURCE data'),
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list.bind(this, target, 'current TARGET data')
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];
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run(steps);
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function createSomeInitialSourceData() {
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Color.create([
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{name: 'red'},
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{name: 'blue'},
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{name: 'green'}
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]);
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}
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function replicateSourceToTarget() {
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Color.replicate(0, Color2, {}, function(err, replicationConflicts) {
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conflicts = replicationConflicts;
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});
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}
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function resolveAllConflicts() {
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if(conflicts.length) {
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conflicts.forEach(function(conflict) {
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conflict.resolve();
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});
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}
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}
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function updateSomeTargetData() {
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Color2.findById(1, function(err, color) {
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color.name = 'conflict';
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color.save();
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});
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}
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function createMoreSourceData() {
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Color.create({name: 'orange'});
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}
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function createEvenMoreSourceData() {
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Color.create({name: 'black'});
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}
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function updateSomeSourceDataCausingAConflict() {
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Color.findById(1, function(err, color) {
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color.name = 'red!!!!';
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color.save();
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});
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}
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function deleteAllSourceData() {
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Color.destroyAll();
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}
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function createSomeNewSourceData() {
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Color.create([
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{name: 'violet'},
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{name: 'amber'},
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{name: 'olive'}
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]);
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}
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function list(model, msg) {
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console.log(msg);
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model.find(function(err, items) {
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items.forEach(function(item) {
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console.log(' -', item.name);
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});
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console.log();
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});
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}
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function run(steps) {
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setInterval(function() {
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var step = steps.shift();
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if(step) {
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console.log(step.name);
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step();
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}
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}, SPEED);
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}
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@ -27,7 +27,7 @@ var properties = {
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*/
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var options = {
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trackChanges: false
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};
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/**
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@ -55,6 +55,12 @@ Change.CREATE = 'create';
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Change.DELETE = 'delete';
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Change.UNKNOWN = 'unknown';
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/*!
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* Conflict Class
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*/
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Change.Conflict = Conflict;
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/*!
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* Setup the extended model.
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*/
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@ -149,13 +155,34 @@ Change.findOrCreate = function(modelName, modelId, callback) {
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Change.prototype.rectify = function(cb) {
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var change = this;
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this.prev = this.rev;
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// get the current revision
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this.currentRevision(function(err, rev) {
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if(err) return Change.handleError(err, cb);
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change.rev = rev;
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var tasks = [
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updateRevision,
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updateCheckpoint
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];
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if(this.rev) this.prev = this.rev;
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async.parallel(tasks, function(err) {
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if(err) return cb(err);
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change.save(cb);
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});
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function updateRevision(cb) {
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// get the current revision
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change.currentRevision(function(err, rev) {
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if(err) return Change.handleError(err, cb);
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change.rev = rev;
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cb();
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});
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}
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function updateCheckpoint(cb) {
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change.constructor.getCheckpointModel().current(function(err, checkpoint) {
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if(err) return Change.handleError(err);
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change.checkpoint = ++checkpoint;
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cb();
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});
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}
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}
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/**
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@ -233,7 +260,7 @@ Change.prototype.type = function() {
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Change.prototype.getModelCtor = function() {
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// todo - not sure if this works with multiple data sources
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return this.constructor.modelBuilder.models[this.modelName];
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return loopback.getModel(this.modelName);
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}
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/**
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@ -306,7 +333,10 @@ Change.diff = function(modelName, since, remoteChanges, callback) {
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if(err) return callback(err);
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var deltas = [];
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var conflicts = [];
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var localModelIds = [];
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localChanges.forEach(function(localChange) {
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localModelIds.push(localChange.modelId);
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var remoteChange = remoteChangeIndex[localChange.modelId];
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if(!localChange.equals(remoteChange)) {
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if(remoteChange.isBasedOn(localChange)) {
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@ -317,9 +347,91 @@ Change.diff = function(modelName, since, remoteChanges, callback) {
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}
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});
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modelIds.forEach(function(id) {
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if(localModelIds.indexOf(id) === -1) {
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deltas.push(remoteChangeIndex[id]);
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}
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});
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callback(null, {
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deltas: deltas,
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conflicts: conflicts
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});
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});
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}
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/**
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* Correct all change list entries.
