lightning web component - quick action get record Id

A Quick action can invoke an LWC on record pages. 

There are two types of action: Screen & Headless. 

Regarding how to create quick actions, steps are as below:

1, configuration: 

    https://developer.salesforce.com/docs/component-library/documentation/en/lwc/lwc.use_quick_actions

2. create Quick action

3. Setup->Account->Botton,Links, and Actions->new Action-> Action Type: Lightning Web Component.

 

RecordId:

In Headless, we can easily get recordId from invoke method. 

import { LightningElement, api } from "lwc";

export default class HeadlessSimple extends LightningElement {
    @api recordId  
    @api invoke() {
    console.log(this.recorId);
  }
}

However, In screen action, we can't get recordId. now mater 
connectCallBack() renderedCallBack(). There are severl way to get 
recordId.

1. using setter, getter.
 
    _recordId;

    @api set recordId(value) {
    // get contacts
    this._recordId = value;
...
}

    get rcordId(){
    return this._recodId;
}


2. get in the renderedCallBack();
    this way, we muct use the recordId in html file. like:
  <div style="display: none">{recordId}</div>
    and in js file: 
 

 @recordId;
 isFirst = true;
renderedCallback() {
    if(this.recorId &&  isFirst){
    ...

    isFirst = false;
    }
    
}

3. using CurrentPageReference to get recordId.