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FKFieldName

property FKFieldName: string read

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := Dataview.FKFieldName;
  if Value = '' then
    LogWarning('The current SQL view has no initialised foreign-key field.');
end;

Usage​

FKFieldName returns the cached SQL field name of the first configured primary/foreign or foreign-key field in the active view.

Behaviour

  • A non-empty result is cached and returned without another scan.
  • No qualifying descriptor, an inactive/not-yet-opened view or an empty SQL field name returns an empty string.
  • An empty result is not permanently cached, so a later read after activation can succeed.

Important usage notes

  • The getter stops at the first qualifying descriptor; composite and additional foreign keys are not represented.
  • The non-empty cache is never cleared by SQL/link changes, deactivation or primary-key-list recreation. Reconfiguring a live view can therefore leave a stale name.
  • The returned name is metadata, not validated SQL text. Do not concatenate it with untrusted text or assume it is quoted for a separately constructed statement.

Errors

The getter normally returns empty rather than raising when metadata is unavailable. Failures during view activation/key creation are handled by that lifecycle and can leave the list empty.

Usage notes

Read this property after the view has opened. For multiple links, use the configured data definition rather than treating this convenience value as a complete relationship description.

Additional Technical Info​

FKFieldName returns the dataset/SQL field name for the first key descriptor classified as a primary/foreign key or foreign key. It is useful when a configured SQL view has a conventional first master-detail link, but it is not a list of every foreign key.

The example reads the name after the host has prepared the view. It is source-reviewed and was not executed by the documentation workflow.

The result is the selected TdaField.SQLFieldName, which is the name used by Query's dataset field rather than necessarily the physical database column expression.

Implementation

The getter checks its private cache. While the cache is empty, it scans the view's primary-key descriptor list in order and stops at the first descriptor whose type is fftPrimaryForeignKey or fftForeignKey. It returns that descriptor's SQLFieldName. The descriptor list is recreated when the view is activated and deleted when it is closed.

Side effects

Reading scans current key metadata only when the cache is empty. It does not move Query, resolve the master field or update the database.

Performance and concurrency

The first successful read is linear in the small primary-key list; cached reads are constant-time. The cache and key list are unsynchronised and belong to the owning flow.

Created 2026-07-15