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* @param {Function} callback
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*/
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Change.rectifyAll = function(cb) {
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// this should be optimized
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this.find(function(err, changes) {
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if(err) return cb(err);
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changes.forEach(function(change) {
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change.rectify();
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});
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});
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}
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/**
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* Get the checkpoint model.
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* @return {Checkpoint}
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*/
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Change.getCheckpointModel = function() {
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var checkpointModel = this.Checkpoint;
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if(checkpointModel) return checkpointModel;
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this.checkpoint = checkpointModel = require('./checkpoint').extend('checkpoint');
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checkpointModel.attachTo(this.dataSource);
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return checkpointModel;
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}
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/**
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* When two changes conflict a conflict is created.
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*
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* **Note: call `conflict.fetch()` to get the `target` and `source` models.
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*
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* @param {Change} sourceChange The change object for the source model
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* @param {Change} targetChange The conflicting model's change object
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* @property {Model} source The source model instance
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* @property {Model} target The target model instance
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*/
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function Conflict(sourceChange, targetChange) {
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this.sourceChange = sourceChange;
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this.targetChange = targetChange;
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}
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Conflict.prototype.fetch = function(cb) {
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var conflict = this;
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var tasks = [
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getSourceModel,
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getTargetModel
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];
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async.parallel(tasks, cb);
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function getSourceModel(change, cb) {
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conflict.sourceModel.getModel(function(err, model) {
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if(err) return cb(err);
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conflict.source = model;
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cb();
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});
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}
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function getTargetModel(cb) {
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conflict.targetModel.getModel(function(err, model) {
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if(err) return cb(err);
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conflict.target = model;
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cb();
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});
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}
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}
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Conflict.prototype.resolve = function(cb) {
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this.sourceChange.prev = this.targetChange.rev;
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this.sourceChange.save(cb);
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}
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@ -48,8 +48,9 @@ Checkpoint.current = function(cb) {
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this.find({
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limit: 1,
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sort: 'id DESC'
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}, function(err, checkpoint) {
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}, function(err, checkpoints) {
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if(err) return cb(err);
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var checkpoint = checkpoints[0] || {id: 0};
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cb(null, checkpoint.id);
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});
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}
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@ -4,13 +4,76 @@
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var loopback = require('../loopback');
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var ModelBuilder = require('loopback-datasource-juggler').ModelBuilder;
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var modeler = new ModelBuilder();
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var async = require('async');
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var assert = require('assert');
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/**
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* The built in loopback.Model.
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* The base class for **all models**.
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*
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* **Inheriting from `Model`**
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*
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* ```js
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* var properties = {...};
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* var options = {...};
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* var MyModel = loopback.Model.extend('MyModel', properties, options);
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* ```
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*
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* **Options**
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*
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* - `trackChanges` - If true, changes to the model will be tracked. **Required
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* for replication.**
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*
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* **Events**
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*
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* #### Event: `changed`
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*
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* Emitted after a model has been successfully created, saved, or updated.
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*
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* ```js
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* MyModel.on('changed', function(inst) {
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* console.log('model with id %s has been changed', inst.id);
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* // => model with id 1 has been changed
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* });
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* ```
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*
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* #### Event: `deleted`
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*
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* Emitted after an individual model has been deleted.
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*
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* ```js
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* MyModel.on('deleted', function(inst) {
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* console.log('model with id %s has been deleted', inst.id);
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* // => model with id 1 has been deleted
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* });
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* ```
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*
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* #### Event: `deletedAll`
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*
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* Emitted after an individual model has been deleted.
