UpdateValueStrategy (Eclipse Platform API Specification)

java.lang.Object
- org.eclipse.core.databinding.UpdateValueStrategy

```
public class UpdateValueStrategy
extends Object
```
Customizes a Binding between two observable values. The following behaviors can be customized via the strategy:
- Validation
- Conversion
- Automatic processing
The update phases are:
1. Validate after get - validateAfterGet(Object)
2. Conversion - convert(Object)
3. Validate after conversion - validateAfterConvert(Object)
4. Validate before set - validateBeforeSet(Object)
5. Value set - doSet(IObservableValue, Object)
Validation:
Validators validate the value at multiple phases in the update process. Statuses returned from validators are aggregated into a MultiStatus until a status of ERROR or CANCEL is encountered. Either of these statuses will abort the update process. These statuses are available as the binding validation status.

Conversion:
A converter will convert the value from the type of the source observable into the type of the destination. The strategy has the ability to default converters for common scenarios.

Automatic processing:
The processing to perform when the source observable changes. This behavior is configured via policies provided on construction of the strategy (e.g. POLICY_NEVER, POLICY_CONVERT, POLICY_ON_REQUEST, POLICY_UPDATE).
Since:

1.0

See Also:

DataBindingContext.bindValue(IObservableValue, IObservableValue, UpdateValueStrategy, UpdateValueStrategy), ValidationStatusProvider.getValidationStatus(), IValidator, IConverter

Field Summary

Fields
Modifier and Type	Field and Description
`protected IValidator`	`afterConvertValidator`
`protected IValidator`	`afterGetValidator`
`protected IValidator`	`beforeSetValidator`
`protected IConverter`	`converter`
`static int`	`POLICY_CONVERT` Policy constant denoting that the source observable's state should be tracked, including validating changes except for `validateBeforeSet(Object)`, but that the destination observable's value should only be updated on request.
`static int`	`POLICY_NEVER` Policy constant denoting that the source observable's state should not be tracked and that the destination observable's value should never be updated.
`static int`	`POLICY_ON_REQUEST` Policy constant denoting that the source observable's state should not be tracked, but that validation, conversion and updating the destination observable's value should be performed when explicitly requested.
`static int`	`POLICY_UPDATE` Policy constant denoting that the source observable's state should be tracked, and that validation, conversion and updating the destination observable's value should be performed automatically on every change of the source observable value.
`protected boolean`	`provideDefaults`

