Redux Refactoring Patterns with @ngrx/platform

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Redux Refactoring Patterns @GregOnNet co-IT.eu GmbH We Empower Outstanding Business Solutions

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MY FRIEND OSCAR Meet Oscar 1. My Colleage 2. He works with 3. Passionated about Software Development

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MY FRIEND OSCAR Meet Oscar 1. …He is not an early morning person.

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Your Code Should Always Feel Like Home.

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@GregOnNet Gregor Woiwode CTO

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co-IT.eu GmbH We Empower Outstanding Business Solutions “ Collect your questions for the Q&A session, please. @GregOnNet

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AGENDA Our Review With Oscar 1. Property Pattern 2. @ngrx/entity 3. @ngrx/router-store 4. selectors 5. ngrx-data

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export function reducer(state = initialState, action: NotesActions): State { switch (action.type) { case NotesActionTypes.CreateNoteSuccess: { return { ...state, notes: [...state.notes, action.payload], loaded: true, loading: false } } case NotesActionTypes.LoadNotesSuccess: { return { ...state, notes: ...action.payload, loaded: true, loading: false } /* ... */ Redundant Code

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/* ... */ case NotesActionTypes.LoadAdditionalNotesSuccess: { return { ...state, notes: [...state.notes, ...action.payload], loaded: true, loading: false } } case NotesActionTypes.DeleteSingleNoteSuccess: { return { ...state, notes: state.notes.filter(note => note.guid !== action.payload.guid), loaded: true, loading: false } } /* ... */ Remove By Filtering

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OSCAR‘S PROBLEM Large Switch-Case-Statements 1. Lot‘s of list operations we may not need every time 2. Hard to maintain 3. Less readable

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Property Pattern SIMPLIFY STATE MUTATIONS

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PROPERTY PATTERN Convert Collections To Dictionaries export interface State { notes: Note[]; } export interface State { notes: { [key: string]: Note }; } List to Object

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PROPERTY PATTERN Delete Single Object return { ...state, notes: state.notes.filter(note => note.guid !== action.payload.guid ) } const { [action.payload.guid]: deleted, ...withoutDeleted } = state.notes; return { ...state, notes: withoutDeleted, }

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MY FRIEND OSCAR Oscar asks… Maybe accessing data is more efficient. But the code complexity has increased. How can we benefit from this approach?

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PROPERTY PATTERN Review Less Collection Operations More Performant Operations Less Readable Code

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@ngrx/entity SIMPLIFY REDUCERS

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@ngrx/entity Entity State export interface State extends EntityState {} export interface State { ids: string[]; entities: { [id: string]: T }; } Leverages Property Pattern

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@ngrx/entity Entity Adapter import { createEntityAdapter } from '@ngrx/entity'; const adapter = createEntityAdapter(); The mighty helper

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@ngrx/entity Entity Mutators Operations for single objects and collections

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@ngrx/entity Simplify Mutations return adapter.removeOne( action.payload, state ); const { [action.payload.guid]: deleted, ...withoutDeleted } = state.notes; return { ...state, notes: withoutDeleted, } 1. Enusres Immutability 2. Applies State Mutation

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@ngrx/entity Entity Selectors const adapter = createEntityAdapter(); export const { selectAll, selectEntities, selectIds, selectTotal } = adapter.getSelectors();

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@ngrx/entity Use Entity Selectors export class NotesDashboardComponent { notes$: Observable; constructor(private store: Store) { this.notes$ = this.store.pipe(select(fromNotes.selectAll)); } }

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Demo ENTITY ADAPTER

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PROPERTY PATTERN Review Less Code Duplication Reusable Mutators & Selectors

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MY FRIEND OSCAR Oscar asks… @ngrx/entity is nice, thanks. Can we tidy up these Switch-Case-Statements now?

