7.1.5 Data Binding - Reference Documentation
Authors: Graeme Rocher, Peter Ledbrook, Marc Palmer, Jeff Brown, Luke Daley, Burt Beckwith, Lari Hotari
Version: 3.0.12
7.1.5 Data Binding
Data binding is the act of "binding" incoming request parameters onto the properties of an object or an entire graph of objects. Data binding should deal with all necessary type conversion since request parameters, which are typically delivered by a form submission, are always strings whilst the properties of a Groovy or Java object may well not be.Map Based Binding
The data binder is capable of converting and assigning values in a Map to properties of an object. The binder will associate entries in the Map to properties of the object using the keys in the Map that have values which correspond to property names on the object. The following code demonstrates the basics:// grails-app/domain/Person.groovy class Person { String firstName String lastName Integer age }
def bindingMap = [firstName: 'Peter', lastName: 'Gabriel', age: 63]def person = new Person(bindingMap)assert person.firstName == 'Peter'
assert person.lastName == 'Gabriel'
assert person.age == 63
properties
property of the domain class:def bindingMap = [firstName: 'Peter', lastName: 'Gabriel', age: 63]def person = Person.get(someId) person.properties = bindingMapassert person.firstName == 'Peter' assert person.lastName == 'Gabriel' assert person.age == 63
class Person { String firstName String lastName Integer age Address homeAddress }class Address { String county String country }
def bindingMap = [firstName: 'Peter', lastName: 'Gabriel', age: 63, homeAddress: [county: 'Surrey', country: 'England'] ]def person = new Person(bindingMap)assert person.firstName == 'Peter'
assert person.lastName == 'Gabriel'
assert person.age == 63
assert person.homeAddress.county == 'Surrey'
assert person.homeAddress.country == 'England'
Binding To Collections And Maps
The data binder can populate and update Collections and Maps. The following code shows a simple example of populating aList
of objects in a domain class:class Band { String name static hasMany = [albums: Album] List albums }class Album { String title Integer numberOfTracks }
def bindingMap = [name: 'Genesis',
'albums[0]': [title: 'Foxtrot', numberOfTracks: 6],
'albums[1]': [title: 'Nursery Cryme', numberOfTracks: 7]]def band = new Band(bindingMap)assert band.name == 'Genesis'
assert band.albums.size() == 2
assert band.albums[0].title == 'Foxtrot'
assert band.albums[0].numberOfTracks == 6
assert band.albums[1].title == 'Nursery Cryme'
assert band.albums[1].numberOfTracks == 7
albums
were an array instead of a List
.Note that when binding to a Set
the structure of the Map
being bound to the Set
is the same as that of a Map
being bound to a List
but since a Set
is unordered, the indexes don't necessarily correspond to the order of elements in the Set
. In the code example above, if albums
were a Set
instead of a List
, the bindingMap
could look exactly the same but 'Foxtrot' might be the first album in the Set
or it might be the second. When updating existing elements in a Set
the Map
being assigned to the Set
must have id
elements in it which represent the element in the Set
being updated, as in the following example:/* * The value of the indexes 0 and 1 in albums[0] and albums[1] are arbitrary * values that can be anything as long as they are unique within the Map. * They do not correspond to the order of elements in albums because albums * is a Set. */ def bindingMap = ['albums[0]': [id: 9, title: 'The Lamb Lies Down On Broadway'] 'albums[1]': [id: 4, title: 'Selling England By The Pound']]def band = Band.get(someBandId)/* * This will find the Album in albums that has an id of 9 and will set its title * to 'The Lamb Lies Down On Broadway' and will find the Album in albums that has * an id of 4 and set its title to 'Selling England By The Pound'. In both * cases if the Album cannot be found in albums then the album will be retrieved * from the database by id, the Album will be added to albums and will be updated * with the values described above. If a Album with the specified id cannot be * found in the database, then a binding error will be created and associated * with the band object. More on binding errors later. */ band.properties = bindingMap
