Simplifying State Management in Modern Web Applications

Introduction to State Management

State management is a crucial aspect of building modern web applications. As applications grow in complexity, it’s essential to have a straightforward and simplified approach to managing state in a centralized and consistent way.

What are Reactive Variables?

Reactive variables provide a flexible and powerful tool for managing local state within a JavaScript framework application. They allow you to read and modify local data anywhere within your application, without the need for a GraphQL operation.

Creating a Reactive Variable

Apollo Client provides a makeVar() method that can be used to create a reactive variable. The makeVar method takes a single argument, which is the initial value of the reactive variable.

import { makeVar } from '@apollo/client';

const name = makeVar('Mark Andrews');

Using Reactive Variables to Read Local Data

To read the current value of a reactive variable, simply call the function that was returned by the makeVar method without any arguments.

console.log(name()); // Output: Mark Andrews

Using Field Policies and Local-Only Fields to Read Local Data

You can also read data from a reactive variable by using the GraphQL useQuery syntax, with the @client directive.

import { useQuery, gql } from '@apollo/client';

const GET_NAME = gql`
  query GetName {
    name @client
  }
`;

const { data } = useQuery(GET_NAME);
console.log(data.name); // Output: Mark Andrews

Using Reactive Variables to Modify Local Data

To modify the current value of a reactive variable, simply call the function that was returned by the makeVar method with a single argument, which is the new value.

name('John Doe');
console.log(name()); // Output: John Doe

Reacting to Reactive Variable Data Changes with useReactiveVar

The useReactiveVar hook allows React components to directly include the values of reactive variables in their state, without the need to wrap them in a query.

import { useReactiveVar } from '@apollo/client';

function MyComponent() {
  const name = useReactiveVar(nameVar);
  return (

  );
}

The Power of Reactive Variables

Reactive variables and field policies are essential aspects of Apollo Client’s state management capabilities. They provide a powerful solution for managing complex state on the client side, and are sure to play a central role in the future of web development.