Empty cell validation while upload file in angular

To perform empty cell validation while uploading a file in an Angular application, you can use the xlsx library to read the data from the uploaded Excel file and then validate the cells for emptiness. Here's a step-by-step guide on how to achieve this:

1. Install the Required Libraries:

   • First, install the required libraries: xlsx and file-saver.

   bashCopy code
   npm install xlsx file-saver --save
   

2. Create a File Upload Component:

   • Create a component that allows users to upload an Excel file. Use the <input type="file"> element to facilitate the file selection.

   htmlCopy code
   <!-- file-upload.component.html -->
   <input type="file" (change)="onFileChange($event)">
   

3. Read and Validate the Uploaded File:

   • In the component's TypeScript file, read and validate the uploaded file.

   typescriptCopy code
   // file-upload.component.ts
   import { Component } from '@angular/core';
   import * as XLSX from 'xlsx';
   import { saveAs } from 'file-saver';
   
   @Component({
     selector: 'app-file-upload',
     templateUrl: './file-upload.component.html',
     styleUrls: ['./file-upload.component.css']
   })
   export class FileUploadComponent {
     onFileChange(event: any): void {
       const file = event.target.files[0];
       const fileReader = new FileReader();
   
       fileReader.onload = (e: any) => {
         const arrayBuffer = e.target.result;
         const workbook = XLSX.read(arrayBuffer, { type: 'array' });
         const firstSheetName = workbook.SheetNames[0];
         const worksheet = workbook.Sheets[firstSheetName];
   
         const data = XLSX.utils.sheet_to_json(worksheet, { header: 1 });
         const emptyCells = this.findEmptyCells(data);
   
         if (emptyCells.length === 0) {
           // All cells are valid, proceed with further processing
         } else {
           // Handle empty cell validation errors
           console.log('Empty cell validation failed');
         }
       };
   
       fileReader.readAsArrayBuffer(file);
     }
   
     findEmptyCells(data: any[][]): string[] {
       const emptyCells: string[] = [];
   
       data.forEach((row, rowIndex) => {
         row.forEach((cell, colIndex) => {
           if (cell === null || cell === '') {
             emptyCells.push(`Cell at row ${rowIndex + 1}, column ${colIndex + 1}`);
           }
         });
       });
   
       return emptyCells;
     }
   }
   

4. Handle the Validations and Further Processing:

   • In the onFileChange method, you can handle the validation results. If all cells are valid, you can proceed with further processing, such as sending the data to a backend API or displaying it on the front-end.

5. Styling and Error Handling:

   • Add appropriate styling and error handling to your component's template and logic to provide a user-friendly experience.

By following these steps, you can implement empty cell validation while uploading an Excel file in your Angular application. This approach uses the xlsx library to read and parse the Excel file, and then custom logic is applied to validate the cells for emptiness.