fix(model): sum returns zero when empty matching (#9984)

lib/model.js

@@ -1958,7 +1958,12 @@ class Model {
     Utils.mapOptionFieldNames(options, this);
     options = this._paranoidClause(this, options);
 
-    return this.QueryInterface.rawSelect(this.getTableName(options), options, aggregateFunction, this);
+    return this.QueryInterface.rawSelect(this.getTableName(options), options, aggregateFunction, this).then( value => {
+      if (value === null) {
+        return 0;
+      }
+      return value;
+    });;
   }
 
   /**

lib/query-interface.js

@@ -1136,7 +1136,9 @@ class QueryInterface {
         const dataType = options.dataType;
 
         if (dataType instanceof DataTypes.DECIMAL || dataType instanceof DataTypes.FLOAT) {
-          result = parseFloat(result);
+          if (!_.isNull(result)) {
+            result = parseFloat(result);
+          }
         } else if (dataType instanceof DataTypes.INTEGER || dataType instanceof DataTypes.BIGINT) {
           result = parseInt(result, 10);
         } else if (dataType instanceof DataTypes.DATE) {

test/integration/model/sum.test.js

+'use strict';
+
+const chai = require('chai'),
+  expect = chai.expect,
+  Support = require('../support'),
+  DataTypes = require('../../../lib/data-types');
+
+describe(Support.getTestDialectTeaser('Model'), () => {
+  beforeEach(function() {
+    this.Payment = this.sequelize.define('Payment', {
+      amount: DataTypes.DECIMAL,
+      mood: {
+        type: DataTypes.ENUM,
+        values: ['happy', 'sad', 'neutral']
+      }
+    });
+
+    return this.sequelize.sync({force: true}).then(() => {
+      return this.Payment.bulkCreate([
+        {amount: 5, mood: 'neutral'},
+        {amount: -5, mood: 'neutral'},
+        {amount: 10, mood: 'happy'},
+        {amount: 90, mood: 'happy'}
+      ]);
+    });
+  });
+
+  describe('sum', () => {
+
+    it('should sum without rows', function() {
+      return expect(this.Payment.sum('amount', {where: {mood: 'sad'}})).to.eventually.be.equal(0);
+    });
+
+    it('should sum when is 0', function() {
+      return expect(this.Payment.sum('amount', {where: {mood: 'neutral'}})).to.eventually.be.equal(0);
+    });
+
+    it('should sum', function() {
+      return expect(this.Payment.sum('amount', {where: {mood: 'happy'}})).to.eventually.be.equal(100);
+    });
+  });
+});