Salesforce tutorial Lightning Web Component :LWC

2 Ways to connect to apex

call apex using wired attribute

call apex by event click(imperatively)

@wire Components use @wire in their JavaScript class to specify a wire adaptor or an Apex method.

To mark an apex to be callable from lwc

@AuraEnabled(cacheable=true)

public static String makeGetCallout() {

Invoking APEX using wired attribute handon demo and more details

Introduction to Lightning Data services.

How to use template LDS to perform dml ,without apex coding.

Lightning web components have a lifecycle managed by the framework. The framework creates components, inserts them into the DOM, renders them, and removes them from the DOM. It also monitors components for property changes. Generally, components don’t need to call these lifecycle hooks, but it is possible.

More handson hooks example

 What are nested  events

How to handle nested events

When are nested events used

What are custom events

How to handle custom events

When are custom events used

Lightning Data Service is built on top of User Interface API. UI API is a public Salesforce API that Salesforce uses to build Lightning Experience and Salesforce for iOS and Android.

Like its name suggests, UI API is designed to make it easy to build Salesforce UI.

UI API responses also respect CRUD access, field-level security settings, and sharing settings

import { deleteRecord } from 'lightning/uiRecordApi';

import { updateRecord } from 'lightning/uiRecordApi

Create local variables and bind them to input tags

@track contactId;

@track firstName;

@track lastName;

IN JS bind the local to the schema variable

<lightning-input type="text" label="" name="input1" value={relatedContactObj.LastName} onchange={onLastNameChange}></lightning-input>

In the onchange handler assign the values to the local variables

This.firstname =e.target.value

Within lwc build json object with fields api name and values,map the imported schema to local variables

const recordInput = {

ields: {

[Id.fieldApiName]: this.contactId,

[contactFirstName.fieldApiName]: this.firstName,

[contactLastName.fieldApiName]: this.lastName,

}

;

Once this recordinput is created pass it to createrecord or updaterecord

this.contactId = event.target.dataset.recordid;//this requires usage of data tags in lightning-input

<lightning-record-form object-api-name={accountObject}

fields={myFields}onsuccess={handleAccountCreated}> //this part submits the record

</lightning-record-form>

Almost codeless, useage

Import he UI recordpi object and fieldsnames

Import the createrecordmethod from API

Syntax

import ACCOUNT_OBJECT from '@salesforce/schema/Account';

import NAME_FIELD from '@salesforce/schema/Account.Name';

import AccountRevenue__cField from '@salesforce/schema/Account.AccountRevenue__c';

import { createRecord } from 'lightning/uiRecordApi';

accountObject = ACCOUNT_OBJECT;

myFields = [NAME_FIELD, AccountRevenue__cField];

// eslint-disable-next-line no-console

handleAccountCreated(result) {console.log(result);}

Can only overide record detail pages for access to object-api name

Updated video lecture

Learn to use lightning record form

How to use schema fields and create template

To create record

To update record with page context in record detail page

Use picklist mappings

Student table

Fields:

Age number

Studentemail email

Dateofjoining date

confirmed boolean

Comments textarea

Country

City

Student marks table

Fields:

MD to studentmaster

Marks number

Subject picklist

Year number

1. Students mark should have 1 semesters  and marks against one subject will be once a year.

and Student age cannot be less than 19

2. Students should be marked as pass or fail on average marks of 35 across a years records

3. Students who have more than 2 marks or given 2 subjects whether pass of fail,cannot be deleted for the current year

4.background check failed approval process students cannot be  confirmed again ,using validation rule

5. Visualforce UI for student master and marks using custom controller to save ,edit,delete data

6. Create many to many object finalresults__c ,which will have the following schema

   MD to student master

   md to student marks

   Year

   Pass or Fail(This will be based on an average marks field of 35 for the year,also an email

    will be sent out to student with the result for the year,whether he has passed or failed)

   Average marks for the year(this will be calculated from the marks object and stored here

   either via config or apex)

7. When new student is created

    WEclome kit email should be sent out

    Confirmed flag should be true

    It should be submitted to approval for backgroud and visa check

    Task should be created to make new id

    Create new contact record for student created

8 Build approval process for student for visa and degree check

9. Create LWC  with apex class for students and marks forms.

These scenarios can be resolved using a combination of validation,workflow,master detail relation

   triggers and LWC.