TFieldDef¶

Class to describe one field in a record in a dataset.

Declaration¶

Source position: db.pas line 174

type

  TFieldDef = class(TNamedItem)
  public
    constructor Create(ACollection: TCollection);
    constructor Create(AOwner: TFieldDefs; const AName: string; 
                  ADataType: TFieldType; ASize: Integer; 
                  ARequired: Boolean; AFieldNo: LongInt; 
                  ACodePage: TSystemCodePage=CP_ACP); overload;
    destructor Destroy;
    function AddChild : TFieldDef;
    procedure Assign;
    function CreateField : TField;
    function HasChildDefs : Boolean;
    property FieldClass: TFieldClass; {r}
    property FieldNo: LongInt; {r}
    property CharSize: Word; {r}
    property InternalCalcField: Boolean; {rw}
    property ParentDef: TFieldDef; {r}
    property Required: Boolean; {rw}
    property Codepage: TSystemCodePage; {r}
  published
    property Attributes: TFieldAttributes; {rwd}
    property DataType: TFieldType; {rw}
    property ChildDefs: TFieldDefs; {rws}
    property Precision: LongInt; {rwd}
    property Size: Integer; {rwd}
  end;

Inheritance¶

Description¶

TFieldDef is used to describe the fields that are present in the data underlying the dataset. For each field in the underlying field, an TFieldDef instance is created when the dataset is opened. This class offers almost no methods, it is mainly a storage class, to store all relevant properties of fields in a record (name, data type, size, required or not, etc.)

Properties¶

Member	Visibility	Description
Attributes	published	Additional attributes of the field.
CharSize read only	public	Character size.
ChildDefs	published
Codepage read only	public	System code page for the values in string and wide string field types.
DataType	published	Data type for the field.
FieldClass read only	public	TField class used for this fielddef.
FieldNo read only	public	Field number.
InternalCalcField	public	Is this a definition of an internally calculated field ?
ParentDef read only	public
Precision	published	Precision used in BCD (Binary Coded Decimal) fields.
Required	public	Is the field required ?
Size	published	Size of the buffer needed to store the data of the field.

See all Properties

Methods¶

Member	Visibility	Description
AddChild	public
Assign	public	Assign the contents of one TFieldDef instance to another.
Create	public	Constructor for TFieldDef.
CreateField	public	Create TField instance based on definitions in current TFieldDef instance.
Destroy	public	Free the TFieldDef instance.
HasChildDefs	public

See all Methods

Name	Description
TDataset.FieldDefs	Definitions of available fields in the underlying database.
TFieldDefs	Collection of TFieldDef instances.