fix(model): create instance with many-to-many association with extra column (#10034) (#10050)

lib/model.js

@@ -3809,7 +3809,8 @@ class Model {
           if (!this._options.include || !this._options.include.length) return this;
 
           // Nested creation for HasOne/HasMany/BelongsToMany relations
-          return Promise.map(this._options.include.filter(include => !(include.association instanceof BelongsTo)), include => {
+          return Promise.map(this._options.include.filter(include => !(include.association instanceof BelongsTo ||
+            include.parent && include.parent.association instanceof BelongsToMany)), include => {
             let instances = this.get(include.as);
 
             if (!instances) return Promise.resolve();
@@ -3831,8 +3832,21 @@ class Model {
                   const values = {};
                   values[include.association.foreignKey] = this.get(this.constructor.primaryKeyAttribute, {raw: true});
                   values[include.association.otherKey] = instance.get(instance.constructor.primaryKeyAttribute, {raw: true});
-                  // Include values defined in the scope of the association
+                  
+                  // Include values defined in the association
                   Object.assign(values, include.association.through.scope);
+                  if (instance[include.association.through.model.name]) {
+                    for (const attr of Object.keys(include.association.through.model.rawAttributes)) {
+                      if (include.association.through.model.rawAttributes[attr]._autoGenerated ||
+                        attr === include.association.foreignKey ||
+                        attr === include.association.otherKey ||
+                        typeof instance[include.association.through.model.name][attr] === undefined) {
+                        continue;
+                      }
+                      values[attr] = instance[include.association.through.model.name][attr];
+                    }
+                  }
+
                   return include.association.throughModel.create(values, includeOptions);
                 });
               } else {

test/integration/associations/belongs-to-many.test.js

@@ -1786,6 +1786,44 @@ describe(Support.getTestDialectTeaser('BelongsToMany'), () => {
             return ctx.worker.addTask(ctx.task);
           });
         });
+
+        it('should be able to create an instance along with its many-to-many association which has an extra column in the junction table', function() {
+          const Foo = this.sequelize.define('foo', { name: Sequelize.STRING });
+          const Bar = this.sequelize.define('bar', { name: Sequelize.STRING });
+          const FooBar = this.sequelize.define('foobar', { baz: Sequelize.STRING });
+          Foo.belongsToMany(Bar, { through: FooBar });
+          Bar.belongsToMany(Foo, { through: FooBar });
+
+          return this.sequelize.sync({force: true}).then(() => {
+            return Foo.create({
+              name: 'foo...',
+              bars: [
+                {
+                  name: 'bar...',
+                  foobar: {
+                    baz: 'baz...'
+                  }
+                }
+              ]
+            }, {
+              include: Bar
+            });
+          }).then(foo => {
+            expect(foo.name).to.equal('foo...');
+            expect(foo.bars).to.have.length(1);
+            expect(foo.bars[0].name).to.equal('bar...');
+            expect(foo.bars[0].foobar).to.not.equal(null);
+            expect(foo.bars[0].foobar.baz).to.equal('baz...');
+            
+            return Foo.findOne({ include: Bar });
+          }).then(foo => {
+            expect(foo.name).to.equal('foo...');
+            expect(foo.bars).to.have.length(1);
+            expect(foo.bars[0].name).to.equal('bar...');
+            expect(foo.bars[0].foobar).to.not.equal(null);
+            expect(foo.bars[0].foobar.baz).to.equal('baz...');
+          });
+        });
       });
 
       describe('set', () => {