Introduction

In real-world Salesforce applications, pages rarely work with a single record. Most scenarios involve multiple records, such as lists of Accounts, Contacts, or custom object data.

To manage this data effectively, Visualforce relies on Apex collections, primarily Lists, which are passed from controllers to Visualforce pages for display and processing.

What are Lists and Collections in Apex?

In Apex, a collection is a variable that can store multiple values.

Common collection types include:

● List
● Set
● Map

In Visualforce development, Lists are the most commonly used collection type.

Why Lists Are Important in Visualforce

Lists are important because they:

● Store multiple Salesforce records
● Enable bulk data processing
● Support iteration in Visualforce pages
● Improve performance and scalability

Declaring a List in a Controller

A list is declared in an Apex controller to hold records.

Example:

public List<Account> accountList { get; set; }

This list can store multiple Account records.

Populating a List Using SOQL

Lists are commonly populated using SOQL queries.

Example:

accountList = [
    SELECT Id, Name, Industry
    FROM Account
    LIMIT 10
];

Passing Lists from Controller to Visualforce

Once populated, lists are automatically available to the Visualforce page through data binding.

Example:

<apex:repeat value="{!accountList}" var="acc">
    {!acc.Name}
</apex:repeat>

Displaying Lists Using `<apex:repeat>`

<apex:repeat> is used to iterate through lists.

It allows:

● Looping through records
● Custom layout design
● Flexible UI rendering

This is ideal for non-tabular layouts.

Displaying Lists Using `<apex:dataTable>`

<apex:dataTable> is used for structured table layouts.

It provides:

● Rows and columns automatically
● Clean, readable tables
● Salesforce-style UI

This is best for tabular data.

Handling Empty Lists

Controllers should handle scenarios where lists are empty.

Best practices include:

● Initializing lists in constructors
● Checking list size before rendering
● Displaying user-friendly messages

This improves user experience.

Working with Lists in Action Methods

Lists can be processed inside controller methods.

Common operations include:

● Looping through records
● Updating values
● Performing validations

Example:

for(Account acc : accountList) {
    acc.Industry = 'Technology';
}

Updating Records from Lists

Lists allow bulk updates.

Example:

update accountList;

This updates all records in one operation.

Performance Considerations with Lists

When handling lists:

● Avoid SOQL inside loops
● Limit number of records
● Retrieve only required fields
● Use bulk operations

This helps prevent governor limit issues.

Lists vs Single Record Variables

Key differences include:

● Lists store multiple records
● Single variables store one record
● Lists support iteration
● Lists enable bulk operations

Common Mistakes Beginners Make

● Not initializing lists
● Querying too many records
● Using SOQL in loops
● Forgetting to make lists public

Best Practices for Handling Lists and Collections

● Always initialize lists
● Use Lists instead of arrays
● Keep list size manageable
● Follow bulkification principles
● Maintain clean data binding

Real-World Use Cases

Lists and collections are used for:

● Displaying record lists
● Bulk record updates
● Report-like pages
● Dashboard-style Visualforce pages

Conclusion

Handling lists and collections is a fundamental skill in intermediate Visualforce development. By using Apex lists efficiently and binding them properly to Visualforce components, developers can build scalable, high-performance, and user-friendly applications. Mastering this concept prepares developers for advanced data handling scenarios in Salesforce.

VF Page Beginner to Advance

Handling Lists and Collections