Trong ng dng Angular, bn c th cung cp provider 2 cp : Module v Component/Directive. 
First, our shared module: Notice how we declare and export our pipes and directives as usual in the NgModules metadata, but we dont provide the service. Cn i vi cc kiu d liu primitive nh boolean, string, number, etc; chng ta cn @Inject bo cho Angular bit, v chng ta s config cc provider tng ng cho chng. DI trong Angular bao gm 3 thnh phn sau y: Injector: l mt object c cha cc API chng ta to cc instances ca cc ph thuc. Chng ta thay i code nh sau: V khi chy chng trnh chng ta c th inject ph thuc nh sau: Khi p dng Abstration, chng ta hon ton c th s dng tnh a hnh d dng thay i cc ph thuc. imports: N l mt mng cc module cn thit c s dng trong ng dng. Tuy nhin, c mt iu vn cha c tt cho lm, l cc module ch c load khi m ngi dng s dng n. y l mt ng dng email client nn module Email s c s dng rt rt thng xuyn. Scope ca nhng component (c khai bo trong thuc tnh declarations) ch c th s dng c trong ni b module . Trong Angular chng ta c kh nhiu module trong 1 ng dng vy chng ta phi import cc module theo cch nh th no? https://angular.io/docs/ts/latest/cookbook/dependency-injection.html, https://edwardthienhoang.wordpress.com/2015/03/30/tan-man-ve-dependency-injection/, https://blog.thoughtram.io/angular/2015/05/18/dependency-injection-in-angular-2.html, Download PDF:https://drive.google.com/file/d/0B-ux0B5az7XuNG9FaW5YVUJ6Nm8/view?usp=sharing. Chng ta s bt u nhm ln khi scope ca component/directive/pipe (mnh gi tt chung l component) s khng ging vi service. Nu module c import s dng cc service, chng ta ch nn import n 1 ln trong module chnh. Di y l mt on code trch ra t Angular Forms module validate mt field l required: Nh bn c th thy, Angular khai bo provider cn s dng n class khai bo ngay sau n. Sign up for Infrastructure as a Newsletter. , c module l AppModule c khai bo file src/app/app.module.ts: ng dng Angular c 2 loi Module l module gc v module chc nng. N cng c th c s dng bi cc Component trong mng Declarations. tag selector cho component ny l app-vidu01-component, khai bo component thuc module ModuleChucnangModule sa li m nh sau, np module ny vo AppModule th m file app.module.ts v thm ModuleChucnang vo phn declare, Nh vy Module chc nng np vo AppModule, hin th Component ca Module AppModule, y l cch preload tt c cc Module trong Angular app. Khi no nn import module no?
Let's register a Viblo Account to get more interesting posts. Vi cc ng dng nh, ch cn 1 module v chnh l module gc l . Nu module c import s dng cc component, chng ta s phi import vo cc module no chng ta mun s dng v scope ca component ch c scope locally. to ra mt module chng ta c th to th cng bng tay, hoc s dng Angular CLI bng c php, Feature Module: Gom cc component hoc service c lin quan n nhau hoc cng nm trong mt feature no thnh mt nhm, Vic tch ra cc module c mt tm nh hng rt ln n vic pht trin mt d n angular nu phn chia n hp l v khoa hc, mt d n s pht trin d dng, d bo tr, d tip cn. DigitalOcean makes it simple to launch in the cloud and scale up as you grow whether youre running one virtual machine or ten thousand. V d, trong ng dng email, chng ta c 2 lazy load modules: Settings module Cannot resolve all parameters for CPU(?). Khi to instance ca class CPU trong class Computer v gn cho property cpu, trong trng hp ca JavaScript, TypeScript l khi to trong hm to. Mnh va gii thiu vi cc bn cc kin thc c bn nht v Module trong Angular app mong rng bn c thm nhng kin thc hay v module v s p dng thnh cng trong d n ca mnh, https://medium.com/@cyrilletuzi/architecture-in-angular-projects-242606567e40, https://medium.com/@cyrilletuzi/understanding-angular-modules-ngmodule-and-their-scopes-81e4ed6f7407, https://hpphat.wordpress.com/2018/11/07/tim-hieu-ve-angular-module-va-tam-vuc-anh-huong-scope/?fbclid=IwAR12JQmGVxN3lBChWMr0BYhDq8znQRJf0ZwQeJpuazSsZplbwRv8WvMdwYM, https://viblo.asia/p/angular-cai-thien-hieu-nang-va-trai-nghiem-nguoi-dung-voi-lazy-loading-djeZ1BkRlWz. Gi s OCCPU l mt class dn xut ca class CPU, by gi thay v truyn vo instance ca class CPU, chng ta c th truyn vo instance ca class OCCPU. Factory c th c dependencies, lc chng ta s dng key deps: Khi c nhiu providers c cng gi tr ca key provide v khng s dng config multi: true th provider no thm vo sau cng s win. Injector c th bit c cch to mt object, chng ta cn cung cp cc providers, chnh l u vo ca method resolveAndCreate. All rights reserved. cp Module, bn khai bo cc provider vo mng providers trong config ca @NgModule decorator. providers: Dng khai bo cc service dng trong ton b cc module ca con (d c lazy loading module hay khng vn available). Vn pht sinh by gi, nu chng ta mun thay instance bng mt instance ca mt class CPU khc, lc ny chng ta bt buc phi vit li class Computer, ngay k c vic test chng trnh cng kh khn v chng ta kh thay i instance cho vic mock d liu test.
