DECIMAL values are now Strings with mysql2

What are you doing?

Hi I recently needed to upgrade to v4.0.0-2 to get a critical bug fix. In the process of the upgrade, I needed to also bump to mysql2. I’m getting close to wrapping things up but I found something peculiar with the way that DECIMALs are now handled.

Per this issue in the mysql2 project, DECIMAL is now returned as a String not a number. Their proposed fix is for the consumer to apply a typeParser to the mysql2 connection.

Here is a simple test that fails:

it('should parse the decimal as a number', function(){
      const Model = this.sequelize.define('model', {
        jewelPurity: Sequelize.DECIMAL(10, 2)
      });

      const sampleData = {
        id: 1,
        jewelPurity: 133.7,
      };

      return Model.sync({ force: true }).then(() => {
        return Model.create(sampleData);
      }).then(() => {
        return Model.findById(1);
      }).then(user => {
        debugger
        expect(user.jewelPurity).to.not.be.string;
        expect(user.jewelPurity).to.be.eql(sampleData.jewelPurity);
      });
 });

What do you expect to happen?

I expect the numerical fields to continue to behave consistently after the upgrade.

What is actually happening?

I get back strings which is surprising.

Dialect: mysql Database version: 5.6 Sequelize version: 4.0.0-2

[miselaytes-anton]

Hi, in my case I do sequelize.query('select sum(steps) as steps from measurement' ) where steps is steps: {type: DataTypes.INTEGER} and get steps as a string, while I prefer to have it as an integer.

Is it safe to fix it like below?

const sequelize = new Sequelize(config.sql.database, config.sql.username, config.sql.password, {
  dialect: 'mysql',
  dialectOptions: {decimalNumbers: true}
});

[dengue8830]

this is a serius problem for javascript in the server 😕

1. if the problem is inherent of the javascript number representation, a downgrade to sequelize v3 or the dialect trick is not a solution because this is a problem that has been there forever, am i right?

1.1) if i have sequelize v3, my extra-big numbers will be rounded with no solution?

1.2) and the dialect trick dialectOptions: { decimalNumbers: true } is a bad idea too because it’s like use v3, the extra-big numbers will be rounded?

1. The best solution is use FLOAT for numbers that we know that can be successfully parsed to a js number, and DOUBLE with a manual parse to a third lib that handles extra-big numbers, am i right?

something like this:

let company = await Company.findById(1);
company.extrabignumber = new Decimal(company.extrabignumber);
company.extrabignumber.add(99999999999999);

2.1) but how to save this extra big numbers?

company.extrabignumber = company.extrabignumber.toString();
company.save(); // could this save the number successfully ?

1. Could sequelize include some lib to handle this numbers and prevent the manual process described above?

so, sequelize v4 doesn’t gave us a new problem, only shows us a problem that has been there for a long time. Can somebody help with this doubts?