Difference between the way object values are fetched in Salesforce

Question

In salesforce any object attribute value(let say case recordtypeid), can be fetched using two ways,

{!$case.RecordTypeid} - with dollar sign

{!Case.RecordTypeid} - without dollar sign

Can anybody help what the difference between both and also which one to use when?

Answer 1

Generally one is a global variable and another is a merge field.

• The global variable {!$Label.MyLabel__c } is a kind of merge field that is a built in feature of salesforce
• A normal merge field {!Account.Name} can be defined by user (apex controller, standard controller, ...)

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The ! sign followed by $ is a Global Variable.

Use global variables to reference general information about the current user and your organization on a page.

That means that you can access some information from some objects on the visualforce page or in a apex code directly without having to query a database (check out a list with all global variables here). Additionally read this useful topic for better understanding what a gloab variable is: "Understanding Global Variables"

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The ! sign alone (without $) is a Merge Field.

For example if your vialforce page use a standard account controller, you can access fields from that object directly using this syntax: {!Account.Name}

Or you can define some variable in APEX controller and reference it on the viasualforce page using this syntax too.