c bit i vi cc thit b di ng hay nhng kt ni bng thng thp. trn chng ta lm r c khc bit v scope ca component v service trong module ri. Working on improving health and education, reducing inequality, and spurring economic growth? Cu tr li l c. Trong cc v d trc, chng ta s dng provider vi cu trc ca mt object vi cc key provide v useClass nh sau. You get paid; we donate to tech nonprofits. Angular cung cp mt cch extend PreloadingStrategy xc nh mt ty chnh chin lc Preload ch ra iu kin cho vic preload cc lazy load module. i vi component, s khng c thay i, chng ta vn import module nh trn (tc l import commonModule v cc module cung cp components). T Angular 4 tr i chng ta s dng InjectionToken thay v OpaqueToken (c th b b i trong Angular phin bn > 4). Khi to instance ca class CPU mt context (container) bn ngoi, v truyn vo (inject) cho class Computer, trong trng hp ca JavaScript, TypeScript l truyn qua constructor ca class Computer. Developed by XuanThuLab, NG K KNH, XEM CC VIDEO TRN XUANTHULAB, Truyn d liu quan li gia cc Component trong Angular, S dng Component v cu trc Template trong Angular, Tng quan v ngn ng lp trnh TypeScript, Phi khai bo tt c cc thnh phn m n cn. Then finally, in any feature module we can simply import the shared module without the forRoot and well have access to the shared pipes and directives without providing the service again: Thats it! y chnh l lc chng ta cn n Forward References. Sau y l mt mu thit k cc mudule mu mi ngi c th tham kho. Bn c th ch cn khai bo ng k providers cho accountService bt k feature module no (hoc c th khai bo vo appModule) u c th s dng service bt k module no. If you have any suggestions for improvements, please let us know by clicking the report an issue button at the bottom of the tutorial. tng v vic dng service rt n gin.Nu bn c cc phn code x l business logic v d gi API nhn gi d liu hoc c cc phn code cn s dng li, chng ta s tch cc phn ra khi Component v gi chng l services. Khi c token, DI system s c key tip theo, trong trng hp trn l useClass, vi key trn n s to instance ca class tng ng. Cc loi module cn li gi l module chc nng, c c im sau: Ta dng Module chc nng to ra cc view, V d, trong ng dng v d trc, g lnh sau t ng to khung Module chc nng (t tn module l ModuleChucnang). Cch gii quyt lc ny, chng ta s s dng Forward References nh sau: Trng hp ny bn thng gp phi khi to custom validator directive cho form. Chng ta c th s dng kt hp c hai khi mt class ph thuc vo c kiu d liu primitive v kiu t nh ngha. Chng ta s c 2 cch khi to nh sau: i vi cch 1, chng ta hard-coded khi khi to nh sau: Gi s lc ny chng ta chy chng trnh vi on code nh sau: on code trn khng c g c bit, chng ta khi to instance ca class CPU bn trong contructor ca class Computer. C nhiu token c th cng s dng mt token c. Chng ta c th s phi ti nhng modules m ngi dng c th rt t khi chuyn hng n. By gi mi th li hot ng tht hon ho nh chng ta mong i. Khi ng dng c load, tt c cc components ca cc lazy module u cha c load, m chng ch thc s c load khi m ngi dng s dng n chng. Bt k module no cung cp component, directive, pipe. Click below to sign up and get $100 of credit to try our products over 60 days! c tn l @NgModule khai bo, Module l mt lp cha cc thnh phn thc hin cc chc nng no . Trong trng hp trn, @Inject/@Injectable s nh du cho DI bit tham s u tin ca hm to ca class Computer cn mt instance ca class CPU nu c nhiu tham s hn, n s cho ng th t cc tham s ca hm to DI bit cch inject instances vo. Vy c cc no khi chia cc FeatureModule ri th chng ta cng chia route i km cc FeatureModule khng? Chng ta s to mt provider extend t PreloadingStrategy preload cc modules m c preload: true c xc nh trong cu hnh route. Vi Angular s dng n decorator Sometimes youll want to create a shared module in an Angular app that defines services, pipes and