Apex Method Call In LWC

Apex method Call from LWC :

syntax:
import apexMethodName from '@salesforce/apex/Namespace.Classname.apexMethodName';
Example:

public with sharing class ContactController {
    @AuraEnabled(cacheable=true)
    public static List<Contact> getContactList() {
        return [SELECT Id, Name, Title, Phone, Email, Picture__c FROM Contact WHERE Picture__c != null LIMIT 10];
    }
}

Namespace = The namespace of the Salesforce organization.
Classname = The Name of Apex Class
apexMethodName = Method name to import
apexMethodName = identify the apex method in js.

Expose Apex Methods to Lightning Web Components:

To expose an Apex method to a Lightning web component, the method must be static and either global or public. Annotate the method with @AuraEnabled.

• Primitive—Boolean, Date, DateTime, Decimal, Double, Integer, Long, and String.
• sObject—standard and custom sObjects are both supported.
• Apex—an instance of an Apex class. (Most often a custom class.)
• Collection—a collection of any of the other types.

To use @wire to call an Apex method, you must set cacheable=true.

Enable Client-Side CachingEnable Client-Side Caching:

To improve runtime performance, annotate the Apex method with @AuraEnabled(cacheable=true), which caches the method results on the client. To set cacheable=true, a method must only get data, it can’t mutate (change) data.

In some cases, you know that the cache is stale. If the cache is stale, the component needs fresh data. To query the server for updated data and refresh the cache, call refreshApex(). For information, scroll down to the Refresh the Cache section.

Using Continuations

Use the Continuation class in Apex to make a long-running request to an external Web service.

Continuations use the @AuraEnabled annotation.

@AuraEnabled(continuation=true)

An Apex controller method that returns a continuation must be annotated with @AuraEnabled(continuation=true).

@AuraEnabled(continuation=true cacheable=true)

To cache the result of a continuation action, set cacheable=true on the annotation for the Apex callback method.