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*
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* ```js
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* MyModel.on('deletedAll', function(where) {
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* if(where) {
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* console.log('all models where', where, 'have been deleted');
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* // => all models where
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* // => {price: {gt: 100}}
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* // => have been deleted
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* }
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* });
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* ```
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*
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* #### Event: `attached`
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*
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* Emitted after a `Model` has been attached to an `app`.
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*
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* #### Event: `dataSourceAttached`
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*
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* Emitted after a `Model` has been attached to a `DataSource`.
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*
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* @class
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* @param {Object} data
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* @property {String} modelName The name of the model
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* @property {DataSource} dataSource
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*/
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var Model = module.exports = modeler.define('Model');
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@ -23,6 +86,7 @@ Model.shared = true;
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Model.setup = function () {
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var ModelCtor = this;
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var options = this.settings;
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ModelCtor.sharedCtor = function (data, id, fn) {
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if(typeof data === 'function') {
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@ -108,6 +172,13 @@ Model.setup = function () {
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ModelCtor.sharedCtor.returns = {root: true};
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ModelCtor.once('dataSourceAttached', function() {
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// enable change tracking (usually for replication)
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if(options.trackChanges) {
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ModelCtor.enableChangeTracking();
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}
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});
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return ModelCtor;
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};
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@ -219,7 +290,7 @@ Model.diff = function(since, remoteChanges, callback) {
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*/
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Model.changes = function(since, filter, callback) {
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var idName = this.idName();
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var idName = this.dataSource.idName(this.modelName);
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var Change = this.getChangeModel();
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var model = this;
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@ -235,15 +306,16 @@ Model.changes = function(since, filter, callback) {
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}, function(err, changes) {
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if(err) return cb(err);
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var ids = changes.map(function(change) {
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return change.modelId;
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return change.modelId.toString();
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});
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filter.where[idName] = {inq: ids};
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model.find(filter, function(err, models) {
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if(err) return cb(err);
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var modelIds = models.map(function(m) {
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return m[idName];
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return m[idName].toString();
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});
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callback(null, changes.filter(function(ch) {
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if(ch.type() === Change.DELETE) return true;
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return modelIds.indexOf(ch.modelId) > -1;
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}));
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});
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@ -257,7 +329,7 @@ Model.changes = function(since, filter, callback) {
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*/
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Model.checkpoint = function(cb) {
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var Checkpoint = this.getChangeModel().Checkpoint;
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var Checkpoint = this.getChangeModel().getCheckpointModel();
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this.getSourceId(function(err, sourceId) {
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if(err) return cb(err);
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Checkpoint.create({
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@ -283,18 +355,29 @@ Model.replicate = function(since, targetModel, options, callback) {
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var sourceModel = this;
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var diff;
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var updates;
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var Change = this.getChangeModel();
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var TargetChange = targetModel.getChangeModel();
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var tasks = [
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getLocalChanges,