Map
the structure of the binding Map
is the same as the structure of a Map
used for binding to a List
or a Set
and the index inside of square brackets corresponds to the key in the Map
being bound to. See the following code:class Album { String title static hasMany = [players: Player] Map players }class Player { String name }
def bindingMap = [title: 'The Lamb Lies Down On Broadway',
'players[guitar]': [name: 'Steve Hackett'],
'players[vocals]': [name: 'Peter Gabriel'],
'players[keyboards]': [name: 'Tony Banks']]def album = new Album(bindingMap)assert album.title == 'The Lamb Lies Down On Broadway'
assert album.players.size() == 3
assert album.players.guitar.name == 'Steve Hackett'
assert album.players.vocals.name == 'Peter Gabriel'
assert album.players.keyboards.name == 'Tony Banks'
Map
, if the key specified in the binding Map
does not exist in the Map
being bound to then a new value will be created and added to the Map
with the specified key as in the following example:
def bindingMap = [title: 'The Lamb Lies Down On Broadway',
'players[guitar]': [name: 'Steve Hackett'],
'players[vocals]': [name: 'Peter Gabriel']
'players[keyboards]': [name: 'Tony Banks']]def album = new Album(bindingMap)assert album.title == 'The Lamb Lies Down On Broadway'
assert album.players.size() == 3
assert album.players.guitar == 'Steve Hackett'
assert album.players.vocals == 'Peter Gabriel'
assert album.players.keyboards == 'Tony Banks'def updatedBindingMap = ['players[drums]': [name: 'Phil Collins'],
'players[keyboards]': [name: 'Anthony George Banks']]album.properties = updatedBindingMapassert album.title == 'The Lamb Lies Down On Broadway'
assert album.players.size() == 4
assert album.players.guitar.name == 'Steve Hackett'
assert album.players.vocals.name == 'Peter Gabriel'
assert album.players.keyboards.name == 'Anthony George Banks'
assert album.players.drums.name == 'Phil Collins'
Binding Request Data to the Model
The params object that is available in a controller has special behavior that helps convert dotted request parameter names into nested Maps that the data binder can work with. For example, if a request includes request parameters namedperson.homeAddress.country
and person.homeAddress.city
with values 'USA' and 'St. Louis' respectively, params
would include entries like these:[person: [homeAddress: [country: 'USA', city: 'St. Louis']]]
def save() {
def b = new Book(params)
b.save()
}
new Book(params)
. By passing the params object to the domain class constructor Grails automatically recognizes that you are trying to bind from request parameters. So if we had an incoming request like:/book/save?title=The%20Stand&author=Stephen%20King
title
and author
request parameters would automatically be set on the domain class. You can use the properties property to perform data binding onto an existing instance:def save() { def b = Book.get(params.id) b.properties = params b.save() }
grails.databinding.trimStrings
property to false in grails-app/conf/application.groovy
.// the default value is true grails.databinding.trimStrings = false// ...
grails.databinding.convertEmptyStringsToNull
property to false in grials-app/conf/application.groovy
.// the default value is true grails.databinding.convertEmptyStringsToNull = false// ...
trimStrings
is true
and convertEmptyStringsToNull
is true
, not only will empty Strings be converted to null but also blank Strings. A blank String is any String such that the trim()
method returns an empty String.These forms of data binding in Grails are very convenient, but also indiscriminate. In other words, they will bind all non-transient, typed instance properties of the target object, including ones that you may not want bound. Just because the form in your UI doesn't submit all the properties, an attacker can still send malign data via a raw HTTP request. Fortunately, Grails also makes it easy to protect against such attacks - see the section titled "Data Binding and Security concerns" for more information.
