Implemented polymorphic hasMany

lib/relation-definition.js

@@ -64,8 +64,11 @@ function RelationDefinition(definition) {
   assert(this.modelFrom, 'Source model is required');
   this.keyFrom = definition.keyFrom;
   this.modelTo = definition.modelTo;
-  assert(this.modelTo, 'Target model is required');
   this.keyTo = definition.keyTo;
+  this.typeTo = definition.typeTo;
+  if (!this.typeTo) {
+    assert(this.modelTo, 'Target model is required');
+  }
   this.modelThrough = definition.modelThrough;
   this.keyThrough = definition.keyThrough;
   this.multiple = (this.type !== 'belongsTo' && this.type !== 'hasOne');
@@ -97,14 +100,18 @@ RelationDefinition.prototype.toJSON = function () {
  * @param {Object} filter (where, order, limit, fields, ...)
  */
 RelationDefinition.prototype.applyScope = function(modelInstance, filter) {
+  filter.where = filter.where || {};
+  if (this.type !== 'belongsTo' && typeof this.typeTo === 'string') {
+    filter.where[this.typeTo] = this.modelFrom.modelName; // polymorphic
+  }
   if (typeof this.scope === 'function') {
     var scope = this.scope.call(this, modelInstance, filter);
+  } else {
+    var scope = this.scope;
+  }
   if (typeof scope === 'object') {
     mergeQuery(filter, scope);
   }
-  } else if (typeof this.scope === 'object') {
-    mergeQuery(filter, this.scope);
-  }
 };
 
 /**
@@ -124,6 +131,9 @@ RelationDefinition.prototype.applyProperties = function(modelInstance, target) {
       target[key] = modelInstance[k];
     }
   }
+  if (this.type !== 'belongsTo' && typeof this.typeTo === 'string') {
+    target[this.typeTo] = this.modelFrom.modelName; // polymorphic
+  }
 };
 
 /**
@@ -350,10 +360,20 @@ RelationDefinition.hasMany = function hasMany(modelFrom, modelTo, params) {
       modelTo = lookupModel(modelFrom.dataSource.modelBuilder.models, modelToName);
     }
   }
+  
   var relationName = params.as || i8n.camelize(modelTo.pluralModelName, true);
   var fk = params.foreignKey || i8n.camelize(thisClassName + '_id', true);
 
   var idName = modelFrom.dataSource.idName(modelFrom.modelName) || 'id';
+  var typeTo;
+  
+  if (typeof params.polymorphic === 'string') {
+    fk = i8n.camelize(params.polymorphic + '_id', true);
+    var typeTo = i8n.camelize(params.polymorphic + '_type', true);
+    if (!params.through) {
+      modelTo.dataSource.defineProperty(modelTo.modelName, typeTo, { type: 'string' });
+    }
+  }
   
   var definition = new RelationDefinition({
     name: relationName,
@@ -361,6 +381,7 @@ RelationDefinition.hasMany = function hasMany(modelFrom, modelTo, params) {
     modelFrom: modelFrom,
     keyFrom: idName,
     keyTo: fk,
+    typeTo: typeTo,
     modelTo: modelTo,
     multiple: true,
     properties: params.properties,
@@ -378,6 +399,8 @@ RelationDefinition.hasMany = function hasMany(modelFrom, modelTo, params) {
 
   if (!params.through) {
     // obviously, modelTo should have attribute called `fk`
+    // for polymorphic relations, it is assumed to share the same fk type for all
+    // polymorphic models
     modelTo.dataSource.defineForeignKey(modelTo.modelName, fk, modelFrom.modelName);
   }
 
@@ -797,8 +820,8 @@ HasManyThrough.prototype.remove = function (acInst, done) {
  * 
  */
 RelationDefinition.belongsTo = function (modelFrom, modelTo, params) {
-  params = params || {};
+  var typeTo, params = params || {};
-  if ('string' === typeof modelTo) {
+  if ('string' === typeof modelTo && !params.polymorphic) {
     params.as = modelTo;
     if (params.model) {
       modelTo = params.model;
@@ -808,24 +831,43 @@ RelationDefinition.belongsTo = function (modelFrom, modelTo, params) {
     }
   }
   