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getDiffFromTarget,
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createSourceUpdates,
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bulkUpdate,
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sourceModel.checkpoint.bind(sourceModel)
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checkpoint
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];
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async.waterfall(tasks, function(err) {
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if(err) return callback(err);
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callback(null, diff.conflicts);
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var conflicts = diff.conflicts.map(function(change) {
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var sourceChange = new Change({
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modelName: sourceModel.modelName,
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modelId: change.modelId
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});
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var targetChange = new TargetChange(change);
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return new Change.Conflict(sourceChange, targetChange);
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});
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callback(null, conflicts);
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});
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function getLocalChanges(cb) {
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@ -307,12 +390,18 @@ Model.replicate = function(since, targetModel, options, callback) {
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function createSourceUpdates(_diff, cb) {
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diff = _diff;
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diff.conflicts = diff.conflicts || [];
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sourceModel.createUpdates(diff.deltas, cb);
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}
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function bulkUpdate(updates, cb) {
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targetModel.bulkUpdate(updates, cb);
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}
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function checkpoint() {
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var cb = arguments[arguments.length - 1];
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sourceModel.checkpoint(cb);
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}
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}
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/**
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@ -328,10 +417,10 @@ Model.createUpdates = function(deltas, cb) {
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var updates = [];
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var Model = this;
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var tasks = [];
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var type = change.type();
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deltas.forEach(function(change) {
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change = new Change(change);
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var change = new Change(change);
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var type = change.type();
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var update = {type: type, change: change};
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switch(type) {
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case Change.CREATE:
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@ -339,7 +428,11 @@ Model.createUpdates = function(deltas, cb) {
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tasks.push(function(cb) {
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Model.findById(change.modelId, function(err, inst) {
|
||||
if(err) return cb(err);
|
||||
if(inst.toObject) {
|
||||
update.data = inst.toObject();
|
||||
} else {
|
||||
update.data = inst;
|
||||
}
|
||||
updates.push(update);
|
||||
cb();
|
||||
});
|
||||
|
|
@ -369,16 +462,22 @@ Model.createUpdates = function(deltas, cb) {
|
|||
Model.bulkUpdate = function(updates, callback) {
|
||||
var tasks = [];
|
||||
var Model = this;
|
||||
var idName = Model.idName();
|
||||
var idName = this.dataSource.idName(this.modelName);
|
||||
var Change = this.getChangeModel();
|
||||
|
||||
updates.forEach(function(update) {
|
||||
switch(update.type) {
|
||||
case Change.UPDATE:
|
||||
case Change.CREATE:
|
||||
tasks.push(Model.upsert.bind(Model, update.data));
|
||||
// var model = new Model(update.data);
|
||||
// tasks.push(model.save.bind(model));
|
||||
tasks.push(function(cb) {
|
||||
var model = new Model(update.data);
|
||||
debugger;
|
||||
model.save(cb);
|
||||
});
|
||||
break;
|
||||
case: Change.DELETE:
|
||||
case Change.DELETE:
|
||||
var data = {};
|
||||
data[idName] = update.change.modelId;
|
||||
var model = new Model(data);
|
||||
|
|
@ -391,5 +490,58 @@ Model.bulkUpdate = function(updates, callback) {
|
|||
}
|
||||
|
||||
Model.getChangeModel = function() {
|
||||
|
||||
var changeModel = this.Change;
|
||||
if(changeModel) return changeModel;
|
||||
this.Change = changeModel = require('./change').extend(this.modelName + '-change');
|
||||
changeModel.attachTo(this.dataSource);
|
||||
return changeModel;
|
||||
}
|
||||
|
||||
Model.getSourceId = function(cb) {
|
||||
cb(null, 'foo')
|
||||
}
|
||||
|
||||
/**
|
||||
* Enable the tracking of changes made to the model. Usually for replication.
|
||||
*/
|
||||
|
||||
Model.enableChangeTracking = function() {
|
||||
var Model = this;
|
||||
var Change = Model.getChangeModel();
|
||||
var cleanupInterval = Model.settings.changeCleanupInterval || 30000;
|
||||
|
||||
Model.on('changed', function(obj) {
|
||||
Change.track(Model.modelName, [obj.id], function(err) {
|
||||
if(err) {
|
||||
console.error(Model.modelName + ' Change Tracking Error:');
|
||||
console.error(err);
|
||||
}
|
||||
});
|
||||
});
|
||||
|
||||
Model.on('deleted', function(obj) {
|
||||
Change.track(Model.modelName, [obj.id], function(err) {
|
||||
if(err) {
|
||||
console.error(Model.modelName + ' Change Tracking Error:');
|
||||
console.error(err);
|
||||
}
|
||||
});
|
||||
});
|
||||
|
||||
Model.on('deletedAll', cleanup);
|
||||
|
||||
// initial cleanup
|
||||
cleanup();
|
||||
|
||||
// cleanup
|
||||
setInterval(cleanup, cleanupInterval);
|
||||
|
||||
function cleanup() {
|
||||
Change.rectifyAll(function(err) {
|
||||
if(err) {
|
||||
console.error(Model.modelName + ' Change Cleanup Error:');
|
||||
console.error(err);
|
||||
}
|
||||
});
|
||||
}
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue