Application Overview

State Management

What is MobX State Tree?

What will you learn in this course?

Will this course be for you?

Introduction

The Tree in MobX State Tree

The Store Model

Types

Model Actions

Model Views

Snapshots

Identifiers and References

Asynchronous Actions

Lifecycle Hooks

Concepts

Arrays in MobX State Tree

Maps

Nesting Stores

Optimistic Updates

Time Travel

Advanced Concepts

Overview of React and MobX State Tree

Context and Hooks

Observable

React

Overview

Building Voyager

mobx-state-tree

In this course, we will create a complete React Application with the state management handled by MobX State Tree, a state container system that is built on MobX, a functional reactive state library.

MobX State Tree will give your application a solid structure and foundation for large-scale applications and for small applications that are expected to scale rapidly. In comparison to Redux, MobX State Tree outstands it in performance with much less boilerplate. MobX is one of the most popular Redux alternatives and it's used by companies all over the world, including Netflix, Grow, IBM, DAZN, Baidu, and more.

During this course, you'll learn:

* Types in MobX State Tree.
* How to create the architecture of a centralized store.
* How to mutate the state via actions that could be asynchronous or not, depending on if we need to perform network requests to persist data into a database via GraphQL.
* Understanding snapshots and how we can benefit from them to time-travel if a network request fails.
* Understanding how MobX State Tree makes use of observable properties and observers.
* Leveraging re-renders in your React Application to MobX observers for better performance optimizations.

By the end of this course, you will have the knowledge and skills that it takes to build a real-world, production-level React Application with a State Management with top-notch performance that can scale with ease.

In this course, we'll show you how to build a React App with MobX State Tree.

The newline Guide to Building a React App with MobX State Tree

How to integrate MobX State Tree within your React App

Dealing with asynchronous flows and time travel to preserve state on networking errors

How to create a scalable store using MobX State Tree

---
title: Model Actions
slug: model-actions-in-mobx-state-tree
description: Introduction to the model actions of MobX State Tree
role: "LESSON"
isPublicLesson: false
privateVideoUrl: https://fullstack.wistia.com/medias/19be51souj
---

# Model Actions in MobX State Tree

In MobX State Tree, models can only modify their properties by dispatching their own actions, or by actions in models higher up in their own tree.

Actions are defined by returning an object from the chainable `.actions` method. The initializer function is executed per instance, so that the `self` argument of the function is always bound to the current instance.

Let's extend the previous example by adding actions to the model so we can update the model data as we want.

```js { actualFilename=src/actions.js endChar=381 endLine=22 startChar=0 startLine=1 statedFilename=src/actions.js url=https&#x3A;//gitlab.com/fullstackio/books/newline-guide-to-building-a-react-app-with-mobx-state-tree/module_01/lesson_01.04/src/actions.js }
import { types } from "mobx-state-tree";

const UserStore = types
  .model("UserStore", {
    name: types.string,
    lastName: "Casillas",
    age: types.number,
  })
  // 1
  .actions((self) => ({
    // 2
    updateName(name) {
      self.name = name;
    },
    updateLastName(name) {
      self.lastName = name;
    },
    updateAge(age) {
      self.age = age;
    },
  }));
```

1.  `actions` method call that takes a function. In this case, `self` is the main and only argument to that function and references the model itself, allowing you to access its properties and other actions within this scope, and returning an object literal.
2.  Defining an action called `updateName` that takes a single argument that will be used to update the model's name property.

As we can see in the example above, a model's data can be changed within actions. If you ever try to modify a model's property or node without using an action, it will throw an exception.

## Considerations

Some things to consider when it comes to model actions:

1.  Model's properties or nodes cannot be modified without dispatching an action, otherwise it will throw an exception.
2.  It's recommended that action arguments are serializable.
3.  Actions can only modify models that belong to the (sub)tree on which they are invoked.
4.  `this` cannot be used inside actions. That's why you have the `self` argument that makes it safe to pass actions around without any binding issues or having to wrap them in arrow functions.

## Useful methods

There are some handy and useful methods when it comes to model actions, like:

-   `onAction`: listens to any action that is invoked on the model or any of its descendants.
-   `addMiddleware`: adds an interceptor function to any action invoked on the subtree of this model.
-   `applyAction`: invokes an action on the model.


Introduction to the model actions of MobX State Tree

Learn

The newline Guide to Building Your First GraphQL Server with Node and TypeScript

Teach

Amelia Wattenberger

Author of Fullstack D3

Community

The newline Guide to Building a React App with MobX State Tree

Module 1: Introduction

Introduction:

Start Here

Introduction: (0:42)

Application Overview

Introduction:

State Management

Introduction:

What is MobX State Tree?

Introduction:

What will you learn in this course?

Introduction:

Will this course be for you?

Module 2: Concepts

Lesson 1:

The Tree in MobX State Tree

Lesson 2: (1:44)

The Store Model

Lesson 3:

Types

Lesson 4: (2:38)

Model Actions

Lesson 5:

Model Views

Lesson 6:

Snapshots

Lesson 7:

Identifiers and References

Lesson 8:

Asynchronous Actions

Lesson 9:

Lifecycle Hooks

Module 3: Advanced Concepts

Lesson 1:

Arrays in MobX State Tree

Lesson 2:

Maps

Lesson 3:

Nesting Stores

Lesson 4:

Optimistic Updates

Lesson 5:

Time Travel

Module 4: React

Lesson 1:

Overview of React and MobX State Tree

Lesson 2:

Context and Hooks

Lesson 3:

Observable

Module 5: Building Voyager

Lesson 1:

Overview

Model Actions