directives that feature modules and lazy-loaded modules can use. Chng ta khng cc Component ph thuc cht ch vo cc services, m thay vo s inject thng qua DI system. trong phn bootstrap phi khai bo cc component khi chy. Bng cch , cc Component c th ph thuc vo Interface Abstraction thay v ph thuc vo class c th, gip d dng kim th, bo tr, nng cp. Nu mun s dng property cpu trong class Computer, chng ta phi khi to u, v nu khng khi to chng ta khng th s dng cc method ca property . Trong trng hp bn mun mt token c th c nhiu value, lc ny bn c th s dng multiple nh sau: Khi kt qu nhn c l mt mng cc gi tr. Token c th l string hoc mt kiu d liu. AppModule v n l 1 phn ca BrowserModule. Cc bn c th xem console ch c 1 ln duy nht log ra counter l 1.Nu chng ta t providers Component, mi ln component c to ra s sinh ra mt instance khc. How To Upgrade from AngularJS to Angular with ngUpgrade, DigitalOcean Kubernetes: new control plane is faster and free, enable HA for 99.95% uptime SLA. Tuy nhin, preload tt c cc lazy load module khng phi lc no cng l s la chn ng n. A neat little trick to make it easier to work with shared modules and lazy-loaded feature modules. This work is licensed under a Creative Commons Attribution-NonCommercial- ShareAlike 4.0 International License. Module c import khi no bn mun cng c (tc l nhiu ln). Quay tr li vn khi chng ta cn thay i mt class khc m vn s dng token trn, chng ta ch cn bo DI class chng ta cn m khng phi sa token class cn ph thuc. declarations: Dng khai bo nhng thnh phn chng ta s dng trn template (thng ch yu l cc component, directive v pipe). Cc bn c th on c mu thit k trn chnh l Dependency Injection (DI), chi tit hn l constructor injection. V d: trong, bootstrap: nh ngha component gc ca module. Khi khi to mt d n hy xem xt k, v nn to ra mt rule thng nht trong qu trnh pht trin khi mi ngi to mt module hay thm nhng component s khng lm ph v cc quy tc mi ngi ang lm. Make sure that all the parameters are decorated with Inject or have valid type annotations and that CPU is decorated with Injectable. N sinh ra file /src/app/module-chucnang/module-chucnang.module.ts c ni dung: Vy l to ra c module chc nng c tn ModuleChucnangModule, lu file vi cu trc th mc nh trn. This post hasn't been updated for 2 years. Angular gip chng ta d dng s dng DI trong ng dng, gi s vi on code pha trn, chng ta c th bin i s dng Angular DI nh sau: i vi vic s dng TypeScript, chng ta c th b qua property ca class v km theo keyword public/private vo tham s ca constructor, TypeScript s compile ra ng nhng g chng ta cn nh sau: Nu ph thuc vo mt class khc, chng ta c th b qua @Inject nh sau: Lu rng, trong Angular 4, tt c cc class c ph thuc n cc thnh phn khc nh class Computer trn s phi decorate bng @Injectable() decorator. NgModule l cu trc c bn u tin chng ta s phi i mt khi vit d n bng Angular. iu ny c th dn n s chm tr khi m ngi dng phi ch i cho module c load => lm cho tri nghim ngi dng xu i. Ngoi ra, DI trong Angular cn mt s kin thc v Controlling Visibility vi cc decorator @SkipSelf, @Host hay @Self cc bn c th vo trang document chnh thc tm hiu thm. Kt qu cui cng ca API_ENDPOINT s l http://tiepphan.com/thu-nghiem-voi-angular-dependency-injection-trong-angular/. @Inject/@Injectables thm cc metadata vo class Computer, m sau ny s c s dng bi DI system. V d: Hoc trong trng hp bn mun s dng mt token khc cho tham s thay v kiu d liu ca n chng hn. M file template app.component.html thm vo cui tag
