How to build a SalesForce Custom Button with "validation" rules

Question

Need a custom botton on an opportunity page to execute a task only after a set of validation checks have been preformed. Meaning the button will only function IF a list of fields and pick-lists have correct selections. Button should be unavailable for selection if these fields are not selected.

Further, botton should change the executable task if a field is populated versus non populated

How do I make this happen?

Answer 1

You're going to want to create a button that uses the Javascript API to make the checks and then take action accordingly. You (STILL, after years and years of the Idea being a top voted customer Idea) can't make buttons appear/disappear on a single page layout, but the workaround is either to make the button alert the user if the action is invalid, or (much more involved) use the fields to switch the record type of the record and use 2 different page layouts, one with the button and one without. You can use a jQuery hack to hide buttons but it's not really a supported feature and I generally don't recommend it.

You'll want to look at the docs for the Javascript API. A pretty decent example of the type of thing you want to do can be found here.

Answer 2

This may not be exactly what you're looking for, but it'll get you close and won't require a developer.

Instead of creating a button, you can create a formula field that displays a link to create the task, but only if certain criteria or met. For example

IF(
  ISBLANK(Your_Field__c)
, 'Please populate your field before taking action'
, HYPERLINK('/urlforyouraction?id=' + Id, 'Take the action')
)

Answer 3

Apex Approach: So here is my template for Apex via Custom Buttons as opposed to using JavaScript. It leverages Standard Controller methods as much as possible. Note that it is not possible to perform the update of the record in the same method due to security issues. Hope this helps!

In a valid case it shows this...

In an invalid case it shows this...

Standard Controller Class:

public with sharing class ValidationController 
{
    private ApexPages.StandardController standardController;

    public ValidationController(ApexPages.StandardController standardController)
    {
        // Configure fields to query and validate (alternative to SOQL)
        this.standardController = standardController;
        if(!Test.isRunningTest())
            this.standardController.addFields(
                new List<String> { Schema.Test__c.A_Number__c.getDescribe().getName() });   
    }

    public PageReference validate()
    {
        // Validate record
        Test__c test = (Test__c) standardController.getRecord();
        if(test.A_Number__c != 42)
            test.A_Number__c.addError('Not the answer to life the universe and everything!');

        // If no errors display confirmation message
        if(!ApexPages.hasMessages())
            ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.Info, 'All is well, go ahead and click Update.'));

        return null;
    }

    public PageReference validateAndUpdate()
    {
        // Validate and redisplay if errors
        validate();
        if(ApexPages.hasMessages(ApexPages.Severity.Error))
            return null;

        // Update the record and call standard controller save
        Test__c test = (Test__c) standardController.getRecord();        
        test.Date__c = System.today();
        return standardController.save();
    }
}

You can view the test methods here.

Visualforce Page:

<apex:page standardController="Test__c" extensions="ValidationController" tabStyle="Test__c" action="{!validate}">
    <apex:sectionHeader title="Test" subtitle="{!Test__c.Name}"/>
    <apex:pageMessages />
    <apex:form >
        <apex:commandButton value="Update" action="{!validateAndUpdate}"/>
        <apex:commandButton value="Back" action="{!cancel}"/>
    </apex:form>
</apex:page>

You can then go to Custom Buttons on your object and add a Visualforce based custom button.