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public interface IValidationDelegate
Interface used to track validation errors in forms and
form element component
s (including
org.apache.tapestry.form.AbstractTextField
and its subclasses).
In addition, controls how fields that are in error are presented (they can be decorated in various ways by the delegate; the default implementation adds two red asterisks to the right of the field).
Each Form
must have its own validation delegate instance.
Starting with release 1.0.8, this interface was extensively revised (in a non-backwards compatible way) to move the tracking of errors and invalid values (during a request cycle) to the delegate. It has evolved from a largely stateless conduit for error messages into a very stateful tracker of field state.
Starting with release 1.0.9, this interface was again reworked, to allow tracking of
errors in form components
, and to allow unassociated errors to be
tracked. Unassociated errors are "global", they don't apply to any particular field.
Fields vs. Form Element Components
For most simple forms, these terms are pretty much synonymous. Your form will render normally,
and each form element component will render only once. Some of your form components will be
ValidField
components and handle most of their validation internally (with the help
of IValidator
objects). In addition, your form listener may do additional
validation and notify the validation delegate of additional errors, some of which are associated
with a particular field, some of which are unassociated with any particular field.
But what happens if you use a Foreach
or
ListEdit
inside your form? Some of your components will
render multiple times. In this case you will have multiple fields. Each field will
have a unique field name (the
element id
, which you can
see this in the generated HTML). It is this field name that the delegate keys off of, which means
that some fields generated by a component may have errors and some may not, it all works fine
(with one exception).
The Exception
The problem is that a component doesn't know its field name until its render()
method is invoked (at which point, it allocates a unique field name from the
FormBehavior.getElementId(org.apache.tapestry.form.IFormComponent)
. This is
not a problem for the field or its IValidator
, but screws things up for the
FieldLabel
.
Typically, the label is rendered before the corresponding form component. Form
components leave their last assigned field name in their
name property
. So if the form component is in any kind of loop,
the FieldLabel
will key its name, display name
and error status off of its last renderred value. So the moral of the story is don't use
FieldLabel
in this situation.
Method Summary | |
---|---|
void |
clear()
Clears all tracking information. |
IFieldTracking |
getCurrentFieldTracking()
Returns the IFieldTracking for the current component, if any. |
java.util.List |
getErrorRenderers()
Returns a list of IRender objects, each of which will render on
error message for a field tracked by the delegate, plus any unassociated (with any field)
errors. |
java.lang.String |
getFieldInputValue()
Returns the string submitted by the client as the value for the current field. |
java.util.List |
getFieldTracking()
Returns a List of IFieldTracking , in default order (the order in which
fields are renderred). |
boolean |
getHasErrors()
Returns true if any form component has errors. |
boolean |
isInError()
Returns true if the current field is in error (that is, had bad input submitted by the end user). |
void |
record(IRender errorRenderer,
ValidationConstraint constraint)
Records an error in the current component, or an unassociated error. |
void |
record(java.lang.String message,
ValidationConstraint constraint)
Records an error in the current field, or an unassociated error if there is no current field. |
void |
record(ValidatorException ex)
The error notification method, invoked during the rewind phase (that is, while HTTP parameters are being extracted from the request and assigned to various object properties). |
void |
recordFieldInputValue(java.lang.String input)
Records the user's input for the current form component. |
void |
reset()
Resets any tracking information for the current field. |
void |
setFormComponent(IFormComponent component)
Invoked before other methods to configure the delegate for the given form component. |
void |
writeAttributes(IMarkupWriter writer,
IRequestCycle cycle,
IFormComponent component,
IValidator validator)
Invoked just before the <input> element is closed. |
void |
writeLabelPrefix(IFormComponent component,
IMarkupWriter writer,
IRequestCycle cycle)
Invoked by a FieldLabel just before writing the name of the form component. |
void |
writeLabelSuffix(IFormComponent component,
IMarkupWriter writer,
IRequestCycle cycle)
Invoked by a FieldLabel just after writing the name of the form component. |
void |
writePrefix(IMarkupWriter writer,
IRequestCycle cycle,
IFormComponent component,
IValidator validator)
Invoked before the field is rendered. |
void |
writeSuffix(IMarkupWriter writer,
IRequestCycle cycle,
IFormComponent component,
IValidator validator)
Invoked after the form component is rendered, so that the delegate may decorate the form component (if it is in error). |
Method Detail |
---|
void setFormComponent(IFormComponent component)
name
of the form component.
The caller should invoke this with a parameter of null to record unassociated global errors (errors not associated with any particular field).
boolean isInError()
java.lang.String getFieldInputValue()
java.util.List getFieldTracking()
List
of IFieldTracking
, in default order (the order in which
fields are renderred). A caller should not change the values (the List is immutable). May
return null if no fields are in error.
void reset()
void clear()
void recordFieldInputValue(java.lang.String input)
void record(ValidatorException ex)
Typically, the delegate simply invokes record(String, ValidationConstraint)
or
record(IRender, ValidationConstraint)
, but special delegates may override this
behavior to provide (in some cases) different error messages or more complicated error
renderers.
void record(java.lang.String message, ValidationConstraint constraint)
message
- message to display (@see RenderString}constraint
- the constraint that was violated, or null if not knownvoid record(IRender errorRenderer, ValidationConstraint constraint)
errorRenderer
- object that will render the error message (@see RenderString}constraint
- the constraint that was violated, or null if not knownvoid writePrefix(IMarkupWriter writer, IRequestCycle cycle, IFormComponent component, IValidator validator)
writer
- the writer to which output should be sentcycle
- the active request cyclecomponent
- the component being decoratedvalidator
- the validator for the component, or null if the component does have (or doesn't
support) a validatorvoid writeAttributes(IMarkupWriter writer, IRequestCycle cycle, IFormComponent component, IValidator validator)
writer
- the writer to which output should be sentcycle
- the active request cyclecomponent
- the component being decoratedvalidator
- the validator for the component, or null if the component does have (or doesn't
support) a validatorvoid writeSuffix(IMarkupWriter writer, IRequestCycle cycle, IFormComponent component, IValidator validator)
writer
- the writer to which output should be sentcycle
- the active request cyclecomponent
- the component being decoratedvalidator
- the validator for the component, or null if the component does have (or doesn't
support) a validatorvoid writeLabelPrefix(IFormComponent component, IMarkupWriter writer, IRequestCycle cycle)
FieldLabel
just before writing the name of the form component.
void writeLabelSuffix(IFormComponent component, IMarkupWriter writer, IRequestCycle cycle)
FieldLabel
just after writing the name of the form component.
boolean getHasErrors()
IFieldTracking getCurrentFieldTracking()
IFieldTracking
for the current component, if any. Useful when
displaying error messages for individual fields.
java.util.List getErrorRenderers()
IRender
objects, each of which will render on
error message for a field tracked by the delegate, plus any unassociated (with any field)
errors. These objects can be rendered or converted to a string (via toString()).
IRender
.
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