Nhng Module c tn AppModule l module gc, n c dng khi chy ng dng, cn li th l loi Module chc nng. Module gc c khi chy bng on m (/src/main.ts). N cng l th phc tp v kh ri rm v scope nh hng khc nhau khi khai bo module theo cc cch khc nhau. nh du mt dependency l optional c cng c, khng c cng c chng ta s dng@Optionaldecorator. Khi s dng cc components khc nhau nhng chng ta ch c mt instance duy nht. Tm ra s cn bng c v hiu nng v tri nghim ngi dng l cha kha cho vic pht trin. Module gc c tn l AppModule, th n phi khai bo c import BrowserModule, y l blog c nhn, ti ghi chp v chia s nhng g ti hc c y v kin thc lp trnh PHP, Java, JavaScript, Android, C# v cc kin thc cng ngh khc Khi bn mun tr v mt value da vo mt iu kin u vo, hoc bn mun mi ln gi n instance ca token s cho mt instance khc nhau th bn s dng factory function nh sau. Nh vy l chng ta Lazy Load thnh cng th ci thin c ng k tc load ln u ca ng dng. MatXModule cng nhng cc module UI theme. Hoc bn cn to mt instance ca mt class c tham s ca hm to l kiu primitive. Lc ny bn cn n @Inject decorator, gn cho tham s mt token no . Luckily for us however, theres an easy fix for that specific use-case by defining a static forRoot method in the shared module that returns a ModuleWithProviders object. Mc d i ng pht trin ca Angular hon thin ton b bng FAQ v module, nhng chng cn kh ri rm nhng ngi mi bt u c th tip cn, c bit khi kt hp module cng vi routing s cng gy ra nhng kh khn ln hn na. Heres a sample implementation. Vy vi cch implement ny, c g khc vi cch import tt c vo AppModule? BrowserAnimationsModule hay NoopAnimationsModule. Gi s to ra mt component c tn l Vidu01Component s dng cho module ny g lnh sau: N sinh ra cc file trong th mc /src/module-chucnang/vidu01-component v trong c nh ngha
Module l cch chia nh cc thnh phn ng dng (ging package trong Java). http://tiepphan.com/thu-nghiem-voi-angular-dependency-injection-trong-angular/, https://drive.google.com/file/d/0B-ux0B5az7XuNG9FaW5YVUJ6Nm8/view?usp=sharing. The one little hiccup is that services, which are normally supposed to act as singletons, could end up being provided multiple times, especially for lazy-loaded modules. While we believe that this content benefits our community, we have not yet thoroughly reviewed it. Hy quan st v d sau: Chng ta mong mun nhn c mt mng chy, nhng khi chy chng trnh chng ta gp phi li chng hn nh: Error: Invalid provider for COMP. Chng ta vn c th thy c nhng service c provide AppModule. Ti sao c 2 cch m t cho cng mt vn . Nu khng, chng ta c th s gp phi li khng tm thy component v chng ta cha import module vo. By gi t ra tnh hung, bn mun to mt provider m class bn nh ngha sau khi to provider th s th no. useClass cannot be undefined. Tuy nhin module Setings s c ngi dng s dng nhng vi tun sut rt thp. Bnh thng vi nhng Angular App t chc nng, t module v route th chng ta c th import tt cc Module vo AppModule v thm route vo ngay AppRoutingModule. Now, in our app module, we can import the shared module and call forRoot on it to also provide our service: Youll probably notice that youve seen this in action already when importing the RouterModule and calling forRoot on it in your app module. Nu Component/Directive Y cng dng n Dependency ging X, th instance ca dependency s dng trong X v Y l khc nhau. Tuy nhin vi nhng d n ln vic load tt c cc module cng lc khi ti trang s c th gy chm tr lm gim tri nghim ngi dng, hn na vic vit tt c cc route vo AppRoutingModule cng s gy kh trong qu trnh pht trin file qu di cng gy c ch trong qu trnh pht trin. Chng ta s dng ReflectiveInjector ly c object ca class Computer chnh l Injector thng qua method resolveAndCreate. iu ny tht tuyt phi khng no, chng ta khng cn vit li class Computer, khng cn chy li tt c cc test case lin quan, c mng s gim i rt nhiu. S ra sao nu bn s dng @Injectable trong trng hp hm to c tham s l mt kiu d liu primitive. Scope ca nhng service (c khai bo trong thuc tnh providers) c th s dng trong ton b d n. n y cc bn thy vic s dng service l PostService. Copyright 2017 to present - tiepphan.com All rights reserved. Join our DigitalOcean community of over a million developers for free! Khi trong class A c s tn ti ca class