+  if (params.polymorphic) {
+    var polymorphic = modelTo;
+    modelTo = null; // will lookup dynamically
+    
+    var idName = params.idName || 'id';
+    var relationName = params.as || i8n.camelize(polymorphic, true);
+    var fk = i8n.camelize(polymorphic + '_id', true);
+    var typeTo = i8n.camelize(polymorphic + '_type', true);
+    
+    if (typeof params.idType === 'string') { // explicit key type
+      modelFrom.dataSource.defineProperty(modelFrom.modelName, fk, { type: params.idType });
+    } else { // try to use the same foreign key type as modelFrom
+      modelFrom.dataSource.defineForeignKey(modelFrom.modelName, fk, modelFrom.modelName);
+    }
+    
+    modelFrom.dataSource.defineProperty(modelFrom.modelName, typeTo, { type: 'string' });
+  } else {
     var idName = modelFrom.dataSource.idName(modelTo.modelName) || 'id';
     var relationName = params.as || i8n.camelize(modelTo.modelName, true);
     var fk = params.foreignKey || relationName + 'Id';
     
+    modelFrom.dataSource.defineForeignKey(modelFrom.modelName, fk, modelTo.modelName);
+  }
+  
   var relationDef = modelFrom.relations[relationName] = new RelationDefinition({
     name: relationName,
     type: RelationTypes.belongsTo,
     modelFrom: modelFrom,
     keyFrom: fk,
     keyTo: idName,
+    typeTo: typeTo,
     modelTo: modelTo,
     properties: params.properties,
     scope: params.scope,
     options: params.options
   });
   
-  modelFrom.dataSource.defineForeignKey(modelFrom.modelName, fk, modelTo.modelName);
-
   // Define a property for the scope so that we have 'this' for the scoped methods
   Object.defineProperty(modelFrom.prototype, relationName, {
     enumerable: true,
@@ -835,7 +877,9 @@ RelationDefinition.belongsTo = function (modelFrom, modelTo, params) {
       var relationMethod = relation.related.bind(relation);
       relationMethod.create = relation.create.bind(relation);
       relationMethod.build = relation.build.bind(relation);
+      if (relationDef.modelTo) {  
         relationMethod._targetClass = relationDef.modelTo.modelName;
+      }
       return relationMethod;
     }
   });
@@ -894,7 +938,9 @@ BelongsTo.prototype.build = function(targetModelData) {
  */
 BelongsTo.prototype.related = function (refresh, params) {
   var self = this;
+  var modelFrom = this.definition.modelFrom;
   var modelTo = this.definition.modelTo;
+  var typeTo = this.definition.typeTo;
   var pk = this.definition.keyTo;
   var fk = this.definition.keyFrom;
   var modelInstance = this.modelInstance;
@@ -911,9 +957,24 @@ BelongsTo.prototype.related = function (refresh, params) {
     cachedValue = self.getCache();
   }
   if (params instanceof ModelBaseClass) { // acts as setter
+    modelTo = params.constructor;
     modelInstance[fk] = params[pk];
+    if (typeTo) modelInstance[typeTo] = params.constructor.modelName;
     self.resetCache(params);
   } else if (typeof params === 'function') { // acts as async getter
+    
+    if (typeTo && !modelTo) {
+      var modelToName = modelInstance[typeTo];
+      if (typeof modelToName !== 'string') {
+        throw new Error('Polymorphic model not found: `' + typeTo + '` not set');
+      }
+      modelToName = modelToName.toLowerCase();
+      modelTo = lookupModel(modelFrom.dataSource.modelBuilder.models, modelToName);
+      if (!modelTo) {
+        throw new Error('Polymorphic model not found: `' + modelToName + '`');
+      }
+    }
+    
     var cb = params;
     if (cachedValue === undefined) {
       var query = {where: {}};

lib/relations.js

@@ -161,3 +161,7 @@ RelationMixin.hasAndBelongsToMany = function hasAndBelongsToMany(modelTo, params
 RelationMixin.hasOne = function hasMany(modelTo, params) {
   RelationDefinition.hasOne(this, modelTo, params);
 };
+
+RelationMixin.belongsToPolymorphic = function belongsToPolymorphic(polymorphic, params) {
+  RelationDefinition.belongsToPolymorphic(this, polymorphic, params);
+};

test/relations.test.js

@@ -3,6 +3,7 @@ var should = require('./init.js');
 
 var db, Book, Chapter, Author, Reader;
 var Category, Product;
+var Picture;
 
 describe('relations', function () {
 
@@ -527,6 +528,149 @@ describe('relations', function () {
   
   });
   
