Support multi-tenancy in change replication - allow apps to extend Change model with extra properties

common/models/change.js

@@ -184,16 +184,32 @@ module.exports = function(Change) {
 
     cb = cb || utils.createPromiseCallback();
 
-    change.currentRevision(function(err, rev) {
+    const model = this.getModelCtor();
+    const id = this.getModelId();
+
+    model.findById(id, function(err, inst) {
       if (err) return cb(err);
 
+      if (inst) {
+        inst.fillCustomChangeProperties(change, function() {
+          const rev = Change.revisionForInst(inst);
+          prepareAndDoRectify(rev);
+        });
+      } else {
+        prepareAndDoRectify(null);
+      }
+    });
+
+    return cb.promise;
+
+    function prepareAndDoRectify(rev) {
       // avoid setting rev and prev to the same value
       if (currentRev === rev) {
         change.debug('rev and prev are equal (not updating anything)');
         return cb(null, change);
       }
 
-      // FIXME(@bajtos) Allo callers to pass in the checkpoint value
+      // FIXME(@bajtos) Allow callers to pass in the checkpoint value
       // (or even better - a memoized async function to get the cp value)
       // That will enable `rectifyAll` to cache the checkpoint value
       change.constructor.getCheckpointModel().current(
@@ -202,8 +218,7 @@ module.exports = function(Change) {
           doRectify(checkpoint, rev);
         }
       );
-    });
-    return cb.promise;
+    }
 
     function doRectify(checkpoint, rev) {
       if (rev) {
@@ -228,7 +243,7 @@ module.exports = function(Change) {
           if (currentRev) {
             change.prev = currentRev;
           } else if (!change.prev) {
-            change.debug('ERROR - could not determing prev');
+            change.debug('ERROR - could not determine prev');
             change.prev = Change.UNKNOWN;
           }
           change.debug('updated prev');

lib/persisted-model.js

@@ -1052,17 +1052,15 @@ module.exports = function(registry) {
     var idName = this.dataSource.idName(this.modelName);
     var Change = this.getChangeModel();
     var model = this;
+    const changeFilter = this.createChangeFilter(since, filter);
 
     filter = filter || {};
     filter.fields = {};
     filter.where = filter.where || {};
     filter.fields[idName] = true;
 
     // TODO(ritch) this whole thing could be optimized a bit more
-    Change.find({where: {
-      checkpoint: {gte: since},
-      modelName: this.modelName,
-    }}, function(err, changes) {
+    Change.find(changeFilter, function(err, changes) {
       if (err) return callback(err);
       if (!Array.isArray(changes) || changes.length === 0) return callback(null, []);
       var ids = changes.map(function(change) {
@@ -1759,11 +1757,12 @@ module.exports = function(registry) {
     assert(BaseChangeModel,
       'Change model must be defined before enabling change replication');
 
+    const additionalChangeModelProperties =
+      this.settings.additionalChangeModelProperties || {};
+
     this.Change = BaseChangeModel.extend(this.modelName + '-change',
-      {},
-      {
-        trackModel: this,
-      }
+      additionalChangeModelProperties,
+      {trackModel: this}
     );
 
     if (this.dataSource) {
@@ -1928,6 +1927,77 @@ module.exports = function(registry) {
     }
   };
 
