05hooks.md

Hooks

Hooks allow us to perform actions at different points throughout the life cycle of a model. For example, we could do something before an item is updated or after an item is created.

Sequelize supports many types of hooks. Full list in documentation

Example: normalize tags using beforeCreate

If we want all of our tags to be stored in all caps we could use a beforeCreate hook. This way if someone adds a tag Taco it will be stored as TACO and all of our tags will be the same.

//in models/tag.js -- tag model

//... some other model code above
hooks: {
  beforeCreate: function(tag, options, cb) {

    //take the tag name and capitalize it
    tag.name = tag.name.toUpperCase();

    //pass the updated tag object back
    cb(null, tag);
  }
}
//... some other model code below

Another way: addHook() method Inside the module.exports object in tag.js but before the return tag:

// some other model code 

  tag.addHook('beforeCreate', (pendingTag, options)=>{
    tag.name = tag.name.toUpperCase();
  })

  return tag;

};

We can use beforeCreate hook to automatically hash a user's password before it is created (AKA before the data is inserted into the database).