How do custom validations in Visualforce Pages?

Implementing validation in Visual Force pages can be tricky as times because individual field support a "required" behavior while you may need something something much more complex than that.

In fact in order for you to be able to validate the data you may need to put of a whole block of code to support it.

Here is how you can add data validation into your Visual Force pages:

1) In order to be able to support this requirement you either need to create a new Controller or extend an existing one.

2) Find out on what events (button click, etc) you need to carry out validation.

3) Write an Apex method for your controller "IsValid" which returns a boolean value indicating whether the validation was successful or not.

4) Put your validation logic in that method and call this method in the chosen events such as button clicks, etc.

Below is as example you can easily test on your own SalesForce Developer portal and learn more:


In this example, only when user selects the last value of the list is not required to provide "Comments" otherwise "Comments" are mandatory!

Visual Force Page Markup Code:

<apex:page controller="ValidationFormPageController" tabStyle="Account"> <apex:sectionHeader title="Validation Test Page"></apex:sectionHeader> <apex:form > <apex:pageBlock title="" id="pageBlock"> <apex:pageBlockButtons location="top"> <apex:outputLabel value="Options: " for="chooseView"></apex:outputLabel> <apex:selectList id="chooseView" value="{!selectedValue}" size="1"> <apex:selectOption itemValue="Value1" itemLabel="Label Value 1"></apex:selectOption> <apex:selectOption itemValue="Value2" itemLabel="Label Value 2"></apex:selectOption> <apex:selectOption itemValue="Value3" itemLabel="Label Value 3"></apex:selectOption> </apex:selectList><br/> <apex:outputLabel value="Comments: " for="theTextArea"></apex:outputLabel> <apex:inputTextarea id="theTextArea" value="{!inputTextValue}" style="{!textAreaStyle}" ></apex:inputTextarea><br/><br/> <apex:commandButton value="Run" action="{!Run}" id="theButton" rerender="pageBlock"></apex:commandButton> </apex:pageBlockButtons> <apex:pageMessages ></apex:pageMessages> </apex:pageBlock> </apex:form> </apex:page>

Visual Force Page Markup Code:

public class ValidationFormPageController { private string textAreaStyle = ''; private string selected_Value = 'Value1'; private string inputTextValue = ''; public string getSelectedValue() { return selected_Value; } public void setSelectedValue(String value) { selected_Value = value; } public string getInputTextValue() { return inputTextValue; } public void setInputTextValue(string Value) { inputTextValue = Value; } public string getTextAreaStyle() { return textAreaStyle ; } public PageReference Run() { if (!isValid()) { //what to show when the data is not valid: ApexPages.addmessage(new ApexPages.message(ApexPages.severity.INFO,'Validation Failed: Comments are required.')); textAreaStyle = 'border-size:2px; border-color:red;border-style:solid;'; return null; } else { // things to do when data is valid. textAreaStyle = ''; } //The rest of your logic return null; } private Boolean isValid() { // this method is called to validate the data entered by user. if (selected_Value != 'Value3') { if (inputTextValue == '') return false; else return true; } else return true; } }