The <apex: attribute> component is another important component that is used for specifying a definition of an attribute on a custom component. The <apex: attribute> can only be a child of a component tag only.
The <apex: attribute> component has the following attributes:
1. access
It is one of the most important attributes that is used for specifying whether we can access this attribute outside of any page in the same namespace or not. The public and global are two possible values for it.
Syntax:
<apex:attribute access="global"></apex:attribute>
2. assignTo
It is of type Object that is used for specifying the setter method. The setter method is responsible for assigning the value of this attribute to a class variable in the associated custom component controller.
Syntax:
<apex:attribute assignTo="{!colorName}"></apex:attribute>
3. default
It is of type string that is used for specifying the default value for this attribute.
Syntax:
<apex:attribute default="red"></apex:attribute>
4. description
It is of type string that is used for specifying the text description of the attribute.
Syntax:
<apex:attribute description="Color of the text."></apex:attribute>
5. id
It is of type string that is a unique identifier for allowing this attribute to be referenced by other tags in the custom component definition.
Syntax:
<apex:attribute id="attributeId"></apex:attribute>
6. name
It is of type string that is used for specifying the name of the attribute. By using the name of the attribute, we can use it in VF markup when the associated custom component includes a value for the attribute.
Syntax:
<apex:attribute name="colorName"></apex:attribute>
7. required
It is of type Boolean that is used for specifying whether the attribute value must be provided by the user or not when the associated custom component is included in a VF page. By default, its value is set to false.
Syntax:
<apex:attribute required="true"></apex:attribute>
8. type
It is of type string that is used for specifying the data type of the attribute. It can be primitives, sObject, one-dimensional lists, maps, or custom apex types.
AD
Syntax:
<apex:attribute type="Account"></apex:attribute>
Let's take an example to understand how we can use the <apex: attribute> component in VF:
ApexAttributeExample.vfp
<!-- create apex page with custom controller and visual force component-->
<apex:page controller="ApexAttributeController">
<!-- use apex form to show the accounts and contacts table-->
<apex:form >
<apex:pageBlock title="Account/Contact Information">
<!-- command button that is responsible for showing accounts in the table-->
<apex:commandButton action="{!getAccounts}" value="Show Accounts"/>
<!-- Embeded Visualforce component-->
<c:apexAttributeComponent accounts="{!accList}"></c:apexAttributeComponent>
<!-- command button that is responsible for showing contacts in the table-->
<apex:commandButton action="{!getContacts}" value="Show Contacts"/>
<!-- Embeded Visualforce component-->
<c:apexAttributeComponent contacts="{!conList}"></c:apexAttributeComponent>
</apex:pageBlock>
</apex:form>
</apex:page>
ApexAttributeComponent.vfc
<!-- Visualforce component starts with apex component -->
<apex:component >
<!--declare and define two apex attributes, i.e., accounts and contacts-->
<apex:attribute name="accounts" type="Account[]" description="Array to store N number of Accounts."/>
<apex:attribute name="contacts" type="Contact[]" description="Array to store N number of Contacts."/>
<apex:pageBlock>
<!-- create a table for showing accounts information -->
<apex:pageBlockTable value="{!accounts}" var="acc">
<apex:column value="{!acc.Name}"/>
<apex:column value="{!acc.AccountNumber}"/>
<apex:column value="{!acc.Phone}"/>
<apex:column value="{!acc.Rating}"/>
<apex:column value="{!acc.Website}"/>
</apex:pageBlockTable>
<!-- create a table for showing contacts information -->
<apex:pageBlockTable value="{!contacts}" var="con">
<apex:column value="{!con.FirstName}"/>
<apex:column value="{!con.LastName}"/>
<apex:column value="{!con.AccountId}"/>
<apex:column value="{!con.Email}"/>
<apex:column value="{!con.Phone}"/>
</apex:pageBlockTable>
</apex:pageBlock>
</apex:component>
ApexAttributeController.apxc
AD
// create ApexAttributeController class to get the list of Accounts and Contacts
public class ApexAttributeController {
public List<account> accList{get;set;}
public List<contact> conList{get;set;}
// create getAccounts() method to get account records
public void getAccounts() {
accList = [select Id, Name, Rating, Phone, AccountNumber, Website From Account];
}
// create getContacts() method to get contact records
public void getContacts() {
conList = [select Id, FirstName, LastName, AccountId, Email, Phone From Contact];
}
}
