Database Hooks (Mongoose or Sequelize)

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.

Most ORMs will support some form of hooks, including both Mongoose and Sequelize

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. The example below shows this code in Mongoose.

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

//... some other model code above

tagSchema.pre('save', function(next) {
  var tag = this
  tag.name = tag.name.toUpperCase();
  next();
});

//... some other model code below

We can use pre save hooks to automatically hash a users password before it is created (AKA before the data is inserted into the database).