Fix(#4702): Instance returns this on all paths

changelog.md

 # Future
 # Future
 - [FIXED] calling Model.update() modifies passed values  [#4520](https://github.com/sequelize/sequelize/issues/4520)
 - [FIXED] calling Model.update() modifies passed values  [#4520](https://github.com/sequelize/sequelize/issues/4520)
+- [FIXED] Instance can be chained on .set() and other methods [#4702](https://github.com/sequelize/sequelize/issues/4702)
 
 
 # 3.15.0
 # 3.15.0
 - [ADDED] Improve support for pg range type to handle unbound ranges, +/-infinity bounds and empty ranges
 - [ADDED] Improve support for pg range type to handle unbound ranges, +/-infinity bounds and empty ranges

lib/instance.js

@@ -314,7 +314,7 @@ Instance.prototype.set = function(key, value, options) { // testhint options:non
       if (this.$options && this.$options.include && this.$options.includeNames.indexOf(key) !== -1) {
       if (this.$options && this.$options.include && this.$options.includeNames.indexOf(key) !== -1) {
         // Pass it on to the include handler
         // Pass it on to the include handler
         this._setInclude(key, value, options);
         this._setInclude(key, value, options);
-        return;
+        return this;
       } else {
       } else {
         // Bunch of stuff we won't do when its raw
         // Bunch of stuff we won't do when its raw
         if (!options.raw) {
         if (!options.raw) {
@@ -327,17 +327,17 @@ Instance.prototype.set = function(key, value, options) { // testhint options:non
                 this.changed(key.split('.')[0], true);
                 this.changed(key.split('.')[0], true);
               }
               }
             }
             }
-            return;
+            return this;
           }
           }
 
 
           // If attempting to set primary key and primary key is already defined, return
           // If attempting to set primary key and primary key is already defined, return
           if (this.Model._hasPrimaryKeys && originalValue && this.Model._isPrimaryKey(key)) {
           if (this.Model._hasPrimaryKeys && originalValue && this.Model._isPrimaryKey(key)) {
-            return;
+            return this;
           }
           }
 
 
           // If attempting to set read only attributes, return
           // If attempting to set read only attributes, return
           if (!this.isNewRecord && this.Model._hasReadOnlyAttributes && this.Model._isReadOnlyAttribute(key)) {
           if (!this.isNewRecord && this.Model._hasReadOnlyAttributes && this.Model._isReadOnlyAttribute(key)) {
-            return;
+            return this;
           }
           }
 
 
           // Convert date fields to real date objects
           // Convert date fields to real date objects
@@ -349,7 +349,7 @@ Instance.prototype.set = function(key, value, options) { // testhint options:non
               originalValue = new Date(originalValue);
               originalValue = new Date(originalValue);
             }
             }
             if (originalValue && value.getTime() === originalValue.getTime()) {
             if (originalValue && value.getTime() === originalValue.getTime()) {
-              return;
+              return this;
             }
             }
           }
           }
         }
         }
@@ -693,8 +693,8 @@ Instance.prototype.save = function(options) {
           return result;
           return result;
         })
         })
         .tap(function() {
         .tap(function() {
-          if (!wasNewRecord) return;
-          if (!self.$options.include || !self.$options.include.length) return;
+          if (!wasNewRecord) return self;
+          if (!self.$options.include || !self.$options.include.length) return self;
 
 
           // Nested creation for HasOne/HasMany/BelongsToMany relations
           // Nested creation for HasOne/HasMany/BelongsToMany relations
           return Promise.map(self.$options.include.filter(function (include) {
           return Promise.map(self.$options.include.filter(function (include) {