Constructor Summary

Constructors
Constructor and Description
`UpdateValueStrategy()` Creates a new update value strategy for automatically updating the destination observable value whenever the source observable value changes.
`UpdateValueStrategy(boolean provideDefaults, int updatePolicy)` Creates a new update value strategy with a configurable update policy.
`UpdateValueStrategy(int updatePolicy)` Creates a new update value strategy with a configurable update policy.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`protected void`	`checkAssignable(Object toType, Object fromType, String errorString)`
`Object`	`convert(Object value)` Converts the value from the source type to the destination type.
`static UpdateValueStrategy`	`create(IConverter converter)` Create an `UpdateValueStrategy` with a converter
`protected IConverter`	`createConverter(Object fromType, Object toType)` Tries to create a converter that can convert from values of type fromType.
`protected IValidator`	`createValidator(Object fromType, Object toType)` Tries to create a validator that can validate values of type fromType.
`protected IStatus`	`doSet(IObservableValue observableValue, Object value)` Sets the current value of the given observable to the given value.
`protected void`	`fillDefaults(IObservableValue source, IObservableValue destination)` Fills out default values based upon the provided `source` and `destination`.
`int`	`getUpdatePolicy()`
`protected Boolean`	`isAssignableFromTo(Object fromType, Object toType)` Returns `Boolean.TRUE` if the from type is assignable to the to type, or `Boolean.FALSE` if it not, or `null` if unknown.
`protected IStatus`	`logErrorWhileSettingValue(Exception ex)`
`UpdateValueStrategy`	`setAfterConvertValidator(IValidator validator)` Sets the validator to be invoked after the source value is converted to the type of the destination observable.
`UpdateValueStrategy`	`setAfterGetValidator(IValidator validator)` Sets the validator to be invoked after the source value is retrieved at the beginning of the synchronization process.
`UpdateValueStrategy`	`setBeforeSetValidator(IValidator validator)` Sets the validator to be invoked before the value is to be set on the destination at the end of the synchronization process.
`UpdateValueStrategy`	`setConverter(IConverter converter)` Sets the converter to be invoked when converting from the source type to the destination type.
`IStatus`	`validateAfterConvert(Object value)` Validates the value after it is converted.
`IStatus`	`validateAfterGet(Object value)` Validates the value after it is retrieved from the source.
`IStatus`	`validateBeforeSet(Object value)` Validates the value before it is set on the destination.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - POLICY_NEVER
```
public static int POLICY_NEVER
```
    Policy constant denoting that the source observable's state should not be tracked and that the destination observable's value should never be updated.
  - POLICY_ON_REQUEST
```
public static int POLICY_ON_REQUEST
```
    Policy constant denoting that the source observable's state should not be tracked, but that validation, conversion and updating the destination observable's value should be performed when explicitly requested.
  - POLICY_CONVERT
```
public static int POLICY_CONVERT
```
    Policy constant denoting that the source observable's state should be tracked, including validating changes except for validateBeforeSet(Object), but that the destination observable's value should only be updated on request.
  - POLICY_UPDATE
```
public static int POLICY_UPDATE
```
    Policy constant denoting that the source observable's state should be tracked, and that validation, conversion and updating the destination observable's value should be performed automatically on every change of the source observable value.
  - afterGetValidator
```
protected IValidator afterGetValidator
```
  - afterConvertValidator
```
protected IValidator afterConvertValidator
```
  - beforeSetValidator
```
protected IValidator beforeSetValidator
```
  - provideDefaults
```
protected boolean provideDefaults
```
  - converter
```
protected IConverter converter
```
- Constructor Detail
  - UpdateValueStrategy
```
public UpdateValueStrategy()
```
    Creates a new update value strategy for automatically updating the destination observable value whenever the source observable value changes. Default validators and a default converter will be provided. The defaults can be changed by calling one of the setter methods.
  - UpdateValueStrategy
```
public UpdateValueStrategy(int updatePolicy)
```
    Creates a new update value strategy with a configurable update policy. Default validators and a default converter will be provided. The defaults can be changed by calling one of the setter methods.
    
    Parameters:
    
    updatePolicy - one of POLICY_NEVER, POLICY_ON_REQUEST, POLICY_CONVERT, or POLICY_UPDATE
  - UpdateValueStrategy
```
public UpdateValueStrategy(boolean provideDefaults,
                           int updatePolicy)
```
    Creates a new update value strategy with a configurable update policy. Default validators and a default converter will be provided if provideDefaults is true. The defaults can be changed by calling one of the setter methods.
    
    Parameters:
    
    provideDefaults - if true, default validators and a default converter will be provided based on the observable value's type.
    
    updatePolicy - one of POLICY_NEVER, POLICY_ON_REQUEST, POLICY_CONVERT, or POLICY_UPDATE
- Method Detail
  - createValidator
```
protected IValidator createValidator(Object fromType,
                                     Object toType)
```
    Tries to create a validator that can validate values of type fromType. Returns null if no validator could be created. Either toType or modelDescription can be null, but not both.
    
    Parameters:
    
    fromType -
    
    toType -
    
    Returns:
    
    an IValidator, or null if unsuccessful
  - fillDefaults
```
protected void fillDefaults(IObservableValue source,
                            IObservableValue destination)
```
    Fills out default values based upon the provided source and destination. If the strategy is to default values it will attempt to default a converter. If the converter can be defaulted an attempt is made to default the after get validator. If a validator cannot be defaulted it will be null.
    
    Parameters:
    
    source -
    
    destination -
  - getUpdatePolicy
```
public int getUpdatePolicy()
```
    Returns:
    
    the update policy
  - setAfterConvertValidator
```
public UpdateValueStrategy setAfterConvertValidator(IValidator validator)
```
    Sets the validator to be invoked after the source value is converted to the type of the destination observable.
    
