Bagaimana cara menyimpan hasil dalam variabel dengan benar? XLSX Angular

Aug 19 2020

Saya sedang membaca file excel dari input dengan Angular dan mengubah data file itu menjadi array objek. Komponen saya seperti ini:

import * as XLSX from 'xlsx';
import { Injectable } from '@angular/core';

@Injectable({ providedIn:'root' })
export class ExcelService {

    arrayBuffer: any;

    constructor() {}

    xlsxToJSON(event) {
        let arreglo;   
        let fileReader = new FileReader();    
        fileReader.readAsArrayBuffer(event);
        fileReader.onload = async(e)  => {    
            this.arrayBuffer = fileReader.result;    
            let data = new Uint8Array(this.arrayBuffer);    
            let arr = new Array();    
            for(let i = 0; i != data.length; ++i) arr[i] = String.fromCharCode(data[i]);    
            let bstr = arr.join("");    
            let workbook = XLSX.read(bstr, {type:"binary"});    
            let first_sheet_name = workbook.SheetNames[0];    
            let worksheet = workbook.Sheets[first_sheet_name];    
            // console.log(XLSX.utils.sheet_to_json(worksheet,{raw:true}));
            // arraylist es el JSON después de tratar la data del excel
            let arraylist = XLSX.utils.sheet_to_json(worksheet,{raw:true});
            arreglo = arraylist;
            console.log('El arraylist'+ arraylist);
            console.log(typeof arraylist);
            console.log('Excel Service: '+arraylist);
            console.log(arreglo);
            return arraylist;
        }
        console.log('ULTIMO LOG'+arreglo);
    } 
}

Saya mendapat layanan untuk menggunakannya dari komponen lain:

import { Component, OnInit } from '@angular/core';
import { Router } from '@angular/router';
import { ExcelService } from '../services/excel.service';

@Component({
  selector: 'app-Zorro',
  templateUrl: './Zorro.component.html',
  styleUrls: ['./Zorro.component.css']
})
export class ZorroComponent implements OnInit {

  file: File;

  ngOnInit() {}
  
  async importExcel (event) {
    this.file = (event.target as HTMLInputElement).files[0]; 
    const result = await this.excelService.xlsxToJSON(this.file);
    console.log('Result: '+result);
  }
}

Dan kemudian komponen HTML saya:

<div class="container">
  <div class="row">
    <div class="col-md-12 form-group">        
      <input 
        type="file" 
        class="form-control" 
        (change)="importExcel($event)" 
        placeholder="Upload file" 
        accept=".csv,application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, application/vnd.ms-excel">        
    </div>
  </div>
</div>

Saya menggunakan banyak "console.log ()" untuk melihat apa yang saya dapatkan, sampai sekarang saya dapat mengubah file itu menjadi objek JS, tetapi ketika saya perlu menggunakan hasilnya, variabel tempat saya menyimpan hasilnya tidak terdefinisi, saya tebak ini terjadi karena prosesnya asynchronous, saya sudah mencoba dengan async / await, tetapi tidak berhasil. Tujuannya adalah mengambil larik objek ini dan mengirimkannya ke backend lalu ke basis data.

Jawaban

Noname Aug 19 2020 at 11:41
import { Component, OnInit } from '@angular/core';
import { DataService } from '../../services/data.service';
import * as jspdf from 'jspdf';
import html2canvas from 'html2canvas';
// import * as XLSX from 'xlsx';

import * as ExcelJS from 'exceljs';
import * as FileSaver from 'file-saver';

import { ViewChild, ElementRef } from '@angular/core';

@Component({
  selector: 'app-items-report',
  templateUrl: './items-report.component.html',
  styleUrls: ['./items-report.component.css']
})
export class ItemsReportComponent implements OnInit {

  purchases: any;
  constructor(private dataService: DataService) {
    this.GetPurchases();
  }

  ngOnInit(): void {
  }

  async GetPurchases() {
    const response = await this.dataService.GetPurchases();
    const dataService = await response.json();
    this.purchases = dataService;
  }


  downloadExcel() {

    // using instead of Date.now()
    const date = new Date().toISOString().slice(0, 10).split('-').reverse().join('/');
    console.log(date);

    // get help from here for excel file export using excelJS with alignment
    // in your tsconfig.app.json u must use "types": ["node"] if u use exceljs
    // https://stackoverflow.com/questions/62127452/angular-cant-export-excel-using-exceljs-error-ts2307-cannot-find-module-s/62128182?noredirect=1#comment109909862_62128182

    const workbook = new ExcelJS.Workbook();
    const worksheet = workbook.addWorksheet('My Sheet');

    worksheet.columns = [
      { header: 'Id', key: 'id', width: 10},
      { header: 'Name', key: 'name', width: 32 },
      { header: 'Quantity', key: 'quantity', width: 15 },
      { header: 'Rate', key: 'rate', width: 15 },
      { header: 'Date', key: 'date', width: 15 },
      { header: 'Total', key: 'total', width: 15 }
    ];

    // get help from here for excel cell alignment
    // https://openbase.io/js/exceljs#alignment


    for (const purchase of this.purchases) {
      worksheet.addRow({
        id: purchase.item_id ,
        date: purchase.item_purchase_date.toString().slice(0, 10).split('-').reverse().join('/'),
        name: purchase.item_name,
        quantity: purchase.item_quantity,
        rate: purchase.item_rate,
        total: purchase.item_rate * purchase.item_quantity
       })
      .alignment = { horizontal: 'left' };
    }

    worksheet.getRow(1).font = { bold: true };

    // get help from here
    // https://stackoverflow.com/questions/62149358/exceljs-iterate-each-cell-of-each-row-and-column/62149808#62149808
    worksheet.columns.forEach(column => {
      // for each non empty cell
      column.eachCell((cell, rowNumber) => {
        cell.border = {
          top: { style: 'thick' },
          left: { style: 'thick' },
          bottom: { style: 'thick' },
          right: { style: 'thick' }
        };
      });
    });





    // save under export.xlsx, dont use writeFile see the above stackoverflow question
    // await workbook.xlsx.writeFile('export.xlsx');
    // await maybe optional here
    workbook.xlsx.writeBuffer()
      .then(buffer => FileSaver.saveAs(new Blob([buffer]), `${date}_feedback.xlsx`))
      .catch(err => console.log('Error writing excel export', err));

}

gunakan exceljs. Anda dapat melihat saya menggunakan data async saya untuk membuat file excel