How Do “With” and “Without Sharing” Work in Apex?

Question:

I’m trying to solidify my understanding of the “With Sharing,” “Without Sharing,” and unspecified sharing rules in Salesforce Apex. Below is my current understanding, followed by some scenarios and questions for clarification:

Notes on Sharing Rules:

1. With Sharing:
   • Implies “with security settings enforced”, specifically respecting OWDs and Sharing Rules.
   • Question: Does this also apply to Object-Level Security (OLS) and Field-Level Security (FLS)?
2. If a class is declared with sharing, the sharing settings apply to:
   • All code in the class (including initialization, constructors, and methods).
   • Exception: Inner classes do not inherit sharing settings from their outer class.
3. Unspecified Sharing:
   • Classes not explicitly declared with or without sharing run in system mode (without sharing).
   • However, if a “with sharing” class calls such a class, it executes in “with sharing” mode by default.
4. Inheritance of Sharing Rules:
   • If class B extends class A, B inherits A’s sharing mode.
   • Inner classes of B do not inherit B’s sharing settings.
5. Method Invocation Across Classes:
   • If a with sharing class calls a without sharing class, the called methods execute in the mode of their defining class (in this case, without sharing).

Scenarios for Validation:

I have three classes:

public with sharing class A {}
public without sharing class B {}
public class C {} // Unspecified sharing

Based on the above, I have the following scenarios:

1. class B extends class A:
   • Code in class B executes in “with sharing” mode (inherits parent class A’s mode).
2. class B calls class A:
   • Called code in class A executes in “with sharing” mode (mode of the defining class).
3. class C calls class A:
   • Called code in class A executes in “with sharing” mode (mode of the defining class).
4. class C extends class A:
   • Code in class C executes in “with sharing” mode (inherits parent class A’s mode).
5. class A calls class C:
   • Code in class C executes in system mode (since class C is unspecified and runs without sharing).
6. class A extends class C:
   • Code in class A executes in “without sharing” mode (inherits parent class C’s mode).
   • Question: Is this understanding correct?

Additional Questions:

1. What are common use cases where “with sharing” and “without sharing” rules are explicitly applied?
2. How do these sharing settings apply in the context of Visualforce Controller Classes and Controller Extensions?

Keywords: Apex, sharing rules, with sharing, without sharing, unspecified sharing, inheritance, Visualforce controllers, Salesforce Apex security.

Answer

1. With Sharing

When a class is declared with the with sharing keyword, it enforces the sharing rules of the current user. This includes organization-wide defaults (OWD) and sharing rules but does not automatically enforce object-level security (OLS) or field-level security (FLS). Developers must handle OLS and FLS programmatically.

public with sharing class ClassA {
    public void methodA() {
        // This query respects sharing rules
        List<Account> accounts = [SELECT Id FROM Account];
    }
}

2. Without Sharing

A class declared with the without sharing keyword explicitly ignores sharing rules. It executes in system mode, bypassing the user’s sharing rules. This is useful for system processes or operations that require elevated access.

public without sharing class ClassB {
    public void methodB() {
        // This query ignores sharing rules
        List<Account> accounts = [SELECT Id FROM Account];
    }
}

3. Unspecified Sharing (Default Behavior)

If a class does not explicitly declare with sharing or without sharing, it executes in system mode (ignoring sharing rules) except in certain contexts, like Execute Anonymous or Chatter, where it behaves as with sharing. When such a class is invoked by another class with sharing, it inherits the caller’s sharing mode.

public class ClassC {
    public void methodC() {
        // Executes in system mode unless called from a `with sharing` context
        List<Account> accounts = [SELECT Id FROM Account];
    }
}

Behavior in Scenarios

Scenario 1:
If Class B extends Class A (with sharing), Class B inherits the sharing settings of Class A. This means all methods in Class B execute in with sharing mode.

public with sharing class ClassA {}
public without sharing class ClassB extends ClassA {} // ClassB now enforces sharing rules

Scenario 2:
If Class B calls a method in Class A (with sharing), the method executes in with sharing mode, respecting sharing rules.

ClassA a = new ClassA();
a.methodA(); // Executes in `with sharing` mode

Scenario 3:
If Class C (unspecified sharing) calls Class A (with sharing), the method in Class A executes in with sharing mode, inheriting its own declaration.

ClassA a = new ClassA();
ClassC c = new ClassC();
c.someMethod(); // Method in ClassA respects its `with sharing` mode

Scenario 4:
If Class A (with sharing) calls Class C (unspecified sharing), Class C executes in system mode unless it is called from an environment like Execute Anonymous, where it behaves as with sharing.

ClassA a = new ClassA();
a.callClassC(); // ClassC executes in system mode

Scenario 5:
If Class A extends Class C (unspecified sharing), Class A’s behavior depends on its declaration. If Class A is declared with sharing, it overrides Class C’s default behavior.

public class ClassC {}
public with sharing class ClassA extends ClassC {} // ClassA enforces sharing rules

Use Cases for Sharing Settings

• Use with sharing for user-facing operations, such as Visualforce pages or Lightning components, where data visibility must adhere to the user’s permissions.
• Use without sharing for system-level processes, like logging, data cleanup, or administrative tasks, where bypassing sharing rules is necessary.

In Visualforce Controller Classes and Extensions, sharing settings are crucial. Controllers that directly fetch or update user data should generally use with sharing to ensure adherence to user permissions. However, controller extensions designed for administrative functions might use without sharing for broader access.

These rules provide a robust mechanism to control data access in Salesforce while balancing flexibility and security.

Summing Up

In Salesforce Apex, sharing settings dictate how data access is controlled during code execution.

• With Sharing enforces user-specific sharing rules, such as organization-wide defaults and sharing rules. It is ideal for user-facing operations to respect data visibility.
• Without Sharing bypasses sharing rules, allowing system-level processes to execute without restriction.
• Unspecified Sharing defaults to system mode but inherits the sharing mode of the caller when invoked from a with sharing context.

Sharing settings do not automatically enforce object-level or field-level security, requiring explicit handling by the developer. When classes interact, the sharing mode depends on their declarations and context, ensuring flexible yet secure access to data. For Visualforce controllers and extensions, using with sharing is common unless broader access is necessary for administrative tasks.

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