You need Lightning Message Channel for Lightning Web Component Message Service to work. Below are the steps with which you can create Lightning Message Channel.
Step 1: Create a folder with name: “messageChannels”
Step 2: Create a file with any name followed by an extension “.messageChannel-meta.xml”
Ex: Sample_Channel_File.messageChannel-meta.xml
Step 3: Below is a simple code
<?xml version="1.0" encoding="UTF-8"?>
<LightningMessageChannel xmlns="http://soap.sforce.com/2006/04/metadata">
<masterLabel>Sample Channel File</masterLabel>
<isExposed>true</isExposed>
<description>This is a sample Lightning Message Channel.</description>
<lightningMessageFields>
<fieldName>a_Variable1</fieldName>
<description>Variable 1 Description - optional</description>
</lightningMessageFields>
<lightningMessageFields>
<fieldName>a_Variable2</fieldName>
<description>Variable 2 Description - optional</description>
</lightningMessageFields>
</LightningMessageChannel>
Here, you can add or remove LightningMessageFields as required.
Step 4: Add LightningMessageChannel as type in Package.xml file.
<types>
<members>*</members>
<name>LightningMessageChannel</name>
</types>
Step 5: Deploy the message channel xml file.
- Right Click
- SFDX: Deploy This Source to Org
Note:
To use the channel in visualforce page or Aura component or Web component. You need to use the file name of channel followed by __c
Ex: in above example file name is Sample_Channel_File, so to use this channel you need to mention it as Sample_Channel_File__c
In LWC it will be
import a_LMS_Channel from "@salesforce/messageChannel/Sample_Channel_File__c";
In Aura it will be
<lightning:messageChannel type="Sample_Channel_File__c" aura:id="Sample_Channel_File__ID" onMessage="{!c.a_Method_To_Execute}"/>
In VisualForce page script tag
const GINFO = "{!$MessageChannel.Sample_Channel_File__c}"
Akhil Kulkarni 