ftDataSet

ftDataSet = 29

Example

function IsNestedDataSet(Field: TField): Boolean;
begin
  Result := Field.DataType = ftDataSet;
end;

Usage

ftDataSet identifies a nested dataset field whose rows and child fields are owned and exposed by the parent provider.

Additional Technical Info

ftDataSet is ordinal 29 of TFieldType. Delphi maps it to TDataSetField, which exposes a NestedDataSet and child Fields under a structured parent value.

This is a nested rowset, not a connection or an independent top-level dataset. Its lifecycle, current row, editability and update propagation remain tied to the parent field/dataset. Do not free the nested dataset or retain it after the parent closes, scrolls or destroys its fields.

When mapping, define whether a Null parent, empty nested dataset and one row of Null children are distinct. Preserve row order only when the provider/schema defines it. Repeated navigation can trigger provider work; process each nested dataset in a bounded pass.

The example only inspects metadata and was source-reviewed; no nested dataset, database, runtime or image test ran.

External references

• Embarcadero TFieldType and TDataSetField.
• Free Pascal TFieldType compatibility reference; nested-dataset parity is not implied.

Created 2026-07-15