com.webobjects.eocontrol
Interface EOValidation

All Superinterfaces:

NSValidation

All Known Subinterfaces:

EOEnterpriseObject

All Known Implementing Classes:

EOCustomObject

public interface EOValidation

extends NSValidation

The EOValidation interface in an extension of the NSValidation interface (which defines key-value based validation methods). EOValidation defines additional methods enterprise objects use to validate their values. The validation methods check for illegal value types, values outside of established limits, illegal relationships, and so on. EOCustomObject and EOGenericRecord provide default implementations of EOValidation, which are described in detail in this specification.

The Enterprise Objects Framework validates all of an object's properties before the object is saved to an external source -- either inserted or updated. Additionally, you can design your application so that changes to a property's value are validated immediately, as soon as a user attempts to leave an editable field in the user interface (Java Client applications only). Whenever an EODisplayGroup sets a value in an object, it sends the object a validateValueForKey message, allowing the object to coerce the value's type, perform any additional validation, and throw an exception if the value isn't valid. By default, the display group leaves validation errors to be handled when the object is saved, using validateValueForKey only for type coercion. However, you can use the EODisplayGroup method setValidatesChangesImmediately to tell the display group to immediately present an attention panel whenever a validation error is encountered.

Validating Before an Operation

The EOValidation methods -- validateForInsert, validateForUpdate, validateForSave, and validateForDelete -- validate an entire object to see if it's valid for a particular operation. These methods are invoked automatically by the Enterprise Objects Framework when the associated operation is initiated. EOCustomObject and EOGenericRecord provide default implementations, so you only have to implement them yourself when special validation logic is required. You can override these methods in your custom enterprise object classes to allow or refuse the operation based on property values. For example, a Fee object might refuse to be deleted if it hasn't been paid yet. Or you can override these methods to perform delayed validation of properties or to compare multiple properties against one another; for example, you might verify that a pair of dates is in the proper temporal order.

If you override any of these operation-specific validation methods, be sure to invoke the super implementation. This is important, as the default implementations of the validateFor... methods pass the check on to the object's EOClassDescription, which performs basic checking among properties, including invoking validateValueForKey for each property. The EOAccess layer's EOEntityClassDescription class verifies constraints based on an EOModel, such as delete rules. For example, the delete rule for a Department object might state that it can't be deleted if it still contains Employee objects.

The method validateForSave is the generic validation method for when an object is written to the external store. The default implementations of validateForInsert, validateForUpdate both invoke it. If an object performs validation that isn't specific to insertion or to updating, it should go in validateForSave.

Nested Class Summary

Nested classes inherited from class com.webobjects.foundation.NSValidation

NSValidation.DefaultImplementation, NSValidation.Utility, NSValidation.ValidationException

Method Summary

void	validateClientUpdate() Invoked after an object is being updated from a client application (Java Client) to validate whether the object is in an consistent state from the server-side perspective.
void	validateForDelete() Confirms that the receiver can be deleted in its current state, throwing an NSValidation.ValidationException if it can't.
void	validateForInsert() Confirms that the receiver can be inserted in its current state, throwing an NSValidation.ValidationException if it can't.
void	validateForSave() Confirms that the receiver can be saved in its current state, throwing an NSValidation.ValidationException if it can't.
void	validateForUpdate() Confirms that the receiver can be updated in its current state, throwing an NSValidation.ValidationException if it can't.

Methods inherited from interface com.webobjects.foundation.NSValidation

validateTakeValueForKeyPath, validateValueForKey

Method Detail

validateClientUpdate

public void validateClientUpdate()
                          throws NSValidation.ValidationException

Invoked after an object is being updated from a client application (Java Client) to validate whether the object is in an consistent state from the server-side perspective. EOCustomObject's implementation does nothing, and should be overridden if necessary.

Throws:

NSValidation.ValidationException

validateForDelete

public void validateForDelete()
                       throws NSValidation.ValidationException

Confirms that the receiver can be deleted in its current state, throwing an NSValidation.ValidationException if it can't. For example, an object can't be deleted if it has a relationship with a delete rule of EOClassDescription.DeleteRuleDeny and that relationship has a destination object.

EOCustomObject's implementation sends the receiver's EOClassDescription a message (which performs basic checking based on the presence or absence of values). Subclasses should invoke the super implementation before performing their own validation, and should combine any exception thrown by the super implementation with their own.

Throws:

NSValidation.ValidationException - when the delete request is invalid

NSValidation.ValidationException

See Also:

EOEnterpriseObject.propagateDeleteWithEditingContext(EOEditingContext)

validateForInsert

public void validateForInsert()
                       throws NSValidation.ValidationException

Confirms that the receiver can be inserted in its current state, throwing an NSValidation.ValidationException if it can't. EOCustomObject's implementation simply invokes validateForSave.

The method validateForSave is the generic validation method for when an object is written to the external store. If an object performs validation that isn't specific to insertion, it should go in validateForSave.

Throws:

NSValidation.ValidationException - when the insert request is invalid

NSValidation.ValidationException

See Also:

validateForSave()

validateForSave

public void validateForSave()
                     throws NSValidation.ValidationException

Confirms that the receiver can be saved in its current state, throwing an NSValidation.ValidationException if it can't. EOCustomObject's implementation sends the receiver's EOClassDescription a validateObjectForSave message, then iterates through all of the receiver's properties. If this results in more than one exception, the exception returned contains the additional ones in its userInfo dictionary under the NSValidation.ValidationException.AdditionalExceptionsKey. Subclasses should invoke the super implementation before performing their own validation, and should combine any exception thrown by the super implementation with their own.

Enterprise objects can implement this method to check that certain relations between properties hold. For example, that the end date of a vacation period follows the begin date. To validate an individual property, you can simply implement a method for it as described under NSValidation's validateValueForKey.

Throws:

NSValidation.ValidationException - when the save request is invalid

NSValidation.ValidationException

See Also:

NSValidation.validateValueForKey(Object, String)

validateForUpdate

public void validateForUpdate()
                       throws NSValidation.ValidationException

Confirms that the receiver can be updated in its current state, throwing an NSValidation.ValidationException if it can't. EOCustomObject's implementation simply invokes validateForSave.

The method validateForSave is the generic validation method for when an object is written to the external store. If an object performs validation that isn't specific to updating, it should go in validateForSave.

Throws:

NSValidation.ValidationException - when the update request is invalid

NSValidation.ValidationException

See Also:

validateForSave()