LWC Syntax Guide

  calling apex class :

1. Import apex method to use 

with name space-- 

import apexMethodName from '@salesforce/apex/Namespace.Classname.apexMethodReference';

without name space:

import apexMethodName from '@salesforce/apex/Classname.apexMethodReference';

2. invoke the method that was imported 

 we have three ways to invoke executed method 

2.1  wire a property 

2.2 wire a function 

2.3 call method imperatively

2.1 example   wire property 

@wire(apexMethod, { apexMethodParams }) propertyOrFunction; 

2.2 example wire function

 @track returnValues;

    @track error;

  @wire(apexMethod, { apexMethodParams })

    wiredFunction({ error, data }) {

        if (data) {

            this.returnValues = data;

            this.error = undefined;

        } else if (error) {

            this.error = error;

            this.returnValues = undefined;

        }

    }

2.3 calling apex imperatively

    @track returnValues;

    @track error;

    handleLoad() {

        apexMethod()

            .then(result => {

                this.returnValues = result;

            })

            .catch(error => {

                this.error = error;

            });

    }