Passing values between pages in Visualforce

I read a lot of information over the web scattered here and there. So I decided to blog about this. Often developers try to figure out what are the different ways through which values can be passed between pages in Visualforce. Well, there might be a number of them, but I would like to talk about the two most common ways to transfer data between the Visualforce web pages.


Method 1. Passing variable value between two pages that implement the same controllers and extensions.
Method 2. Passing values using a Querystring.


Method 1


In order to use the first method above, we need to ensure that the two pages in context need to have the same controller. This might be a Standard controller or a Custom controller.


Say we have to pages Page1 and Page2. Let the Visualforce syntax be as below:


Code for Page1
<apex:page controller="customcontroller1">
   <apex:inputtext id="inpEmployeeName" value="{!EmployeeName}"/><br/>
   <apex:CommandButton value="Next" action="{!next}" id="cmdNext" />
</apex:page>


Code for Page2

<apex:page controller="customcontroller1">

   .The employee name is {!EmployeeName}

</apex:page>

Code for customcontroller1

public with sharing customcontroller1

{

  public string EmployeeName {get;set;} 

  

  // Function for navigating to next page

  public PageReference next()

  {

     PageReference nextpage = new PageReference('/apex/Page2');

     return nextpage;

  }

}

Now there are a few points worthy to note out here. You need to be careful of the method nextpage.setRedirect(true) , a method used to redirect from one page to another. Use it only when you use querystrings in the URL. If you use this method in the method above, it will wipe out all the data stored in variables in page1 being transferred to page2, as page2 in such a scenario will loose all the variable data of the controller, when this page2 loads.

Method 2

This method involves transferring variable data from one page to another, using a query string. This method should be used when the controller of the pages are different. See example below:

Say we have two pages, Page3 and Page4.

Code for Page3

<apex:page controller="customcontroller3">

   <apex:inputtext id="inpEmployeeName" value="{!EmployeeName}"/><br/>

   <apex:CommandButton value="Next" action="{!next}" id="cmdNext" />

</apex:page>

Code for Page4

<apex:page controller="customcontroller4">

   .The employee name is {!EmployeeName}

</apex:page>

Code for customcontroller3

public with sharing customcontroller3

{

  public string EmployeeName {get;set;} 

  // Function for navigating to next page

  public PageReference next()

  {

     PageReference nextpage = new PageReference('/apex/Page4?EN=' + EmployeeName);

     return nextpage.setRedirect(true); //Note that setRedect method is used here

  }

}

Code for customcontroller4

public with sharing customcontroller4

{

  public string EmployeeName {get;set;} 

  

  //Constructor

  public customcontroller4()

  {

    String strEmpName = ApexPages.currentPage().getParameters().get('EN');

  }

 }

This way, you can transfer data from a page to another even if they don't have the same controller. 

There is another way to transfer data between pages, and that is using Javascript and hidden fields in the form. I will blog on that in my coming posts.

Till then, happy reading. Cheers!

Vishal

Working with the Salesforce.com Database

Salesforce.com comes with its own database. Salesforce defines a database as "an organized collection of information". Databases in the real world are used to pile up information about real world objects such as employees, students, account holders, company names, industry related data etc. In a typical database such as an Oracle SQL Server or a  Microsoft SQL Server, a database is a collection of related tables, collectively called a schema. Each table contains information about one subject such as student information, where in the table name will typically be named as 'student' or 'table_student' because student is the main subject of importance in this table. The subject of importance is also known as an entity. When we talk about the same stuff in the world of Salesforce, we call this as an object. So basically we can also say that an object is a category of information.

It is worth to know here that there are pre-built objects in the Salesforce.com platform, that we call as sObjects (a short for Salesforce Objects). Beyond these pre-built objects, developers can create custom objects of their own. Thats the power of Salesforce.

A table is comprised of rows (the records) and columns (the fields). The same way, an object is also comprised of records and fields. 

The Salesforce.com is powered by the Force.com platform, a platform through which applications can be built using in built wizards, or through the combination of Visualforce (the pages) and Apex (the programming language). Apex is leveraged by a query language called SOQL (Salesforce Object Query Language) that allows querying objects in Salesforce.

However, it is important to note that SOQL does allow DML statements (such as insert, update, delete, upsert) but does not allow DDL statements (such as create, drop, alter).

Now that objects have been discussed, lets talk about what are fields. In short, fields are the column headers that signify what data about that object is there in that column. For example, we can have an object by the name "Employee" and we can have fields defined against this object, such as "Employee Name", "Age", "Designation", "DOB", "DOJ", "Department" etc. 

Moving on to the next level, a database comprises of multiple objects. This is to ensure that everything (ie every piece of data) is not packed into one object. For such scenarios, Salesforce.com allows relating tables. For example, we may associate a Manager with an Employee. That means we are talking about two objects here, the Employee object (that will house all the employees information) and the Manager object (that will house all the managers information).

Now to relate objects, we need unique columns in each table. This can be done by marking one column in a table as a primary key, and the corresponding column on the other object as the foreign key. 


In my next posts, I'm going to talk about the different types of relationships that can be created using the Force.com platform.