[SalesForce] Retrieve record Id – Visual flow (beta) in Lightning Experience

The Spring '20 release brought the URL hack for prepopulating field values to Lightning. You can now achieve this with custom buttons and links (not Javascript buttons) much like we used to in Classic.

Spring '20 release note: Navigate to a Record's Create Page with Default Field Values

Where: This change applies to Lightning Experience in all editions. This change doesn’t apply to Lightning Out, Lightning communities, or the Salesforce mobile app.

How: To construct a custom button or link that launches a new record with prepopulated field values, use this sample formula:

/lightning/o/Account/new?defaultFieldValues=
    Name={!URLENCODE(Account.Name)},
    OwnerId={!Account.OwnerId},
    AccountNumber={!Account.AccountNumber},
    NumberOfEmployees=35000,
    CustomCheckbox__c={!IF(Account.SomeCheckbox__c, true, false)}

NOTE: URL hacks do not work in lightning experience.

Flow Type: Flow actions support only flows that include screens.

Input Variables Flow actions let you pass the value of the record's ID field into the flow, but that's it. If your flow has a Text input variable called recordId, the action passes the record's ID into that variable at runtime. If not, it doesn't and the flow tries to run anyway.

So the above is relevant only if your'e using screen flows Add a Flow As an Action on a Record

If you do need to use a flow without screens you can leverage lightning components(Embed a Flow in a Custom Lightning Component) to pass the recordId to the flow

<aura:component>
    <aura:handler name="init" value="{!this}" action="{!c.init}" />
    <lightning:flow aura:id="flowData" />
</aura:component>

Controller

({
    init : function (component) {
        // Find the component whose aura:id is "flowData"
        var flow = component.find("flowData");
        // In that component, start your flow. Reference the flow's Unique Name.
        flow.startFlow("myFlow");
    },
})

If you want to end up using in both classic and lighting use a custom button to Embed Flows in Visualforce Pages

<apex:page standardController="Opportunity" tabStyle="Opportunity" >
    <flow:interview name="ModemTroubleShooting">
        <apex:param name="oppId" value="{!Opportunity.Id}"/>
    </flow:interview>
</apex:page>