TFieldDefs class

Declaration

Inheritance

1. TFieldDefs
2. TDefCollection
3. TOwnedCollection
4. TCollection
5. TPersistent
6. TObject

Descends from it: TSQLDBFieldDefs

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
• TDataset

Properties

HiddenFields	public	Should field instances be created for hidden fields.
Items	public	Indexed access to the fielddef instances.
ParentDef	public

Methods

FieldDefClass	protected
Create	public	Create a new instance of TFieldDefs.
Add	public	Add a new field definition to the collection.
AddFieldDef	public	Add new TFieldDef.
Assign	public	Copy all items from one dataset to another.
Find	public	Find item by name.
Update	public	Force update of definitions.
MakeNameUnique	public	Create a unique field name starting from a base name.

Inherited

From TDefCollection (5)

Dataset GetItemNames IndexOf SetItemName Updated

From TOwnedCollection (1)

GetOwner

From TCollection (25)

BeginUpdate Changed Clear Count Delete Destroy EndUpdate Exchange FindItemID GetAttr GetAttrCount GetEnumerator GetItem GetItemAttr GetNamePath Insert ItemClass Move Notify Owner PropName SetItem SetPropName Sort UpdateCount

From TPersistent (5)

AssignTo DefineProperties FPOAttachObserver FPODetachObserver FPONotifyObservers

From TObject (40)

AfterConstruction BeforeDestruction CheckDisposed ClassInfo ClassName ClassNameIs ClassParent ClassType CleanupInstance DefaultHandler DefaultHandlerStr Dispatch DispatchStr Disposed DisposeOf Equals FieldAddress Free FreeInstance GetDisposed GetHashCode GetInterface GetInterfaceByStr GetInterfaceEntry GetInterfaceEntryByStr GetInterfaceTable GetInterfaceWeak GetLastCastErrorInfo InheritsFrom InitInstance InstanceSize MethodAddress MethodName newinstance QualifiedClassName SafeCallException StringMessageTable SystemHasExtendedRTTI ToString UnitName