    Parameters:
    
    validator -
    
    Returns:
    
    the receiver, to enable method call chaining
  - setAfterGetValidator
```
public UpdateValueStrategy setAfterGetValidator(IValidator validator)
```
    Sets the validator to be invoked after the source value is retrieved at the beginning of the synchronization process.
    
    Parameters:
    
    validator -
    
    Returns:
    
    the receiver, to enable method call chaining
  - setBeforeSetValidator
```
public UpdateValueStrategy setBeforeSetValidator(IValidator validator)
```
    Sets the validator to be invoked before the value is to be set on the destination at the end of the synchronization process.
    
    Parameters:
    
    validator -
    
    Returns:
    
    the receiver, to enable method call chaining
  - setConverter
```
public UpdateValueStrategy setConverter(IConverter converter)
```
    Sets the converter to be invoked when converting from the source type to the destination type.
    
    Parameters:
    
    converter -
    
    Returns:
    
    the receiver, to enable method call chaining
  - validateAfterConvert
```
public IStatus validateAfterConvert(Object value)
```
    Validates the value after it is converted.
    Default implementation will use the validator if one exists. If one does not exist no validation will occur.
    
    Parameters:
    
    value -
    
    Returns:
    
    an ok status
  - validateAfterGet
```
public IStatus validateAfterGet(Object value)
```
    Validates the value after it is retrieved from the source.
    Default implementation will use the validator if one exists. If one does not exist no validation will occur.
    
    Parameters:
    
    value -
    
    Returns:
    
    an ok status
  - validateBeforeSet
```
public IStatus validateBeforeSet(Object value)
```
    Validates the value before it is set on the destination.
    Default implementation will use the validator if one exists. If one does not exist no validation will occur.
    
    Parameters:
    
    value -
    
    Returns:
    
    an ok status
  - doSet
```
protected IStatus doSet(IObservableValue observableValue,
                        Object value)
```
    Sets the current value of the given observable to the given value. Clients may extend but must call the super implementation.
    
    Parameters:
    
    observableValue -
    
    value -
    
    Returns:
    
    status
  - create
```
public static UpdateValueStrategy create(IConverter converter)
```
    Create an UpdateValueStrategy with a converter
    
    Parameters:
    
    converter - the converter
    
    Returns:
    
    the update value strategy
    
    Since:
    
    1.6
  - checkAssignable
```
protected final void checkAssignable(Object toType,
                                     Object fromType,
                                     String errorString)
```
  - createConverter
```
protected IConverter createConverter(Object fromType,
                                     Object toType)
```
    Tries to create a converter that can convert from values of type fromType. Returns null if no converter could be created. Either toType or modelDescription can be null, but not both.
    
    Parameters:
    
    fromType -
    
    toType -
    
    Returns:
    
    an IConverter, or null if unsuccessful
  - isAssignableFromTo
```
protected Boolean isAssignableFromTo(Object fromType,
                                     Object toType)
```
    Returns Boolean.TRUE if the from type is assignable to the to type, or Boolean.FALSE if it not, or null if unknown.
    
    Parameters:
    
    fromType -
    
    toType -
    
    Returns:
    
    whether fromType is assignable to toType, or null if unknown
  - logErrorWhileSettingValue
```
protected IStatus logErrorWhileSettingValue(Exception ex)
```
    Parameters:
    
    ex - the exception, that was caught
    
    Returns:
    
    the validation status
  - convert
```
public Object convert(Object value)
```
    Converts the value from the source type to the destination type.
    Default implementation will use the setConverter(IConverter), if one exists. If no converter exists no conversion occurs.
    
    Parameters:
    
    value -
    
    Returns:
    
    the converted value

Class UpdateValueStrategy

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

POLICY_NEVER

POLICY_ON_REQUEST

POLICY_CONVERT

POLICY_UPDATE

afterGetValidator

afterConvertValidator

beforeSetValidator

provideDefaults

converter

Constructor Detail

UpdateValueStrategy

UpdateValueStrategy

UpdateValueStrategy

Method Detail

createValidator

fillDefaults

getUpdatePolicy

setAfterConvertValidator

setAfterGetValidator

setBeforeSetValidator

setConverter

validateAfterConvert

validateAfterGet

validateBeforeSet

doSet

create

checkAssignable

createConverter

isAssignableFromTo

logErrorWhileSettingValue

convert