Passing attributes to components

Visualforce pages can pass parameters to components via attributes. A component declares the attributes that it is able to accept, including information about the type and whether the attribute is mandatory or optional. Attributes can be used directly in the component or assigned to properties in the component's controller.

In this recipe we will create a Visualforce page that provides contact edit capability. The page utilizes a custom component that allows the name fields of the contact, Salutation, First Name, and Last Name, to be edited in a three-column page block section. The contact record is passed from the page to the component as an attribute, allowing the component to be re-used in any page that allows editing of contacts.

How it works…

Opening the following URL in your browser displays the ContactEdit page: https://<instance>/apex/ContactEdit.

Here, <instance> is the Salesforce instance specific to your organization, for example, na6.salesforce.com.

The custom component that renders the input fields in the Name section defines a single, required attribute of type Contact.

<apex:attribute name="Contact" type="Contact" 
    description="The contact to edit" required="true" />

Tip

The description of the attribute must always be provided, as this is included in the component reference. The type of the attribute must be a primitive, sObject, one-dimensional list, map, or custom Apex class.

The Contact attribute can then be used in merge syntax inside the component.

<apex:inputField value="{!Contact.Salutation}"/>
<apex:inputField value="{!Contact.FirstName}"/>
<apex:inputField value="{!Contact.LastName}"/>

The page passes the contact record being managed by the standard controller to the component via the Contact attribute.

<c:ContactNameEdit contact="{!Contact}"/>