apex:define Component

The apex:define component is a visualforce component in Salesforce that enables defining a variable used in a Visualforce page that can be accessed by other visualforce components on the page.

Syntax

The syntax for apex:define is as follows:

<apex:define name="variableName" value="{!variableValue}"/>

Example

Consider the following example of defining a variable named myVariable of type String in a Visualforce page:

<apex:define name="myVariable" value="Hello World!"/>

This defines a variable named myVariable with a value of Hello World!.

Explanation

The apex:define component is used to define a variable in a Visualforce page. Once defined, the value of this variable can be accessed by other components on the page. The name attribute specifies the name of the variable, and the value attribute specifies the initial value of the variable.

Use

The apex:define component can be used to define variables that are used by other Visualforce components on the same page. This is useful when multiple components on the same page need to share a common variable.

Important Points

• The apex:define component can only be used within a Visualforce page, and cannot be used in other contexts like Visualforce components or Apex classes.
• The name attribute must be unique within the Visualforce page.
• The value attribute must be in one of the following formats: {!variable}, "literal", or {!variable.property}. The value can also be a formula expression or a function result.

Summary

The apex:define component is used to define a variable in a Visualforce page that can be accessed by other Visualforce components on the same page. The name attribute specifies the name of the variable and the value attribute specifies the initial value of the variable. This component is useful when multiple components on the same page need to share a common variable. To use apex:define, you must use it within a Visualforce page and the name attribute must be unique within the page.