Apex Developer Guide

Apex Developer Guide
Release Notes
Getting Started with Apex
Writing Apex
Data Types and Variables
Control Flow Statements
Classes, Objects, and Interfaces
Classes
Interfaces
Keywords
Annotations
Classes and Casting
Differences Between Apex Classes and Java Classes
Class Definition Creation
Namespace Prefix
Using the System Namespace
Using the Schema Namespace
Namespace, Class, and Variable Name Precedence
Type Resolution and System Namespace for Types
Apex Code Versions
Lists of Custom Types and Sorting
Using Custom Types in Map Keys and Sets
Working with Data in Apex
Document Your Apex Code
Running Apex
Debugging, Testing, and Deploying Apex
Apex Reference
Appendices
PDF

Note: This release is in preview. Features described here don’t become generally available until the latest general availability date that Salesforce announces for this release. Before then, and where features are noted as beta, pilot, or developer preview, we can’t guarantee general availability within any particular time frame or at all. Make your purchase decisions only on the basis of generally available products and features.

Namespace Prefix

The Salesforce application supports the use of namespace prefixes. Namespace prefixes are used in managed AppExchange packages to differentiate custom object and field names from names used by other organizations.

When creating a namespace, use something that’s useful and informative to users. However, don’t name a namespace after a person (for example, by using a person's name, nickname, or private information). Once namespaces are assigned, they cannot be changed.

Important

After a developer registers a globally unique namespace prefix and registers it with AppExchange registry, external references to custom object and field names in the developer's managed packages take on the following long format:

1namespace_prefix__obj_or_field_name__c

These fully qualified names can be onerous to update in working SOQL or SOSL statements, and Apex once a class is marked as “managed”. Therefore, Apex supports a default namespace for schema names. When looking at identifiers, the parser assumes that the namespace of the current object is the namespace of all other objects and fields unless otherwise specified. Therefore, a stored class must refer to custom object and field names directly (using obj_or_field_name__c) for those objects that are defined within its same application namespace.

In managed package Apex, that default resolution can cause duplicate field name errors if a subscriber creates a local custom field with the same API name as a packaged field. To control how unqualified and namespace-qualified field names resolve in dynamic SOQL, see Prevent Field Name Collisions in Managed SOQL Queries.

Only use namespace prefixes when referring to custom objects and fields in managed packages that have been installed to your organization from the AppExchange.

Tip

Using Namespaces When Invoking Package Methods

To invoke a method that is defined in a managed package, Apex allows fully qualified identifiers of the form:

1namespace_prefix.class.method(args)

Versioned Behavior Changes

In API version 34.0 and later, Schema.DescribeSObjectResult on a custom SObjectType includes map keys prefixed with the namespace, even if the namespace is that of currently executing code. If you work with multiple namespaces and generate runtime describe data, make sure that your code accesses keys correctly using the namespace prefix.