Rastalamm Rastalamm - 27 days ago 20
Javascript Question

Add Property to Object that is returned by Sequelize FindOne

I am trying to add a property to a sequelize instance before passing it back to the client.

router.get('/cats/1', function (req, res) {
Cat.findOne({where: {id: 1}})
.then(function (cat) {
// cat exists and looks like {id: 1}
cat.name = "Lincoln";
// console.log of cat is {id: 1, name: Lincoln}
res.json(cat);
});
});


The client only see's
{id: 1}
and not the newly added key.


  • What is going on here?

  • What type of Object is returned by Sequelize?

  • How can I add new properties to my Cats and send them back?


Answer

The Sequelize Model class (of which your cats are instances) has a toJSON() method which res.json will presumably use to serialise your cats. The method returns the result of Model#get() (https://github.com/sequelize/sequelize/blob/95adb78a03c16ebdc1e62e80983d1d6a204eed80/lib/model.js#L3610-L3613), which only uses attributes defined on the model. If you want to be able to set the cats name, but not store names in the DB, you can use a virtual column when defining your cat model:

sequelize.define('Cat', {
  // [other columns here...]
  name: Sequelize.VIRTUAL
});

Alternatively, if you don't want to add properties to the model definition:

cat = cat.toJSON(); // actually returns a plain object, not a JSON string
cat.name = 'Macavity';
res.json(cat);
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