State management is easy - Introduction to MobX

State is the heart of each application and there is no quicker way to create buggy, unmanageable applications then by producing inconsistent state. Hence many state management solutions try to restrict the ways in which you can modify state, for example by making state immutable. But this introduces new problems; data needs to be normalized, referential integrity can no longer be guaranteed and it becomes next to impossible to use powerful concepts like prototypes.

At Mendix these restrictions where unacceptable and so MobX was born. MobX makes state management simple again by addressing the root issue: it makes it impossible to produce an inconsistent state. This makes state management simple and scalable again.

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1. State Management Is Easy
   Michel Weststrate
   @mweststrate
   Mendix
   React Amsterdam 2016
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2. The DOM Was Hard...
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3. State Management Is Hard
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4. Redux: Simple & Elegant Concept
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5. Pulls Amazing Tricks
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6. New Things To Learn!
   Reducers
   Immutables
   Denormalization
   Connect
   Selectors
   Smart & Dumb
   components
   Thunks & Sagas
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7. MobX - No Pedaling
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10. MobX
    1. The Idea
    2. Simple
    3. Fast
    4. Scalable
    5. Questions
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11. Why Is State Management Hard?
    Σ
    State
    Aggregates Lookup tables Server Storage UI
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    affects:
    

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12. 1. State Should Be Minimally Defined
    No Caching
    No Data Duplication
    No Cascading State Changes
    Don't worry about how the app should react to state!
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13. 2. Everything Should Be Derived
    Automatically
    Define derivations & reactions
    MobX ensures efficiency & consistency
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14. Actions State Views
    Modify Updates
    Σ
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15. Simple
    jsbin.com/hukiso/edit?js,output
    github.com/mweststrate/mobx-contacts-list/
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18. @observable / @computed
    class Contact {
    @observable title = "Mr"
    @observable firstName = "Michel"
    @observable lastName = "Moped"
    @observable picture = {
    thumbnail: null,
    medium: null,
    large: null
    }
    @observable tags = []
    @computed get displayName() {
    const cfl = capitalizeFirstLetter
    return `${cfl(this.title)}. ${cfl(this.firstName)} ${cfl(this.lastName)}`
    }
    }
    class Tag{
    id;
    @observable name = "Favorites"
    }
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19. observer
    const ContactEntryView = observer(({contact, viewState}) =>
    className={viewState.selection === contact ? 'selected' : null}
    onClick={() => viewState.selectContact(contact) }
    >
    
    {contact.displayName}
    {contact.tags.map(tag => type="button"
    value={tag.name}
    key={tag.id}
    onClick={() => viewState.selectTag(tag)}
    />)}
    
    )
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20. observer
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21. @observer
    @observer
    export class ContactsOverview extends Component {
    render() {
    const {contactStore, viewState} = this.props;
    return
    label="Add Contact"
    onClick={() => contactStore.createRandomContact() }
    />
    { contactStore.pendingRequestCount > 0
    ?
    : null
    }
    { contactStore.contacts.map(contact =>
    contact={contact}
    key={contact.id}
    viewState={viewState}
    />
    ) }
    
    }
    }
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22. Actions
    createRandomContact() {
    this.pendingRequestCount++
    superagent.get('https://randomuser.me/api/').end((error, data) => {
    const contact = new Contact(data)
    this.contacts.push(contact)
    this.pendingRequestCount--
    }
    }
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23. @observable
    enables MobX to observe your data
    @observer
    MobX ensures that this component is consistent with the state
    @computed
    MobX ensures that this value is consistent with the state
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24. Fast
    Numbers!
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26. Such Fast
    Only track data which is accessed in last render
    Minimizes amount of computations
    PureRenderMixin
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27. Scalable
    MobX @ Mendix
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28. ~500 classes
    apidocs.mendix.com/modelsdk/
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30. Demo
    link
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32. Scalable
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    Minimal state
    Graphs: natural mental model
    Simple code
    Architectural freedom
    Third party friendly
    actions? State views?
    Modify Updates
    

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33. State Management Is Simple!
    Questions? #reactamsterdam @mweststrate
    "I am putting my eggs into React and MobX basket. So far building two huge React apps I haven't
    had any reason to regret it."
    "It's almost ridiculous how simple and powerful MobX + React is"
    "Working with #mobx is basically a continuous loop of me going “this is way too simple, it definitely
    won’t work” only to be proven wrong"
    "Try react-mobx with es6 and you will love it so much that you will hug someone."
    "MobX compared to Redux feels like gravity gun compared to a wheelbarrow"
    "I used to be Angular guy, but seeing how observables play well with React,
    I would never go back to it."
    "I have built big app with MobX already and comparing to the one before that which was using
    Redux, it is simpler to read and much easier to reason about."
    "Cuts out much boilerplate and complexity."
    "The #mobx is the way I always want things to be! It's really surprising simple and fast! Totally
    awesome! Don't miss it!" 33
    

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