org.eclipse.core.databinding.validation
Class MultiValidator
java.lang.Object
org.eclipse.core.databinding.ValidationStatusProvider
org.eclipse.core.databinding.validation.MultiValidator
-
public abstract class MultiValidator
- extends
ValidationStatusProvider
A validator for cross-constraints between observables.
Some practical examples of cross-constraints:
- A start date cannot be later than an end date
- A list of percentages should add up to 100%
Example: require two integer fields to contain either both even or both odd
numbers.
DataBindingContext dbc = new DataBindingContext();
IObservableValue target0 = SWTObservables.observeText(text0, SWT.Modify);
IObservableValue target1 = SWTObservables.observeText(text1, SWT.Modify);
// Binding in two stages (from target to middle, then from middle to model)
// simplifies the validation logic. Using the middle observables saves
// the trouble of converting the target values (Strings) to the model type
// (integers) manually during validation.
final IObservableValue middle0 = new WritableValue(null, Integer.TYPE);
final IObservableValue middle1 = new WritableValue(null, Integer.TYPE);
dbc.bind(target0, middle0, null, null);
dbc.bind(target1, middle1, null, null);
// Create the multi-validator
MultiValidator validator = new MultiValidator() {
protected IStatus validate() {
// Calculate the validation status
Integer value0 = (Integer) middle0.getValue();
Integer value1 = (Integer) middle1.getValue();
if (Math.abs(value0.intValue()) % 2 != Math.abs(value1.intValue()) % 2)
return ValidationStatus
.error("Values must be both even or both odd");
return ValidationStatus.ok();
}
};
dbc.addValidationStatusProvider(validator);
// Bind the middle observables to the model observables.
IObservableValue model0 = new WritableValue(new Integer(2), Integer.TYPE);
IObservableValue model1 = new WritableValue(new Integer(4), Integer.TYPE);
dbc.bind(middle0, model0, null, null);
dbc.bind(middle1, model1, null, null);
MultiValidator can also prevent invalid data from being copied to model. This
is done by wrapping each target observable in a validated observable, and
then binding the validated observable to the model.
...
// Validated observables do not change value until the validator passes.
IObservableValue validated0 = validator.observeValidatedValue(middle0);
IObservableValue validated1 = validator.observeValidatedValue(middle1);
IObservableValue model0 = new WritableValue(new Integer(2), Integer.TYPE);
IObservableValue model1 = new WritableValue(new Integer(4), Integer.TYPE);
// Bind to the validated value, not the middle/target
dbc.bind(validated0, model0, null, null);
dbc.bind(validated1, model1, null, null);
Note: No guarantee is made as to the order of updates when multiple validated
observables change value at once (i.e. multiple updates pending when the
status becomes valid). Therefore the model may be in an invalid state after
the first but before the last pending update.
-
Since:
- 1.1
|
Constructor Summary
|
MultiValidator
()
Constructs a MultiValidator on the default realm. |
MultiValidator
(
Realm realm)
Constructs a MultiValidator on the given realm. |
|
Methods inherited from class java.lang.
Object
|
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
|
MultiValidator
public MultiValidator()
- Constructs a MultiValidator on the default realm.
MultiValidator
public MultiValidator(
Realm realm)
- Constructs a MultiValidator on the given realm.
-
Parameters:
-
realm - the realm on which validation takes place.
getValidationStatus
public
IObservableValue getValidationStatus()
- Returns an
IObservableValue whose value is always the current
validation status of this MultiValidator. The returned observable is in
the same realm as this MultiValidator.
-
-
Specified by:
-
getValidationStatus
in class
ValidationStatusProvider
-
-
Returns:
- an
IObservableValue whose value is always the current
validation status of this MultiValidator.
revalidate
protected final void revalidate()
- Signals that a re-evaluation of the current validation status is
necessary.
Clients may invoke this method whenever the validation status needs to be
updated due to some state change which cannot be automatically tracked by
the MultiValidator as it is not captured by any
IObservable
instance.
Note: There is no guarantee as of whether the MultiValidator will
immediately re-evaluate the validation status by calling
validate() when becoming dirty. Instead, it may decide to perform
the re-evaluation lazily.
-
-
Since:
- 1.2
-
See Also:
-
validate()
validate
protected abstract
IStatus validate()
- Returns the current validation status.
