So erstellen Sie eine API-Daten-Paginierung mit Node Express

Node Express ist ein JavaScript-Framework, mit dem eine Vielzahl von Webanwendungen entwickelt werden kann. Es kann verwendet werden, um Web-APIs zu entwickeln, die von verschiedenen Client-Apps (Web-App oder mobile Apps) verwendet werden können. Die Daten-Paginierung muss für API-Antworten implementiert werden, die lange Datenlisten beinhalten. Dieser Artikel zeigt Ihnen Schritt für Schritt, wie die Daten-Paginierung in Node Express-APIs implementiert wird.

In diesem Beispiel geht es um eine Nachrichten-App.

Schritt 1: Erstellen Sie einen leeren Ordner namens newsapp .

$ mkdir newsapp
cd newsapp
$ npm init

$ npm install express --save

$ npm install mongoose --save

const mongoose = require('mongoose')

const mongoose = require('mongoose')
const ArticleSchema = new mongoose.Schema({
   title: { 
    type: String,
    required: true
   },
   content: {
    type: String,
    required: true
 }
})

module.exports = mongoose.model('Article', ArticleSchema)

const mongoose = require('mongoose')
const ArticleSchema = new mongoose.Schema({
   title: { 
    type: String,
    required: true
   },
   content: {
    type: String,
    required: true
 }
})
module.exports = mongoose.model('Article', ArticleSchema)

const express = require('express')
const newsapp = express()
const mongoosedb = require('mongoose')

const article = require('./articles')

mongoose.connect('mongodb://localhost:27017/test', {useNewUrlParser: true, useUnifiedTopology: true});

const db = mongoose.connection
db.once('open', async () => {
  if (await article.countDocuments().exec() > 0) return
Promise.all([
article.create({ title: 'article 1', 
                content: "News content for article 1" }),
article.create({ title: 'article 2', 
                content: "News content for article 2" }),
article.create({ title: 'article 3', 
                content: "News content for article 3" }),
article.create({ title: 'article 4', 
                content: "News content for article 4" }),
article.create({ title: 'article 5', 
                content: "News content for article 5" }),
article.create({ title: 'article 6', 
                content: "News content for article 6" }),
article.create({ title: 'article 7', 
                content: "News content for article 7" }),
article.create({ title: 'article 8', 
                content: "News content for article 8" }),
article.create({ title: 'article 9', 
                content: "News content for article 9" }),
article.create({ title: 'article 10', 
                 content: "News content for article 10" }),
article.create({ title: 'article 11', 
                content: "News content for article 11" }),
article.create({ title: 'article 12', 
                content: "News content for article 12" }),
article.create({ title: 'article 13', 
                content: "News content for article 13" })
]).then(() => console.log('Added Articles'))
})

function paginatedNewsArticles(model) {
   return async (request, response, next) => {
     const querypage = parseInt(request.query.page)
     const querylimit = parseInt(request.query.limit)
}}

const firstIndex = (page - 1) * limit
const lastIndex = page * limit
if (firstIndex > 0) {
      paginatedArticlesList.previous = {
      previouspage: page - 1,
      limit: limit
    }
  }
if (lastIndex < await model.countDocuments().exec()) {
      paginatedArticlesList.next = {
       nextpage: page + 1,
       limit: limit
     }
}

const express = require('express')
const newsapp = express()
const mongoosedb = require('mongoose')
const article = require('./articles')
mongoose.connect('mongodb://localhost/pagination', { useNewUrlParser: true, useUnifiedTopology: true })
const db = mongoose.connection
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', async () => {
  if (await article.countDocuments().exec() > 0) return
Promise.all([
   article.create({ title: 'article 1', 
                content: "News content for article 1" }),
   article.create({ title: 'article 2', 
                content: "News content for article 2" }),
   article.create({ title: 'article 3', 
                content: "News content for article 3" }),
   article.create({ title: 'article 4', 
                content: "News content for article 4" }),
   article.create({ title: 'article 5', 
                content: "News content for article 5" }),
   article.create({ title: 'article 6', 
                content: "News content for article 6" }),
   article.create({ title: 'article 7', 
                content: "News content for article 7" }),
   article.create({ title: 'article 8', 
                content: "News content for article 8" }),
   article.create({ title: 'article 9', 
                content: "News content for article 9" }),
   article.create({ title: 'article 10', 
                 content: "News content for article 10" }),
   article.create({ title: 'article 11', 
                content: "News content for article 11" }),
   article.create({ title: 'article 12', 
                content: "News content for article 12" }),
   article.create({ title: 'article 13', 
                content: "News content for article 13" })
]).then(() => console.log('Added Articles'))
})
newsapp.get('/article', paginatedNewsArticles(article), (request, response) => {
response.json(response.paginatedResults)
})
function paginatedNewsArticles(model) {
  return async (request, response, next) => {
    const querypage = parseInt(request.query.page)
    const querylimit = parseInt(request.query.limit)
    const firstIndex = (page - 1) * limit
    const lastIndex = page * limit
    const paginatedArticlesList = {}
   if (firstIndex > 0) {
       paginatedArticlesList.previous = {
       previouspage: page - 1,
       limit: limit
     }
   }
   if (lastIndex < await model.countDocuments().exec()) {
       paginatedArticlesList.next = {
       nextpage: page + 1,
       limit: limit
     }
}
try {
   paginatedArticlesList.results = await
   model.find().limit(limit).skip(firstIndex).exec()
   response.paginatedArticles = paginatedArticlesList
   next()
} catch (e) {
   response.status(500).json({ message: e.message })
}
}}
newsapp.listen(3000)

Und da haben wir es. Ich hoffe, Sie fanden dies nützlich. Ich melde mich mit weiteren interessanten Artikeln zurück. Vielen Dank fürs Lesen.

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