B, dng class B lm mt cng vic no , ta ni rng class A ang ph thuc vo class B. V d, chng ta c class Computer v class CPU nh sau: Nh v d trn, class Computer ang ph thuc vo class CPU. trnh nhp nhng token, chng ta s dng OpaqueToken (Angular 2) hoc InjectionToken (ch c trong Angular 4+) to cc unique token. V d chng ta s dng token CPU nhng dng class OCCPU nh sau chng hn: Sau khi Injector khi to cc objects v inject cc dependencies cn thit, chng ta c th ly ra c object m chng ta mong mun vi phng thc get: n thi im ny, mi khi bn gi injector.get cho provider dng useClass s lun nhn c cng mt object singleton. v d trn, chng ta truyn vo mt mng cc class. Dependency: l mt object ca mt kiu d liu cn phi khi to. Do vy m vic preload module Email s em li hiu qu cao, trong khi vi module Setings th thp. Thc cht l cch vit ngn gn ca mt mng object c dng nh sau: Chng ta c object vi key provide, y l token DI system map vi token m @Inject/@Injectable m t. We'd like to help. Ngay k c khi bn vit theo TypeScript nh sau: Lc bn khng bit cch lm th no bo cho DI bit kiu ca token l g v DI s khng th inject dependencies cn thit cho bn c, bn c th gp li sau y. CommonModule Cha tt c cc thnh phn ca Angular (structure directive nh *ngIf, *ngFor..): Module ny ta s import nhiu module con nhng khng import vo module. Bi vit ny s gii thiu v Dependency Injection trong Angular mt trong nhng tnh nng quan trng ca Angular cho n thi im hin ti ch c Angular l framework duy nht pha client cung cp DI. => Cu tr li l c, v chnh l preload, Vy cch d dng ra sao? 2022 DigitalOcean, LLC. Ngoi cch trn chng ta c th s dng mt s cch di y: Nu bn s dng token nh sau, value s c truyn vo thay v to instance ca class. Provider: ging nh mt cng thc Injector c th bit lm th no to mt instance ca mt ph thuc. Nhng module no ch cung cp services: L do chng ta s ni khi qua vn v lazyloading. cp Component/Directive, bn khai bo cc provider vo mng providers trong config ca @Component/@Directive decorator. Instead, we define a static forRoot method in the modules class that returns an object that implements Angulars ModuleWithProviders interface. Get help and share knowledge in our Questions & Answers section, find tutorials and tools that will help you grow as a developer and scale your project or business, and subscribe to topics of interest. Hy cng xem v d ca mnh nh: V d mt app v giao dc c 3 role l admin, teacher v student. Email module Chng ta c th ci thin code trn bng cch s dng cch 2, vi vic inject cc ph thuc. Vi mi route ny mnh s chia n thnh mi feature module, trong mi feature module mnh s c mt file route nm trong module , nh ngha cc route lin quan n cc mn hnh trong role , Hy ch n : RouterModule.forChild(routes) y nh, Nh cch implement trn, ta c th hiu rng vi role admin khi ta tra cp cc trang trong module th path lc no cng bt u bng "admin" v d 'admin/users', 'admin/users/1', tng t vi student v teacher, Vi 3 FeatureModule kia chng khng cn phi thm trc tip vo AppModule, vi cch implement kia chng ta thc vic c LazyLoad Module, tc ta khi no ngi dng vo nhng ng dn ca tng feature th module mi c load, tc l Khi vo ng dn ban u v d: localhost:4200, th nhng Feature Module kia u cha c load, khi vo ng dn chng hn localhost:4200/admin/users th module admin mi c load. V d, c 1 accountService, v 2 module userModule v orderModule c inject vo AppModule. C php to ra mt module, v d module ModuleName (class) nh sau: Trong v d mu phn To ng dng Angular u tin Lc ny mi instance ca Component/Directive X s s dng mt instance ca token (khng phi dng multiple) tng ng.
Tm hiu v module, cc loi module, khai bo v s dng module trong Angular. iu c ngha l i vi feature module (khng lazy load) cc service ch cn c khai bo bt k module con no, khi import vo module chnh s public single instance trn ton b module con v module chnh.