+  /**
+   * Get the filter for searching related changes.
+   *
+   * Models should override this function to copy properties
+   * from the model instance filter into the change search filter.
+   *
+   * ```js
+   * module.exports = (TargetModel, config) => {
+   *   TargetModel.createChangeFilter = function(since, modelFilter) {
+   *     const filter = this.base.createChangeFilter.apply(this, arguments);
+   *     if (modelFilter && modelFilter.where && modelFilter.where.tenantId) {
+   *       filter.where.tenantId = modelFilter.where.tenantId;
+   *     }
+   *     return filter;
+   *   };
+   * };
+   * ```
+   *
+   * @param {Number} since Return only changes since this checkpoint.
+   * @param {Object} modelFilter Filter describing which model instances to
+   * include in the list of changes.
+   * @returns {Object} The filter object to pass to `Change.find()`. Default:
+   * ```
+   * {where: {checkpoint: {gte: since}, modelName: this.modelName}}
+   * ```
+   */
+  PersistedModel.createChangeFilter = function(since, modelFilter) {
+    return {
+      where: {
+        checkpoint: {gte: since},
+        modelName: this.modelName,
+      },
+    };
+  };
+
+  /**
+   * Add custom data to the Change instance.
+   *
+   * Models should override this function to duplicate model instance properties
+   * to the Change instance properties, typically to allow the changes() method
+   * to filter the changes using these duplicated properties directly while
+   * querying the Change model.
+   *
+   * ```js
+   * module.exports = (TargetModel, config) => {
+   *   TargetModel.prototype.fillCustomChangeProperties = function(change, cb) {
+   *     var inst = this;
+   *     const base = this.constructor.base;
+   *     base.prototype.fillCustomChangeProperties.call(this, change, err => {
+   *       if (err) return cb(err);
+   *
+   *       if (inst && inst.tenantId) {
+   *         change.tenantId = inst.tenantId;
+   *       } else {
+   *         change.tenantId = null;
+   *       }
+   *
+   *       cb();
+   *     });
+   *   };
+   * };
+   * ```
+   *
+   * @callback {Function} callback
+   * @param {Error} err Error object; see [Error object](http://loopback.io/doc/en/lb3/Error-object.html).
+   */
+  PersistedModel.prototype.fillCustomChangeProperties = function(change, cb) {
+    // no-op by default
+    cb();
+  };
+
   PersistedModel.setup();
 
   return PersistedModel;

test/change.test.js

@@ -9,9 +9,9 @@ var async = require('async');
 var expect = require('./helpers/expect');
 var loopback = require('../');
 
-var Change, TestModel;
-
 describe('Change', function() {
+  let Change, TestModel;
+
   beforeEach(function() {
     var memory = loopback.createDataSource({
       connector: loopback.Memory,
@@ -321,7 +321,6 @@ describe('Change', function() {
       change.rectify()
         .then(function(ch) {
           assert.equal(ch.rev, test.revisionForModel);
-
           done();
         })
         .catch(done);
@@ -609,3 +608,68 @@ describe('Change', function() {
     });
   });
 });
+
+describe('Change with with custom properties', function() {
+  let Change, TestModel;
+
+  beforeEach(function() {
+    let memory = loopback.createDataSource({
+      connector: loopback.Memory,
+    });
+
+    TestModel = loopback.PersistedModel.extend('ChangeTestModelWithTenant',
+      {
+        id: {id: true, type: 'string', defaultFn: 'guid'},
+        tenantId: 'string',
+      },
+      {
+        trackChanges: true,
+        additionalChangeModelProperties: {tenantId: 'string'},
+      });
+    this.modelName = TestModel.modelName;
+
+    TestModel.prototype.fillCustomChangeProperties = function(change, cb) {
+      var inst = this;
+
+      if (inst && inst.tenantId) {
+        change.tenantId = inst.tenantId;
+      } else {
+        change.tenantId = null;
+      }
+
+      cb();
+    };
+
+    TestModel.attachTo(memory);
+    TestModel._defineChangeModel();
+    Change = TestModel.getChangeModel();
+  });
+
+  describe('change.rectify', function() {
+    const TENANT_ID = '123';
+    let change;
+
+    beforeEach(givenChangeInstance);
+
+    it('stores the custom property in the Change instance', function() {
+      return change.rectify().then(function(ch) {
+        expect(ch.toObject()).to.have.property('tenantId', TENANT_ID);
+      });
+    });
+
+    function givenChangeInstance() {
+      const data = {
+        foo: 'bar',
+        tenantId: TENANT_ID,
+      };
+
+      return TestModel.create(data)
+        .then(function(model) {
+          const modelName = TestModel.modelName;
+          return Change.findOrCreateChange(modelName, model.id);
+        }).then(function(ch) {
+          change = ch;
+        });
+    }
+  });
+});

