Explain The Need Or Importance Of The Controller Extension in Salesforce?

Hi,

Controller Extension is very useful and important concept introduced by the salesforce recently. It gives the power to the programmer to extend the functionality of existing custom controller or standard controller.

A Visualforce can have a single Custom controller or standard controller but many controller extensions.

We can say that the custom extension is the supporter of custom or standard controller.

Consider one example: If there is one controller written and used by the multiple Visualforce pages and one of them needs some extra logic. Then instead of writing that logic to controller class (Which is used by many Visualforce pages) we can create a controller extension and apply to that page only.

Thanks

Hi,

Adding Examples -

Code for Visualforce page

<apex:page Controller="AddmultipleAccountsController">
<apex:form >
<apex:pageBlock >
<apex:pageBlockTable value="{!listAccount}" var="acc">
<apex:column headerValue="Account Name">
<apex:inputField value="{!acc.Name}"/>
</apex:column>
<apex:column headerValue="Account Number">
<apex:inputField value="{!acc.AccountNumber}"/>
</apex:column>
<apex:column headerValue="Account Type">
<apex:inputField value="{!acc.Type}"/>
</apex:column>
<apex:column headerValue="Industry">
<apex:inputField value="{!acc.Industry}"/>
</apex:column>
</apex:pageBlockTable>
<apex:pageBlockButtons >
<apex:commandButton value="Add one more account" action="{!addAccount}"/>
<apex:commandButton value="Save Accounts" action="{!saveAccount}"/>
</apex:pageBlockButtons>
</apex:pageBlock>
</apex:form>
</apex:page>

Code for custom controller:

public class AddmultipleAccountsController {
Account account = new Account();
public list<Account> listAccount{ get; set; }

public AddmultipleAccountsController()
{
listAccount=new list<Account>();
listAccount.add(account);
}

Public void addAccount()
{
Account acc = new Account();
listAccount.add(acc);
}
public PageReference saveAccount() {
for(Integer i=0; i<listAccount.size(); i++)
{
insert listAccount;
}
return Page.Allaccountssaved;    // I am returning another vf page here.
}
}

Hope this helps.