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createReducer SIMPLIFY REDUCER INFRASTRUCTURE

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CREATE REDUCER Switch-Case-Anatomy Infrastructure UI-Logic case: a case: b case: …

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CREATE REDUCER Factory Pattern To The Rescue const mutators: ActionHandlers = { [NotesActionTypes.CreateNote]: notes.addOne, [NotesActionTypes.LoadNotesSuccessful]: notes.addMany }; export function reducer(state = initialState, action) { return createReducer(mutators)(state, action); } Refer to last slide for the source

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Demo REMOVE SWITCH-CASE-STATEMENTS

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PROPERTY PATTERN Review Reduced Infrastructure Code Reducers do not need to be enhanced as Requirements change

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MY FRIEND OSCAR Oscar asks… Small things can have a great impact to quality. But wait since you are here…

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OSCAR‘S PROBLEM He thinks he breakse the Redux Pattern Shouldn’t the store be able to answer every question of a Component?

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SINGLE SOURCE OF TRUTH How to deal with location state? /* ... */ export class NoteDetailsComponent { note$: Observable; constructor( private route: ActivatedRoute, private store: Store) { this.note$ = this.route.params.pipe( switchMap(params => this.store.pipe(state => state.notes.entities[params.guid]) ) ); } }

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@ngrx/router-store SIMPLIFY LOCATION STATE HANDLING

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@ngrx/router-store Setup import { StoreRouterConnectingModule } from '@ngrx/router-store'; @NgModule({ imports: [ /* ... */ StoreRouterConnectingModule, ] /* ... */ }) export class AppModule {}

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@ngrx/router-store Types & Reducer Come For Free import * as fromRouter from '@ngrx/router-store'; export interface State { routerReducer: fromRouter.RouterReducerState; } export const reducers: ActionReducerMap = { routerReducer: fromRouter.routerReducer };

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@ngrx/router-store Enhance The State Tree Store Notes Router State provided by @ngrx/router-store

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@ngrx/router-store Access The Router State import { createFeatureSelector } from '@ngrx/store'; export const getRouterState = createFeatureSelector('routerReducer');

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@ngrx/router-store Read Router State export const currentDetails = createSelector( getEntities, getRouterState, (notes, router) => entities[router.state.params.guid] ); RoutingComponent select

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@ngrx/router-store The Reducer‘s Outcome Let’s traverse through the whole state tree! Of Cause Not!

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Demo COMPRESS ROUTER STATE

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PROPERTY PATTERN Review Store is Single Source of Truth again Reduced Complexity of Component Component does not rely on ActivatedRoute anymore

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MY FRIEND OSCAR Oscar asks… This feels more correct than before, thanks. Wait! There is one very last thing…

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OSCAR‘S PROBLEM I Can See A Revenent Pattern…. We only do CRUD operations. Do we need to repeat ourselves for every entity?

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“ I see reccurring patterns…

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Looking for the right answer…

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ngrx-data SIMPLIFY STORE USING CONVENTIONS

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Know, Can Do… Put Your Know-How Into Action!

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ngrx-data Overview Actions Reducers Effects Data Services Dynamically sets up…

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Configure an entity export const entityMetadata: EntityMetadataMap = { Note: { selectId: (note: Note) => note.guid } }; export const pluralNames = { Note: 'Notes' }; ngrx-data

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Setup Entity Cache ngrx-data NgrxDataModule.forRoot({ entityMetadata, pluralNames }),

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ngrx-data Data Services import { Note } from '../../models/note'; @Injectable() export class NotesBoard extends EntityCollectionServiceBase { constructor(entityServiceFactory: EntityCollectionServiceFactory) { super('Note', entityServiceFactory); } }

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Convention Based Data Services ngrx-data localhost:4200/api/notes/ root entityName parameters

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ngrx-data Built-In Functions Of A Data Service Mutators & Selectors for the given entity.

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Demo CONFIGURE NGRX-DATA

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ngrx-data Get Rid Of Unneeded Files Delete Delete Custom Configuration

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PROPERTY PATTERN Review Less Files to maintain Scales good for many entities Highly Configurable Handles Loading State automatically High Learning Curve Lot‘s of things happen behind the scenes

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co-IT.eu GmbH We Empower Outstanding Business Solutions Thank you! @GregOnNet e.co-it.eu/dwx18-gift e.co-it.eu/dwx18-ng

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