Custom Adapter for Salesforce Connect

Your users and the Lightning Platform interact with the external data via external objects. For each of those interactions, Salesforce Connect invokes methods in the Apex classes that compose the custom adapter. Salesforce invokes the custom adapter’s Apex code each time that:

• A user clicks an external object tab for a list view.
• A user views a record detail page of an external object.
• A user views a record detail page of a parent object that displays a related list of child external object records.
• A user performs a Salesforce global search.
• A user creates, edits, or deletes an external object record.
• A user runs a report.
• The preview loads in the report builder.
• An external object is accessed via flows, processes, APIs, Apex, SOQL, or SOSL.
• You validate or sync an external data source.

Apex code can access external objects, but some limitations and requirements apply.

• To understand the limitations on Apex code accessing external objects, see Apex Considerations for Salesforce Connect External Objects.
• To know how to use a custom adapter for Salesforce Connect, see Get Started with the Apex Connector Framework.

• External IDs for External Objects in Salesforce Connect—Custom Adapter
  When you access external data with a custom adapter for Salesforce Connect, the values of the External ID standard field on an external object come from the DataSource.Column named ExternalId.