Create custom system events

Warning: System event handlers (any Apex class that implements the SE_ISystemEventHandler or SE_ISystemEventHandlerWithGetters Apex interfaces) do not support the use of data manipulation language (DML) when processing a system event.

To create a custom system event:

1. Create a System Event (mvn__SE_System_Event__mdt) metadata record. Key fields include:

   • System Event Name - enter a unique API name for the record.

   • Payload Apex Class Name - specify the payload type for the system event. If your custom system event uses a list of SObjects as the payload, leave this field blank. If the system event uses a list of custom Apex class objects as the payload, enter the API name of a custom Apex class. The custom Apex class must implement the SE_ISystemEventApexClassPayload interface:

      global interface SE_ISystemEventApexClassPayload {
          String getUniqueId();
      }

:::: ::: title Payload :::

/** Custom class that implements the SE_ISystemEventApexClassPayload interface */

          public class MyCustomPayload implements SE_ISystemEventApexClassPayload {
          /** Private variable to store this instance's unique Id */
          private String uniqueId;

/** Constructor that initializes the instance with an unique Id */

          public MyCustomPayload() {
          this.uniqueId = UUIDGenerator.generateId();
          }

/** Implementation of the SE_ISystemEventApexClassPayload interface method that returns the unique Id */

          public String getUniqueId() {
          return this.uniqueId;
          }
      }
  ::::

• Payload Apex Class Namespace - enter the namespace of the Apex class defined in the Payload Apex Class Name field.

• Priority - enter the order in which the custom system event should be processed. A system event with a priority of 1 is processed before a system event with a priority of 2.

For a list of all the System Event fields, visit the System Event custom metadata type.

2. Create a System Event Configuration (mvn__SE_System_Event_Configuration__mdt) metadata record record. Key fields include:

   • System Event - associate the System Event metadata record that you created in step 1.

   • Handler Name - enter the API name of the Apex class that implements the associated System Event metadata record. The custom Apex class must implement the SE_ISystemEventHandler interface:

     /**

     • @author
     • @description Interface for the System Events handlers */

      global interface SE_ISystemEventHandler {
          /**
           * Processes the SE_System_Event_Configuration__mdt records for the given new and old objects.
           *
           * The input variables are generic so that any type of payload in the form of an Object/SObject can be passed,
           * the implementation is responsible for casting them to the appropriate type to be able to process them.
           *
           * @param  config         the SE_System_Event_Configuration__mdt being processed
           * @param  newRecords     the list of new/updated payload Objects
           * @param  oldRecordsMap  the map of old SObject records sorted by Id when the routers processes SObjects
           */
          void process(SE_System_Event_Configuration__mdt config, List<Object> newRecords, Map<Id, SObject> oldRecordsMap);
      }

In addition to implementing the SE_ISystemEventHandler interface, the handler can optionally implement the SE_ISystemEventHandlerWithGetters interface. This interface allows the handler to create emails, Salesforce notifications, Chatter posts, and audit logs.

/**

• @author
• @description Interface for the System Event handlers that also implement getters for notification, chatter posts
• and/or SObjects */

      global interface SE_ISystemEventHandlerWithGetters extends SE_ISystemEventHandler {
          /**
           * @return   the List of generated SE_SalesforceNotification records that represent the custom notifications
           */
          List<SE_SalesforceNotification> getSalesforceNotifications();

/**

• @return the List of generated SE_EmailMessage that represent the emails */ List<SE_EmailMessage> getEmailMessages();

/**

• @return the List of generated SE_ChatterFeedPost that represent the chatter posts */ List<SE_ChatterFeedPost> getChatterFeedPosts();

/**

• @return the List of generated generic SObject records to insert (e.g. document audit log entries) */ List<SObject> getSObjects(); }

For a list of all the System Event Configuration fields, visit the System Event Configuration custom metadata type.