PDI Exam Questions Tutorials

 The method must be decorated with @AuraEnabled to make it accessible from a Lightning web component. The @AuraEnabled annotation enables client- and server-side access to an Apex controller method. Without this annotation, the Lightning web component can’t call the Apex method. The cacheable=true attribute is optional and indicates whether the method can be cached by the client. The method can return any data type that can be serialized into JSON, such as a JSON object, a JSON array, a primitive type, or a custom type. The method does not need to return a string of a serialized JSON array, as the framework handles the serialization and deserialization automatically. References:

• Lightning Web Components Developer Guide: Call Apex Methods, pages 1-2
• Apex Developer Guide: Annotation AuraEnabled, page 1
• Trailhead: Platform Developer I Certification Study Guide: Lightning Web Components, unit 5

 A standard list controller provides a list of records of a specific object type, such as Contact, and allows you to create Visualforce pages that can display or act on that data1. A standard list controller is suitable for this purpose, because it can easily query the contacts owned by the current user and display them in a table or list. A standard list controller also supports pagination, sorting, filtering, and mass actions2. A standard controller provides access to a single record of a specific object type, such as Account, and is not suitable for displaying a list of records1. A lightning controller is a JavaScript controller that handles user interactions and events in a Lightning web component, and is not related to Visualforce pages3. A custom controller is an Apex class that implements all the logic for a Visualforce page, and requires writing more code than using a standard list controller1. References:

• Standard Controllers and Standard List Controllers | Visualforce Developer Guide | Salesforce Developers
• Using Standard List Controllers | Visualforce Developer Guide | Salesforce Developers
• Lightning Web Components Developer Guide | Salesforce Developers

 In order to update a record of a junction object, you must have Read/Write access on the primary relationship and Read/Write access on the junction object. A junction object is a custom object that is used to create a many-to-many relationship between two other objects via two master-detail relationships. The primary relationship is the first master-detail relationship that is created on the junction object, and the secondary relationship is the second master-detail relationship that is created on the junction object. To update a record of a junction object, you need to have Read/Write access on both the junction object and the primary relationship, because:

• Read/Write access on the junction object allows you to modify the fields and values of the junction object record, such as the name, description, or custom fields.
• Read/Write access on the primary relationship allows you to change the parent record of the junction object record, which is also known as reparenting. Reparenting is the process of moving a child record from one parent record to another in a master-detail relationship. Reparenting is not allowed by default in master-detail relationships, but it can be enabled by selecting the Allow reparenting option on the relationship field.

Read access on the primary relationship and Read/Write access on the secondary relationship are not sufficient to update a record of a junction object, because:

• Read access on the primary relationship does not allow you to change the parent record of the junction object record, which may be necessary for some updates. For example, if you want to move an OrderItem record from one Order record to another, you need to have Read/Write access on the primary relationship between OrderItem and Order.
• Read/Write access on the secondary relationship does not affect the update of the junction object record, because the secondary relationship is not involved in the update operation. The secondary relationship is only used to associate the junction object record with another parent record, but it does not allow you to modify the junction object record itself.

References: Junction Object, Reparent Records in Master-Detail Relationships, Prepare for Your Salesforce Platform Developer I Credential

The test method fails in the sandbox test framework because it relies on existing data in the sandbox, which may not be consistent or available for the test execution. The Apex test framework uses a separate test data context that is rolled back after the test execution, so any data that is queried or inserted by the test method must be created within the test method or by using the @testSetup annotation. The Execute Anonymous window, on the other hand, runs the Apex logic in the current user context and can access the existing data in the sandbox. Therefore, the Apex logic may succeed in the Execute Anonymous window but fail in the test framework. References:

• Apex Testing (Salesforce Developer Documentation)
• Isolation of Test Data from Organization Data in Unit Tests (Salesforce Developer Documentation)
• Free Salesforce Platform Developer 1 Practice Exam (With Answers) (Salesforce Ben)