Data binding and Single-ended Associations
If you have aone-to-one
or many-to-one
association you can use Grails' data binding capability to update these relationships too. For example if you have an incoming request such as:/book/save?author.id=20
.id
suffix on the request parameter and look up the Author
instance for the given id when doing data binding such as:def b = new Book(params)
null
by passing the literal String
"null". For example:/book/save?author.id=null
Data Binding and Many-ended Associations
If you have a one-to-many or many-to-many association there are different techniques for data binding depending of the association type.If you have aSet
based association (the default for a hasMany
) then the simplest way to populate an association is to send a list of identifiers. For example consider the usage of <g:select>
below:<g:select name="books"
from="${Book.list()}"
size="5" multiple="yes" optionKey="id"
value="${author?.books}" />
books
association.However, if you have a scenario where you want to update the properties of the associated objects the this technique won't work. Instead you use the subscript operator:<g:textField name="books[0].title" value="the Stand" /> <g:textField name="books[1].title" value="the Shining" />
Set
based association it is critical that you render the mark-up in the same order that you plan to do the update in. This is because a Set
has no concept of order, so although we're referring to books0
and books1
it is not guaranteed that the order of the association will be correct on the server side unless you apply some explicit sorting yourself.This is not a problem if you use List
based associations, since a List
has a defined order and an index you can refer to. This is also true of Map
based associations.Note also that if the association you are binding to has a size of two and you refer to an element that is outside the size of association:<g:textField name="books[0].title" value="the Stand" /> <g:textField name="books[1].title" value="the Shining" /> <g:textField name="books[2].title" value="Red Madder" />
List
using the same .id
syntax as you would use with a single-ended association. For example:<g:select name="books[0].id" from="${bookList}" value="${author?.books[0]?.id}" /><g:select name="books[1].id" from="${bookList}" value="${author?.books[1]?.id}" /><g:select name="books[2].id" from="${bookList}" value="${author?.books[2]?.id}" />
books List
to be selected separately.Entries at particular indexes can be removed in the same way too. For example:<g:select name="books[0].id"
from="${Book.list()}"
value="${author?.books[0]?.id}"
noSelection="['null': '']"/>
books0
if the empty option is chosen.Binding to a Map
property works the same way except that the list index in the parameter name is replaced by the map key:<g:select name="images[cover].id"
from="${Image.list()}"
value="${book?.images[cover]?.id}"
noSelection="['null': '']"/>
Map
property images
under a key of "cover"
.When binding to Maps, Arrays and Collections the data binder will automatically grow the size of the collections as necessary.The default limit to how large the binder will grow a collection is 256. If the data binder encounters an entry that requires the collection be grown beyond that limit, the entry is ignored. The limit may be configured by assigning a value to thegrails.databinding.autoGrowCollectionLimit
property inapplication.groovy
.
// grails-app/conf/application.groovy// the default value is 256
grails.databinding.autoGrowCollectionLimit = 128// ...
Data binding with Multiple domain classes
It is possible to bind data to multiple domain objects from the params object.For example so you have an incoming request to:/book/save?book.title=The%20Stand&author.name=Stephen%20King
author.
or book.
which is used to isolate which parameters belong to which type. Grails' params
object is like a multi-dimensional hash and you can index into it to isolate only a subset of the parameters to bind.def b = new Book(params.book)
book.title
parameter to isolate only parameters below this level to bind. We could do the same with an Author
domain class:def a = new Author(params.author)
Data Binding and Action Arguments
Controller action arguments are subject to request parameter data binding. There are 2 categories of controller action arguments. The first category is command objects. Complex types are treated as command objects. See the Command Objects section of the user guide for details. The other category is basic object types. Supported types are the 8 primitives, their corresponding type wrappers and java.lang.String. The default behavior is to map request parameters to action arguments by name:class AccountingController { // accountNumber will be initialized with the value of params.accountNumber // accountType will be initialized with params.accountType def displayInvoice(String accountNumber, int accountType) { // … } }
params.accountType
request parameter has to be converted to an int
. If type conversion fails for any reason, the argument will have its default value per normal Java behavior (null for type wrapper references, false for booleans and zero for numbers) and a corresponding error will be added to the errors
property of the defining controller./accounting/displayInvoice?accountNumber=B59786&accountType=bogusValue
errors.hasErrors()
will be true, the controller's errors.errorCount
