Describe sObjects And Fields In Visualforce Alone

Sunday, August 19, 2012

Well today while trying to retrieve the label of a field dynamically I found a hidden capability of visualforce!
It not only can retrieve the "label" but almost everything that can be retrieved using "DescribeSObjectResult" and "DescribeFieldResult" .

Instead of rushing into the topic proceed step by step.

Example : Dynamically retrieving the label of Account say phone.

<apex:outputLabel value="{!$ObjectType.Account.fields.Phone.label}"/> 

Well we can also retrieve the API name of the field by just changing the "label" with "name"

<apex:outputLabel value="{!$ObjectType.Account.fields.Phone.name}"/> 

Well thats not all you can also get the datatype of the field

<apex:outputLabel value="{!$ObjectType.Account.fields.Phone.type}"/> 

So what we are actually doing here?
Well if we simply write "$ObjectType.Account.fields.Phone" we are actually describing the phone field which is equivalent to "Schema.DescribeFieldResult" now if you see the salesforce doumentation for "Schema.DescribeFieldResult"(http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_methods_system_fields_describe.htm). Now if you see the above page there are lots of methods defined like say  "getLength()" you can simple access the value by dropping the "get" and writing :

<apex:outputLabel value="{!$ObjectType.Account.fields.Phone.length}"/> 

How to do this dynamically?

<apex:outputLabel value="{!$ObjectType.Account.fields[fieldName].label}"/> 

Where "fieldName" is the fieldApi Name.

What else we can do?
Well if you check this page (http://www.salesforce.com/us/developer/docs/api/Content/sforce_api_calls_describesobjects_describesobjectresult.htm) you can almost call every method described in this page. Doing "$ObjectType.Account" actually describes the Account object and now after describing the object you can call almost any of the above methods described in salesforce documentation for "DescribeSObjectResult".

Example 1: Say if I want to retrieve the plural label for sObject "Account" my VF code will be

<apex:outputLabel value="{!$ObjectType.Account.labelPlural}"/>

Example 2 : If I want retrieve the "keyPrefix"

<apex:outputLabel value="{!$ObjectType.Account.keyPrefix}"/>

Like this we can almost get all the properties for a object describe