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Encapsulation method portal:

  • Egg Introduction Basics Egg introduction to project creation
  • Egg Project Directory and controller
  • Egg Basic Egg unit tests
  • Egg Basic HTTP request
  • Egg Basic knowledge Egg Service Service

Introduction to the

HTTP: / / HTTP: / / HTTP: / / HTTP: / / HTTP: / / HTTP: / / HTTP: / / HTTP: / / HTTP: / / A Service is an abstraction layer used to encapsulate business logic in complex business scenarios. So why Service? In practice, controllers generally do not produce their own data, nor do they contain complex logic, so complex processes should be abstracted as business logic layer Services.

Benefits:

  • keepControllerThe logic is more concise.
  • Keep business logic independent and abstractServiceCan be multipleControllerRepeat the call.
  • Separating logic from presentation makes it easier to write test cases.

newService

  • Create a new service under the app file and a new article. Js file under the service

  • In app/service/article. Js, you can see that the naming conventions of service and writing are very similar to Controller. Methods in a Service are also asynchronous methods, so use the async keyword

    'use strict';

const Service = require('egg').Service;

class ArticleService extends Service {
  async getArticle(id) {
    // You should go to the database to query the corresponding article details
    // const article = await this.ctx.query(`select * from articles where id = ? `, id)
    // There is no database connection, so the simulated data is used here
    const article = {
      id: id,
      title: '100 VUE trivia Things Rain Creek Didn't know'.content: 'This is content, this is content, this is content, this is content, this is content.'.author: 'vience'
    }
    returnarticle; }}module.exports = ArticleService;
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  • Write the getArticle() method to getArticle details in app/controller/artile.js, By CTX. Service. Article. GetArticle () call service in getArticle () method. GET from ctx.params using the strict GET mode parameter.

    // Get the article by id
async getArticle() {
  const { ctx } = this;
  const res = await ctx.service.article.getArticle(ctx.params.id);
  ctx.body = res
}
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  • Configure the routing address of the above method in app/router.js

    / / access path: http://127.0.0.1:7001/getArticle/0002
router.get('/getArticle/:id', controller.article.getArticle);
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  • Use the following command to run projects, and then type http://localhost:7001/getArticle/0001 in your browser

    # use npm
npm run dev
open http://localhost:7001/

# use yarn
yarn dev
open http://localhost:7001
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  • The effect

Matters needing attention

  • The Service file must be stored in the app/ Service directory. Multi-level directories can be supported. When accessing the file, the directory name can be cascaded.

    app/service/biz/user.js => ctx.service.biz.user
app/service/sync_user.js => ctx.service.syncUser
app/service/HackerNews.js => ctx.service.hackerNews
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  • A Service file can contain only one class, which is returned via module.exports.

  • A Service needs to be defined as a Class, and its parent must be egg.service.

  • A Service is not a singleton, but a request-level object. The framework delays instantiation when it first accesses ctx.service.xx in each request, so the context of the current request can be obtained in a Service through this.ctx.

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