will be equal to 1 and the controller's errors.getFieldError('accountType')
will contain the corresponding error.If the argument name does not match the name of the request parameter then the @grails.web.RequestParameter
annotation may be applied to an argument to express the name of the request parameter which should be bound to that argument:import grails.web.RequestParameterclass AccountingController { // mainAccountNumber will be initialized with the value of params.accountNumber // accountType will be initialized with params.accountType def displayInvoice(@RequestParameter('accountNumber') String mainAccountNumber, int accountType) { // … } }
Data binding and type conversion errors
Sometimes when performing data binding it is not possible to convert a particular String into a particular target type. This results in a type conversion error. Grails will retain type conversion errors inside the errors property of a Grails domain class. For example:class Book { … URL publisherURL }
Book
that uses the java.net.URL
class to represent URLs. Given an incoming request such as:/book/save?publisherURL=a-bad-url
a-bad-url
to the publisherURL
property as a type mismatch error occurs. You can check for these like this:def b = new Book(params)if (b.hasErrors()) { println "The value ${b.errors.getFieldError('publisherURL').rejectedValue}" + " is not a valid URL!" }
grails-app/i18n/messages.properties
file to use for the error. You can use a generic error message handler such as:typeMismatch.java.net.URL=The field {0} is not a valid URL
typeMismatch.Book.publisherURL=The publisher URL you specified is not a valid URL
The BindUsing Annotation
The BindUsing annotation may be used to define a custom binding mechanism for a particular field in a class. Any time data binding is being applied to the field the closure value of the annotation will be invoked with 2 arguments. The first argument is the object that data binding is being applied to and the second argument is DataBindingSource which is the data source for the data binding. The value returned from the closure will be bound to the property. The following example would result in the upper case version of thename
value in the source being applied to the name
field during data binding.import org.grails.databinding.BindUsingclass SomeClass { @BindUsing({obj, source -> //source is DataSourceBinding which is similar to a Map //and defines getAt operation but source.name cannot be used here. //In order to get name from source use getAt instead as shown below. source['name']?.toUpperCase() }) String name }
Note that data binding is only possible when the name of the request parameter matches with the field name in the class. Here,The BindUsing annotation may be used to define a custom binding mechanism for all of the fields on a particular class. When the annotation is applied to a class, the value assigned to the annotation should be a class which implements the BindingHelper interface. An instance of that class will be used any time a value is bound to a property in the class that this annotation has been applied to.name
from request parameters matches withname
fromSomeClass
.
@BindUsing(SomeClassWhichImplementsBindingHelper) class SomeClass { String someProperty Integer someOtherProperty }
Custom Data Converters
The binder will do a lot of type conversion automatically. Some applications may want to define their own mechanism for converting values and a simple way to do this is to write a class which implements ValueConverter and register an instance of that class as a bean in the Spring application context.package com.myapp.convertersimport org.grails.databinding.converters.ValueConverter/** * A custom converter which will convert String of the * form 'city:state' into an Address object. */ class AddressValueConverter implements ValueConverter { boolean canConvert(value) { value instanceof String } def convert(value) { def pieces = value.split(':') new com.myapp.Address(city: pieces[0], state: pieces[1]) } Class<?> getTargetType() { com.myapp.Address } }
// grails-app/conf/spring/resources.groovybeans = { addressConverter com.myapp.converters.AddressValueConverter // ...}
class Person { String firstName Address homeAddress }class Address { String city String state }def person = new Person() person.properties = [firstName: 'Jeff', homeAddress: "O'Fallon:Missouri"] assert person.firstName == 'Jeff' assert person.homeAddress.city = "O'Fallon" assert person.homeAddress.state = 'Missouri'
Date Formats For Data Binding
A custom date format may be specified to be used when binding a String to a Date value by applying the BindingFormat annotation to a Date field.import org.grails.databinding.BindingFormatclass Person {
@BindingFormat('MMddyyyy')
Date birthDate
}
application.groovy
to define date formats which will be used application wide when binding to Date.// grails-app/conf/application.groovygrails.databinding.dateFormats = ['MMddyyyy', 'yyyy-MM-dd HH:mm:ss.S', "yyyy-MM-dd'T'hh:mm:ss'Z'"]
grails.databinding.dateFormats
will be attempted in the order in which they are included in the List. If a property is marked with @BindingFormat, the @BindingFormat will take precedence over the values specified in grails.databinding.dateFormats
.The default formats that are used are "yyyy-MM-dd HH:mm:ss.S", "yyyy-MM-dd'T'hh:mm:ss'Z'" and "yyyy-MM-dd HH:mm:ss.S z".Custom Formatted Converters
