Getters

As the name implies, in a Joystick app, a getter is a way to "get" data from a data source. Typically that data source is a database, but could also be a third-party API, a static file, etc. Ultimately, a getter is nothing more than a function being called with some helpful utilities and context added.

Getters are organized in your /api folder, in sub-directories with names related to the data being retrieved. For example, if we had a collection/table in our database called books, we'd want to define a folder like /api/books. Inside of that folder, we'd create a file for our getters at /api/books/getters.js, exporting an object from that file with all of our book-related getter definitions.

Defining a Getter

Following the above example, let's define a getter for retrieving some books from our database.

const getters = {
  books: {
    get: () => {
      return process.databases.mongodb.collection('books').find().toArray();
    }
  }
};

export default getters;

Above, we've defined a simple getter books. To do it, we assign books as a key on a parent object containing all of our book-related getters. To that key, we've assigned another object with a single method get(): the function on our getter that's responsible for retrieving data.

In this example, we're calling to our database and returning the query result directly from the getter.

Accessing input and context

When a getter is called (typically via the get() method imported from @joystick.js/ui or the api.get() method passed to a component's data function), input can be passed along with the request containing useful information like the ID of a specific item to retrieve, a category, etc.

const getters = {
  books: {
    get: (input = {}) => {
      return process.databases.mongodb.collection('books').find({
        category: input?.category,
      }).toArray();
    }
  }
};

export default getters;

If there's any input passed with a getter request, Joystick will pass it as the first argument to your get() function. Above, we anticipate a category being passed in the input and utilize it in our database query.

const getters = {
  books: {
    get: (input = {}, context = {}) => {
      return process.databases.mongodb.collection('books').find({
        category: input?.category,
        user_id: context?.user?._id,
      }).toArray();
    }
  }
};

export default getters;

In addition to input, as the second argument to your getter's get() function, a context object is passed with a few different sub-fields:

• req the inbound HTTP request related to the getter request.
• user if available, the currently logged in user.
• <database_provider> a connection to the database driver for one of your app's configured database providers (e.g., context.mongodb or context.postgresql).

Above, as an example, we've referenced the currently logged in user's _id field (if our user's database provider was a SQL database like PostgreSQL, we'd reference context.user.user_id) on the context object.

API Reference

get()

Function API

get(input: object, context: object) => any;

Arguments