[英]How can we get data from mysql database in angular 7 application by using node.js and display it on angular component html page
我已经尝试了所有事情,但是我无法理解如何实现自己的目标。 现在我的主要目标是我想从mysql数据库中获取数据,然后在有角度的组件(page-one.component.ts文件)中访问此信息。 现在,我可以连接到数据库,并且可以从server.js文件中的数据库获取数据。 但我不明白如何获取角度分量信息。 到目前为止,我尝试过的方法是将我的server.js文件包含在angular.json文件中,然后在我的page-one.component中包含函数“ get_data”(get_data函数从server.js文件中的数据库获取数据)。 ts文件,然后在page-one.component.ts文件中调用该函数。 该函数被调用,但是问题是我在server.js文件中遇到了“无法读取未定义的属性'createConnection'”错误。 此错误使我无法从数据库中获取信息。 但是当我在server.js文件中调用此get_data函数时,我得到了数据库信息,并且可以在控制台中打印该信息。 谁能给我解决方案。 我认为错误是由于变量的上下文。 但请指导我。
我的server.js文件代码。
const express = require('express');
const path = require('path');
const http = require('http');
const socketIO = require('socket.io');
const app = express();
const server = http.createServer(app);
const port = process.env.PORT || 3000;
app.use(express.static(path.join(__dirname, 'dist')));
app.get('*', (req, res) => {
res.sendFile(path.join(__dirname, 'dist/index.html'));
});
var mysql = require('mysql');
var dbconfig = {
host: "localhost",
user: "root",
password: "",
database: "mydb"
}
var con = mysql.createConnection(dbconfig);
con.connect(function (err) {
if (err) throw err;
console.log("Connected!");
});
get_data();
function get_data(){
console.log("function called");
var con = this.mysql.createConnection(dbconfig); ===> GOT ERROR HERE
con.query("SELECT * FROM teacher", function (err, result, fields) {
if (err) throw err;
console.log(result);
});
}
server.listen(port, () => {
console.log(`server running on port ${port} `);
})
我的page-one.component.ts文件代码。
import { Component, OnInit } from '@angular/core';
import { Http } from '@angular/http';
declare function get_data(): any;
@Component({
selector: 'app-page-one',
templateUrl: './page-one.component.html',
styleUrls: ['./page-one.component.css']
})
export class PageOneComponent implements OnInit {
constructor(private http: Http) { }
ngOnInit() {
get_data();
}
}
我的angular.json文件代码。
{
"$schema": "./node_modules/@angular/cli/lib/config/schema.json",
"version": 1,
"newProjectRoot": "projects",
"projects": {
"myapp": {
"root": "",
"sourceRoot": "src",
"projectType": "application",
"prefix": "app",
"schematics": {},
"architect": {
"build": {
"builder": "@angular-devkit/build-angular:browser",
"options": {
"outputPath": "dist/myapp",
"index": "src/index.html",
"main": "src/main.ts",
"polyfills": "src/polyfills.ts",
"tsConfig": "src/tsconfig.app.json",
"assets": [
"src/favicon.ico",
"src/assets"
],
"styles": [
"src/styles.css"
],
"scripts":
[
"server.js" ===> INCULDED THE SERVER.JS FILe HERE
]
},
"configurations": {
"production": {
"fileReplacements": [
{
"replace": "src/environments/environment.ts",
"with": "src/environments/environment.prod.ts"
}
],
"optimization": true,
"outputHashing": "all",
"sourceMap": false,
"extractCss": true,
"namedChunks": false,
"aot": true,
"extractLicenses": true,
"vendorChunk": false,
"buildOptimizer": true
}
}
},
"serve": {
"builder": "@angular-devkit/build-angular:dev-server",
"options": {
"browserTarget": "myapp:build"
},
"configurations": {
"production": {
"browserTarget": "myapp:build:production"
}
}
},
"extract-i18n": {
"builder": "@angular-devkit/build-angular:extract-i18n",
"options": {
"browserTarget": "myapp:build"
}
},
"test": {
"builder": "@angular-devkit/build-angular:karma",
"options": {
"main": "src/test.ts",
"polyfills": "src/polyfills.ts",
"tsConfig": "src/tsconfig.spec.json",
"karmaConfig": "src/karma.conf.js",
"styles": [
"src/styles.css"
],
"scripts": [],
"assets": [
"src/favicon.ico",
"src/assets"
]
}
},
"lint": {
"builder": "@angular-devkit/build-angular:tslint",
"options": {
"tsConfig": [
"src/tsconfig.app.json",
"src/tsconfig.spec.json"
],
"exclude": [
"**/node_modules/**"
]
}
}
}
},
"myapp-e2e": {
"root": "e2e/",
"projectType": "application",
"architect": {
"e2e": {
"builder": "@angular-devkit/build-angular:protractor",
"options": {
"protractorConfig": "e2e/protractor.conf.js",
"devServerTarget": "myapp:serve"
},
"configurations": {
"production": {
"devServerTarget": "myapp:serve:production"
}
}
},
"lint": {
"builder": "@angular-devkit/build-angular:tslint",
"options": {
"tsConfig": "e2e/tsconfig.e2e.json",
"exclude": [
"**/node_modules/**"
]
}
}
}
}
},
"defaultProject": "myapp"
}
“无法读取未定义的属性'createConnection'”
const mysql = require('mysql2'); const connection = mysql.createPool({ host: 'localhost', user: '', password: '', database: '', connectionLimit: 10, queueLimit: 0 }); connection.promise((err) => { if (err) throw err; console.log('connected!'); }); module.exports = connection.promise();
app.get("/youroute", (req, res, next) => { "use strict"; const getProduct = "SELECT * FROM yourtable"; database.query(getProduct, (err, rows, fields) => { if (err) { res.status(500).send({ error: 'Something failed!' }) }; res.status(200).json({ message: "", product: rows, }); }); });
Service for Angular export interface You { id: number, title: string, content: string } Get Method on Model Angular getData() { this.http.get<{message:string,name:Name[]}>("URL") .subscribe(result =>{ console.log(result); }); and in HTML make For Loop with NGFOR for display your data
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