+  describe('polymorphic hasMany', function () {
+    before(function (done) {
+      db = getSchema();
+      Picture = db.define('Picture', {name: String});
+      Author = db.define('Author', {name: String});
+      Reader = db.define('Reader', {name: String});
+
+      db.automigrate(function () {
+        Picture.destroyAll(function () {
+          Author.destroyAll(function () {
+            Reader.destroyAll(done);
+          });
+        });
+      });
+    });
+
+    it('can be declared', function (done) {
+      Author.hasMany(Picture, { polymorphic: 'imageable' });
+      Reader.hasMany(Picture, { polymorphic: 'imageable' });
+      Picture.belongsTo('imageable', { polymorphic: true });
+      db.automigrate(done);
+    });
+    
+    it('should create polymorphic relation - author', function (done) {
+      Author.create({ name: 'Author 1' }, function (err, author) {
+        author.pictures.create({ name: 'Author Pic' }, function (err, p) {
+          should.not.exist(err);
+          should.exist(p);
+          p.imageableId.should.equal(author.id);
+          p.imageableType.should.equal('Author');
+          done();
+        });
+      });
+    });
+    
+    it('should create polymorphic relation - reader', function (done) {
+      Reader.create({ name: 'Reader 1' }, function (err, reader) {
+        reader.pictures.create({ name: 'Reader Pic' }, function (err, p) {
+          should.not.exist(err);
+          should.exist(p);
+          p.imageableId.should.equal(reader.id);
+          p.imageableType.should.equal('Reader');
+          done();
+        });
+      });
+    });
+    
+    it('should find polymorphic items - author', function (done) {
+      Author.findOne(function (err, author) {
+        author.pictures(function (err, pics) {
+          should.not.exist(err);
+          pics.should.have.length(1);
+          pics[0].name.should.equal('Author Pic');
+          done();
+        });
+      });
+    });
+    
+    it('should find polymorphic items - reader', function (done) {
+      Reader.findOne(function (err, reader) {
+        reader.pictures(function (err, pics) {
+          should.not.exist(err);
+          pics.should.have.length(1);
+          pics[0].name.should.equal('Reader Pic');
+          done();
+        });
+      });
+    });
+    
+    it('should find the inverse of polymorphic relation - author', function (done) {
+      Picture.findOne({ where: { name: 'Author Pic' } }, function (err, p) {
+        should.not.exist(err);
+        p.imageableType.should.equal('Author');
+        p.imageable(function(err, imageable) {
+          should.not.exist(err);
+          imageable.should.be.instanceof(Author);
+          imageable.name.should.equal('Author 1');
+          done();
+        });
+      });
+    });
+    
+    it('should find the inverse of polymorphic relation - reader', function (done) {
+      Picture.findOne({ where: { name: 'Reader Pic' } }, function (err, p) {
+        should.not.exist(err);
+        p.imageableType.should.equal('Reader');
+        p.imageable(function(err, imageable) {
+          should.not.exist(err);
+          imageable.should.be.instanceof(Reader);
+          imageable.name.should.equal('Reader 1');
+          done();
+        });
+      });
+    });
+    
+    it('should include the inverse of polymorphic relation', function (done) {
+      Picture.find({ include: 'imageable' }, function (err, pics) {
+        should.not.exist(err);
+        pics.should.have.length(2);
+        pics[0].name.should.equal('Author Pic');
+        pics[0].imageable().name.should.equal('Author 1');
+        pics[1].name.should.equal('Reader Pic');
+        pics[1].imageable().name.should.equal('Reader 1');
+        done();
+      });
+    });
+    
+    it('should assign a polymorphic relation', function(done) {
+      Author.create({ name: 'Author 2' }, function(err, author) {
+        var p = new Picture({ name: 'Sample' });
+        p.imageable(author); // assign
+        p.imageableId.should.equal(author.id);
+        p.imageableType.should.equal('Author');
+        p.save(done);
+      });
+    });
+    
+    it('should find polymorphic items - author', function (done) {
+      Author.findOne({ where: { name: 'Author 2' } }, function (err, author) {
+        author.pictures(function (err, pics) {
+          should.not.exist(err);
+          pics.should.have.length(1);
+          pics[0].name.should.equal('Sample');
+          done();
+        });
+      });
+    });
+    
+    it('should find the inverse of polymorphic relation - author', function (done) {
+      Picture.findOne({ where: { name: 'Sample' } }, function (err, p) {
+        should.not.exist(err);
+        p.imageableType.should.equal('Author');
+        p.imageable(function(err, imageable) {
+          should.not.exist(err);
+          imageable.should.be.instanceof(Author);
+          imageable.name.should.equal('Author 2');
+          done();
+        });
+      });
+    });
+    
+  });
+
   describe('belongsTo', function () {
     var List, Item, Fear, Mind;