[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] Reference for unit 'DB' (#fcl)

TFieldDefs

[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

Collection of TFieldDef instances.

Declaration

Source position: db.pas line 206

type TFieldDefs = class(TDefCollection)

public

  constructor Create();

  

Create a new instance of TFieldDefs

  function Add();

  

Add a new field definition to the collection.

  function AddFieldDef;

  

Add new TFieldDef

  procedure Assign(); overload;

  

Copy all items from one dataset to another

  function Find();

  

Find item by name

  procedure Update; overload;

  

Force update of definitions

  function MakeNameUnique(); virtual;

  

Create a unique field name starting from a base name

  property HiddenFields: Boolean; [rw]

  

Should field instances be created for hidden fields

  property Items []: TFieldDef; default; [rw]

  

Indexed access to the fielddef instances

end;

Inheritance

TFieldDefs

  

Collection of TFieldDef instances.

|

TDefCollection

  

Definition collection

|

TOwnedCollection

|

TCollection

|

TPersistent,IFPObserved

|

TObject

Description

TFieldDefs is used by each TDataset instance to keep a description of the data that it manages; for each field in a record that makes up the underlying data, the TFieldDefs instance keeps an instance of TFieldDef that describes the field's contents. For any internally calculated fields of the dataset, a TFieldDef instance is kept as well. This collection is filled by descendent classes of TDataset as soon as the dataset is opened; it is cleared when the dataset closes. After the collection was populated, the dataset creates TField instances based on all the definitions in the collections. If persistent fields were used, the contents of the fielddefs collection is compared to the field components that are present in the dataset. If the collection contains more field definitions than Field components, these extra fields will not be available in the dataset.

See also

TFieldDef

  

Class to describe one field in a record in a dataset

TDataset

  

Base class for records-based data-access


Documentation generated on: Jun 22 2020