test/replication.test.js

@@ -1905,3 +1905,131 @@ describe('Replication / Change APIs', function() {
     });
   }
 });
+
+describe('Replication / Change APIs with custom change properties', function() {
+  this.timeout(10000);
+  var dataSource, useSinceFilter, SourceModel, TargetModel, startingCheckpoint;
+  var tid = 0; // per-test unique id used e.g. to build unique model names
+
+  beforeEach(function() {
+    tid++;
+    useSinceFilter = false;
+    var test = this;
+
+    dataSource = this.dataSource = loopback.createDataSource({
+      connector: loopback.Memory,
+    });
+    SourceModel = this.SourceModel = PersistedModel.extend(
+      'SourceModelWithCustomChangeProperties-' + tid,
+      {
+        id: {id: true, type: String, defaultFn: 'guid'},
+        customProperty: {type: 'string'},
+      },
+      {
+        trackChanges: true,
+        additionalChangeModelProperties: {customProperty: {type: 'string'}},
+      });
+
+    SourceModel.createChangeFilter = function(since, modelFilter) {
+      const filter = this.base.createChangeFilter.apply(this, arguments);
+      if (modelFilter && modelFilter.where && modelFilter.where.customProperty)
+        filter.where.customProperty = modelFilter.where.customProperty;
+      return filter;
+    };
+
+    SourceModel.prototype.fillCustomChangeProperties = function(change, cb) {
+      const customProperty = this.customProperty;
+      const base = this.constructor.base;
+      base.prototype.fillCustomChangeProperties.call(this, change, err => {
+        if (err) return cb(err);
+        change.customProperty = customProperty;
+        cb();
+      });
+    };
+
+    SourceModel.attachTo(dataSource);
+
+    TargetModel = this.TargetModel = PersistedModel.extend(
+      'TargetModelWithCustomChangeProperties-' + tid,
+      {
+        id: {id: true, type: String, defaultFn: 'guid'},
+        customProperty: {type: 'string'},
+      },
+      {
+        trackChanges: true,
+        additionalChangeModelProperties: {customProperty: {type: 'string'}},
+      });
+
+    var ChangeModelForTarget = TargetModel.Change;
+    ChangeModelForTarget.Checkpoint = loopback.Checkpoint.extend('TargetCheckpoint');
+    ChangeModelForTarget.Checkpoint.attachTo(dataSource);
+
+    TargetModel.attachTo(dataSource);
+
+    startingCheckpoint = -1;
+  });
+
+  describe('Model._defineChangeModel()', function() {
+    it('defines change model with custom properties', function() {
+      var changeModel = SourceModel.getChangeModel();
+      var changeModelProperties = changeModel.definition.properties;
+
+      expect(changeModelProperties).to.have.property('customProperty');
+    });
+  });
+
+  describe('Model.changes(since, filter, callback)', function() {
+    beforeEach(givenSomeSourceModelInstances);
+
+    it('queries changes using customized filter', function(done) {
+      var filterUsed = mockChangeFind(this.SourceModel);
+
+      SourceModel.changes(
+        startingCheckpoint,
+        {where: {customProperty: '123'}},
+        function(err, changes) {
+          if (err) return done(err);
+          expect(filterUsed[0]).to.eql({
+            where: {
+              checkpoint: {gte: -1},
+              modelName: SourceModel.modelName,
+              customProperty: '123',
+            },
+          });
+          done();
+        });
+    });
+
+    it('query returns the matching changes', function(done) {
+      SourceModel.changes(
+        startingCheckpoint,
+        {where: {customProperty: '123'}},
+        function(err, changes) {
+          expect(changes).to.have.length(1);
+          expect(changes[0]).to.have.property('customProperty', '123');
+          done();
+        });
+    });
+
+    function givenSomeSourceModelInstances(done) {
+      const data = [
+        {name: 'foo', customProperty: '123'},
+        {name: 'foo', customPropertyValue: '456'},
+      ];
+      this.SourceModel.create(data, done);
+    }
+  });
+
+  function mockChangeFind(Model) {
+    var filterUsed = [];
+
+    Model.getChangeModel().find = function(filter, cb) {
+      filterUsed.push(filter);
+      if (cb) {
+        process.nextTick(cb);
+      }
+    };
+
+    return filterUsed;
+  }
+});