【Salesforce】LWCでCSVファイルをインポートする

<template>
	<lightning-card title="My CSV Import">
		<div class="slds-var-m-around_medium">
			<lightning-input
				type="file"
				label="CSVファイル（取引先責任者）"
				accept="text/csv"
				onchange={handleChangeFile}>
			</lightning-input>
			<div class="slds-m-vertical_small">
				<p>ファイル名：{importFileName}</p>
				<p>件数：{importFileRowCount}</p>
			</div>
			<lightning-button variant="brand" label="インポート" onclick={handleImport}></lightning-button>
		</div>
	</lightning-card>
</template>

import { LightningElement, api } from 'lwc';
import { ShowToastEvent } from 'lightning/platformShowToastEvent';
import importContacts from '@salesforce/apex/MyCSVImportController.importContacts';

export default class MyCSVImport extends LightningElement {
	@api recordId;
	importFileData;
	importFileName;
	importFileRows;
	importFileRowCount;

	// ファイル選択時の処理
	handleChangeFile(event) {
		const fileReader = new FileReader();
		const selectedFile = event.detail.files[0];
		this.importFileName = selectedFile.name;

		fileReader.onloadend = () => {
			this.importFileData = fileReader.result;
			this.importFileRows = this.importFileData.split(/\r\n|\n/);
			this.importFileRowCount = this.importFileRows.length - 1;
		}
		
		fileReader.readAsText(selectedFile, 'Shift_JIS');
	}

	// インポートボタン押下時の処理
	async handleImport() {
		this.checkFileSelected();

		const rows = this.importFileRows;
		const contacts = [];
		for(let i = 1; i < rows.length; i++) {
			const cols = rows[i].split(',');
			contacts.push({
				lastName: cols[0],
				firstName: cols[1],
				email: cols[2],
			});
		}

		try {
			await importContacts({ accId: this.recordId, contacts: JSON.stringify(contacts) });
			const showSuccess = new ShowToastEvent({
				title: 'Success',
				message: 'インポート成功。',
				variant: 'success',
			});

			this.dispatchEvent(showSuccess);
		}
		catch(e) {
			const showError = new ShowToastEvent({
				title: 'Error',
				message: e.body.message,
				variant: 'error',
			});
			this.dispatchEvent(showError);
		}
	}

	// ファイル選択済みチェック処理
	checkFileSelected() {
		if(!this.importFileData) {
			const showError = new ShowToastEvent({
				title: 'Error',
				message: 'ファイルが選択されていません。',
				variant: 'error',
			});
			this.dispatchEvent(showError);
			return;
		}
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata">
    <apiVersion>58.0</apiVersion>
    <isExposed>true</isExposed>
    <targets>
        <target>lightning__RecordPage</target>
    </targets>
</LightningComponentBundle>

public with sharing class MyCSVImportController {
    @AuraEnabled
    public static void importContacts(String accId, String contacts){

        List<Object> targetContactList = (List<Object>)JSON.deserializeUntyped(contacts);
        List<Contact> importContactList = new List<Contact>();

        for(Object obj : targetContactList) {
            Map<String, Object> fieldNameToValue = (Map<String, Object>)obj;
            Contact c = new Contact();
            c.AccountId = accId;
            c.LastName = (String)fieldNameToValue.get('lastName');
            c.FirstName = (String)fieldNameToValue.get('firstName');
            c.email = (String)fieldNameToValue.get('email');
            importContactList.add(c);
        }

        try {
            insert importContactList;
        }
        catch(DmlException e) {
            throw e;
        }
    }
}