If a Salesforce controller has a series of extensions then which extension will execute first?

Hi Tanu,

Multiple controller extensions can be defined for a single page through a comma-separated list.

If both extension having same method, whichever methods are defined in the “leftmost” extension, or, the extension that is first in the comma-separated list will execute first.

For eg:-

Visualforce Page:-

<apex:page standardController="Account"
extensions="ExtOne,ExtTwo" showHeader="false">
<apex:outputText value="{!foo}" />// this formula field first call the foo from ExtOne extension.
</apex:page>

For Extension:-

public class ExtOne {
public ExtOne(ApexPages.StandardController acon) { }

public String getFoo() {
return 'foo-One';
}
}

public class ExtTwo {
public ExtTwo(ApexPages.StandardController acon) { }

public String getFoo() {
return 'foo-Two';
}
}

If both having different method then it will execute based on formula {! } which method you are calling

Extension Example:-

public class OneExt {
public OneExt(ApexPages.StandardController controller) { }
public String getFood() {
return 'OneExt';
}
}

public class TwoExt {

public TwoExt(ApexPages.StandardController controller) {}
public String getFoo() {
return 'TwoExt';
}

}

Visualforce page:-

<apex:page standardController="Account" extensions="ExtOne,ExtTwo" showHeader="false">
<apex:outputText value="{!foo}"/> //This formula field will call  foo() from the TwoExt extension.
</apex:page>