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FieldExists

function FieldExists(const aFieldName: string): Boolean;

Example​

function HasOptionalNote(const View: TdaSQLQueryDataView): Boolean;
begin
  Result := View.FieldExists('OptionalNote');
end;

Usage​

FieldExists tests whether the client dataset contains a physical field name without raising for an ordinary miss.

  • Use for genuinely optional/versioned schema, then access the field once.
  • Treat required configuration fields as errors instead of silently skipping them.
  • Do not use this as value validation; inspect the returned field and IsNull separately.

Additional Technical Info​

FieldExists is the non-raising physical-name probe for a concrete query DataView.

Source-backed behaviour​

The hidden base returns false. Both visible descendants override it with Assigned(FQuery.FindField(aFieldName)). FindField searches ordinary and aggregate fields and returns nil for an absent name. It does not resolve DataPipeline aliases; use the same physical naming rules as FieldByName.

A false result can also reflect that fields have not yet been created/opened for the current view configuration, so lifecycle matters. A true result says only that a field object exists; it does not prove a value is non-null, writable, or mapped to a database column. The call is a metadata lookup and does not move the record cursor.

Official terminal references​

Created 2026-07-15