Getting Custom Field Id without hardcoding through Tooling API (Without Http Callout also)

Hi,

We can get custom field ids for URL hacking to auto populate through Tooling API as shown below.

Apex Code:

List<FieldDefinition> fieldList =  [SELECT DurableId,QualifiedApiName FROM FieldDefinition WHERE EntityDefinition.QualifiedApiName ='Account'and QualifiedApiName='NoofEmployees__c'];

String NoofEmployeesId = fieldList[0].DurableId.split('\\.')[1];

Visualforce Page (Java Script):

<script type="text/javascript">

            var __sfdcSessionId = '{!GETSESSIONID()}';

</script>

<script src="../../soap/ajax/38.0/connection.js" type="text/javascript"></script>

<script>

var qr = sforce.connection.query("SELECT DurableId,QualifiedApiName FROM FieldDefinition WHERE EntityDefinition.QualifiedApiName ='Account'and QualifiedApiName='NoofEmployees__c'" );

              var NoofEmployeesId = qr.getArray("records")[0].DurableId.split('.')[1];

 </script>