Type safety checks

Summary

In this lesson, we explore type safety checks in Waterline and Sails.js. Sails enforces type validation on model attributes using five supported data types: string, number, boolean, ref, and json. These types ensure that data stored in the database matches expected formats. The lesson demonstrates how each type works and provides a practical example of defining attributes in a User model, creating records, and inspecting stored data in PostgreSQL.

Transcript

Alright, so we're going to talk about type safety checks in both Waterline and Sails. You might have seen a little bit of this in previous lessons, but in this lesson, we're going to dive fully into it.

Let’s open up our User model that we've been working on. You’ll notice the type property in our attributes. By default, Sails and Waterline support five basic data types, and every attribute must have one of these. This type property is the only mandatory attribute definition in a model.

Now, let’s go over the five supported types:

• String – Used for text data.

• Number – Used for numerical values, including integers and decimals.

• Boolean – Stores either true or false.

• Ref – Can hold any value except undefined. This type is rarely used unless you need specific database behaviors.

• JSON – Accepts any JSON-serializable value, including numbers, strings, arrays, and objects. Databases like PostgreSQL and MongoDB store these efficiently.

Now, let's modify our User model to include some of these data types:

• isAdmin (Boolean) – Indicates whether the user is an admin.

• petName (Ref) – Stores the name of the user's pet.

• favoriteFrameworks (JSON) – Holds an array of frameworks the user prefers.

Next, let’s create a user record using these attributes. We'll add a record for Albus Dumbledore:

await User.create({
  firstName: 'Albus',
  lastName: 'Dumbledore',
  age: 300,
  petName: 'Fawkes',
  favoriteFrameworks: ['Sails', 'Vue']
}).fetch();

Since isAdmin is a Boolean and we didn’t provide a value, it defaults to false. If we check the database using a tool like Beekeeper, we can see how these values are stored.

• favoriteFrameworks is stored as a JSON array.

• petName is treated as text because ref allows any value except undefined.

• isAdmin defaults to false since we didn't explicitly set it.

To recap, type safety in Sails.js ensures that data adheres to predefined formats, preventing unexpected errors. Every model attribute must have a type (string, number, boolean, ref, or json), making type definitions a fundamental aspect of Sails models.