Understanding apex:form Component in Visualforce

The <apex:form> component is a must-have wrapper for interactive elements in Visualforce. It allows user input, button actions, and AJAX interactions to be processed by the server.

Why It’s Important

• Enables form submissions to the controller.
• Required for components like <apex:commandButton>, <apex:inputText>, etc.
• Handles page state between requests.

Basic Syntax

xmlCopyEdit<apex:form>
    <!-- input and buttons go here -->
</apex:form>

Example: Simple Form with Input and Button

xmlCopyEdit<apex:page controller="SimpleFormController">
    <apex:form>
        <apex:inputText value="{!name}" label="Enter your name" />
        <apex:commandButton value="Submit" action="{!greetUser}" />
        <p>{!message}</p>
    </apex:form>
</apex:page>

Apex Controller:

apexCopyEditpublic class SimpleFormController {
    public String name { get; set; }
    public String message { get; set; }

    public void greetUser() {
        message = 'Hello, ' + name + '!';
    }
}

Key Points

• Only one <apex:form> per page is best practice, unless needed otherwise.
• Works with AJAX components like <apex:actionSupport> and <apex:actionFunction>.

Use Cases

• Login forms
• Input data submission
• Triggering server-side logic