Note: To ensure that the validation status is kept current automatically,
all dependencies used to calculate status should be accessed through
IObservable instances. Each dependency observable must be in the
same realm as the MultiValidator. Other dependencies not captured by the
state of those observables may be accounted for by having clients
explicitly call
revalidate() whenever the validation
status needs to be re-evaluated due to some arbitrary change in the
application state.
-
-
Returns:
- the current validation status.
-
See Also:
-
revalidate()
observeValidatedValue
public
IObservableValue observeValidatedValue(
IObservableValue target)
- Returns a wrapper
IObservableValue which stays in sync with the
given target observable only when the validation status is valid.
Statuses of
OK,
INFO or
WARNING severity are considered valid.
The wrapper behaves as follows with respect to the validation status:
- While valid, the wrapper stays in sync with its target observable.
- While invalid, the wrapper's value is the target observable's last
valid value. If the target changes value, a stale event is fired
signaling that a change is pending.
- When status changes from invalid to valid, the wrapper takes the
value of the target observable, and synchronization resumes.
-
-
Parameters:
-
target - the target observable being wrapped. Must be in the same realm
as the MultiValidator.
-
Returns:
- an IObservableValue which stays in sync with the given target
observable only with the validation status is valid.
observeValidatedList
public
IObservableList observeValidatedList(
IObservableList target)
- Returns a wrapper
IObservableList which stays in sync with the
given target observable only when the validation status is valid.
Statuses of
OK,
INFO or
WARNING severity are considered valid.
The wrapper behaves as follows with respect to the validation status:
- While valid, the wrapper stays in sync with its target observable.
- While invalid, the wrapper's elements are the target observable's
last valid elements. If the target changes elements, a stale event is
fired signaling that a change is pending.
- When status changes from invalid to valid, the wrapper takes the
elements of the target observable, and synchronization resumes.
-
-
Parameters:
-
target - the target observable being wrapped. Must be in the same realm
as the MultiValidator.
-
Returns:
- an IObservableValue which stays in sync with the given target
observable only with the validation status is valid.
observeValidatedSet
public
IObservableSet observeValidatedSet(
IObservableSet target)
- Returns a wrapper
IObservableSet which stays in sync with the
given target observable only when the validation status is valid.
Statuses of
OK,
INFO or
WARNING severity are considered valid.
The wrapper behaves as follows with respect to the validation status:
- While valid, the wrapper stays in sync with its target observable.
- While invalid, the wrapper's elements are the target observable's
last valid elements. If the target changes elements, a stale event is
fired signaling that a change is pending.
- When status changes from invalid to valid, the wrapper takes the
elements of the target observable, and synchronization resumes.
-
-
Parameters:
-
target - the target observable being wrapped. Must be in the same realm
as the MultiValidator.
-
Returns:
- an IObservableValue which stays in sync with the given target
observable only with the validation status is valid.
observeValidatedMap
public
IObservableMap observeValidatedMap(
IObservableMap target)
- Returns a wrapper
IObservableMap which stays in sync with the
given target observable only when the validation status is valid.
Statuses of
OK,
INFO or
WARNING severity are considered valid.
The wrapper behaves as follows with respect to the validation status:
- While valid, the wrapper stays in sync with its target observable.
- While invalid, the wrapper's entries are the target observable's last
valid entries. If the target changes entries, a stale event is fired
signaling that a change is pending.
- When status changes from invalid to valid, the wrapper takes the
entries of the target observable, and synchronization resumes.
-
-
Parameters:
-
target - the target observable being wrapped. Must be in the same realm
as the MultiValidator.
-
Returns:
- an IObservableValue which stays in sync with the given target
observable only with the validation status is valid.
getTargets
public
IObservableList getTargets()
-
Description copied from class:
ValidationStatusProvider
- Returns an
IObservableList <
IObservable >
containing the target observables (if any) that are being tracked by this
validation status provider.
-
-
Specified by:
-
getTargets
in class
ValidationStatusProvider
-
-
Returns:
- an
IObservableList <
IObservable > (may be
empty)
getModels
public
IObservableList getModels()
-
Description copied from class:
ValidationStatusProvider
- Returns an
IObservableList <
IObservable >
containing the model observables (if any) that are being tracked by this
validation status provider.
-
-
Specified by:
-
getModels
in class
ValidationStatusProvider
-
-
Returns:
- an
IObservableList <
IObservable > (may be
empty)
dispose
public void dispose()
-
Description copied from class:
ValidationStatusProvider
- Disposes of this ValidationStatusProvider. Subclasses may extend, but
must call super.dispose().
-
-
Overrides:
-
dispose
in class
ValidationStatusProvider
-
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