TcxValueType Class
Specifies the type of item values.
Declaration
TcxValueType = class(
TObject
)Remarks
TcxValueType represents the base class specifying the type of item values. Items are assigned particular types for the following purposes:
performing compare operations for this type value;
checking the validity of some value;
determining the size of data this type presents and getting/setting a value at a specific memory offset;
writing and reading a value to and from a stream.
There are value type classes inherited from TcxValueType that correspond to most of TField types:
| TField type | TcxValueType descendant |
|---|---|
| ftBCD | TcxCurrencyValueType |
| ftBoolean | TcxBooleanValueType |
| ftCurrency and ftFloat | TcxFloatValueType |
| ftDate, ftTime, and ftDateTime | TcxDateTimeValueType |
| ftFMTBcd | TcxFMTBcdValueType |
| ftInteger, ftAutoInc | TcxIntegerValueType |
| ftLargeint | TcxLargeIntValueType |
| ftSmallint | TcxSmallintValueType |
| ftString | TcxStringValueType |
| ftTimeStamp (corresponds to TSQLTimeStamp) | TcxSQLTimeStampValueType |
| ftWideString | TcxWideStringValueType |
| ftWord | TcxWordValueType |
| Other field types | TcxVariantValueType |
In bound mode, items are assigned types automatically according to the table listed above. In unbound and provider mode, you need to specify the item type explicitly by setting the item’s DataBinding.ValueTypeClass property. You should set DataBinding.ValueTypeClass to the class which matches the type of values an item stores. For graphical fields, you may use TcxStringValueType.
In unbound mode, ValueTypeClass specifies the default editor assigned to an item.
| ValueTypeClass | Default editor |
|---|---|
| TcxBooleanValueType | TcxCheckBox |
| TcxCurrencyValueType | TcxCurrencyEdit |
| TcxDateTimeValueType | TcxDateEdit |
| TcxFMTBcdValueType | TcxCurrencyEdit |
| TcxSQLTimeStampValueType | TcxDateEdit |
For items with ValueTypeClass set to another value, a simple text editor (TcxTextEdit) is used.
Note
The TcxObjectValueType class can be used to store a non-visual object that represents arbitrary data for an unbound item. It is not recommended that you use visual objects for this purpose, since this can raise exceptions when destroying the form that contains these objects.
In bound mode, the field type specifies the default editor. See the FieldName property topic for details.