You may supply your own handler for the BindingFormat annotation by writing a class which implements the FormattedValueConverter interface and registering an instance of that class as a bean in the Spring application context. Below is an example of a trivial custom String formatter that might convert the case of a String based on the value assigned to the BindingFormat annotation.package com.myapp.convertersimport org.grails.databinding.converters.FormattedValueConverterclass FormattedStringValueConverter implements FormattedValueConverter { def convert(value, String format) { if('UPPERCASE' == format) { value = value.toUpperCase() } else if('LOWERCASE' == format) { value = value.toLowerCase() } value } Class getTargetType() { // specifies the type to which this converter may be applied String } }
// grails-app/conf/spring/resources.groovybeans = { formattedStringConverter com.myapp.converters.FormattedStringValueConverter // ...}
BindingFormat
annotation may be applied to String fields to inform the data binder to take advantage of the custom converter.import org.grails.databinding.BindingFormatclass Person { @BindingFormat('UPPERCASE') String someUpperCaseString @BindingFormat('LOWERCASE') String someLowerCaseString String someOtherString }
Localized Binding Formats
TheBindingFormat
annotation supports localized format strings by using the optional code
attribute. If a value is assigned to the code attribute that value will be used as the message code to retrieve the binding format string from the messageSource
bean in the Spring application context and that lookup will be localized.import org.grails.databinding.BindingFormatclass Person {
@BindingFormat(code='date.formats.birthdays')
Date birthDate
}
# grails-app/conf/i18n/messages.properties date.formats.birthdays=MMddyyyy
# grails-app/conf/i18n/messages_es.properties date.formats.birthdays=ddMMyyyy
Structured Data Binding Editors
A structured data binding editor is a helper class which can bind structured request parameters to a property. The common use case for structured binding is binding to aDate
object which might be constructed from several smaller pieces of information contained in several request parameters with names like birthday_month
, birthday_date
and birthday_year
. The structured editor would retrieve all of those individual pieces of information and use them to construct a Date
.The framework provides a structured editor for binding to Date
objects. An application may register its own structured editors for whatever types are appropriate. Consider the following classes:// src/groovy/databinding/Gadget.groovy
package databindingclass Gadget {
Shape expandedShape
Shape compressedShape
}
// src/groovy/databinding/Shape.groovy package databindingclass Shape { int area }
Gadget
has 2 Shape
fields. A Shape
has an area
property. It may be that the application wants to accept request parameters like width
and height
and use those to calculate the area
of a Shape
at binding time. A structured binding editor is well suited for that.The way to register a structured editor with the data binding process is to add an instance of the org.grails.databinding.TypedStructuredBindingEditor interface to the Spring application context. The easiest way to implement the TypedStructuredBindingEditor
interface is to extend the org.grails.databinding.converters.AbstractStructuredBindingEditor abstract class and override the getPropertyValue
method as shown below:// src/groovy/databinding/converters/StructuredShapeEditor.groovy package databinding.convertersimport databinding.Shapeimport org.grails.databinding.converters.AbstractStructuredBindingEditorclass StructuredShapeEditor extends AbstractStructuredBindingEditor<Shape> { public Shape getPropertyValue(Map values) { // retrieve the individual values from the Map def width = values.width as int def height = values.height as int // use the values to calculate the area of the Shape def area = width * height // create and return a Shape with the appropriate area new Shape(area: area) } }
// grails-app/conf/spring/resources.groovy beans = { shapeEditor databinding.converters.StructuredShapeEditor // … }
Gadget
class it will check to see if there are request parameters with names compressedShape
and expandedShape
which have a value of "struct" and if they do exist, that will trigger the use of the StructuredShapeEditor
. The individual components of the structure need to have parameter names of the form propertyName_structuredElementName. In the case of the Gadget
class above that would mean that the compressedShape
request parameter should have a value of "struct" and the compressedShape_width
and compressedShape_height
parameters should have values which represent the width and the height of the compressed Shape
. Similarly, the expandedShape
request parameter should have a value of "struct" and the expandedShape_width
and expandedShape_height
parameters should have values which represent the width and the height of the expanded Shape
.// grails-app/controllers/demo/DemoController.groovy class DemoController { def createGadget(Gadget gadget) { /* /demo/createGadget?expandedShape=struct&expandedShape_width=80&expandedShape_height=30 &compressedShape=struct&compressedShape_width=10&compressedShape_height=3 */ // with the request parameters shown above gadget.expandedShape.area would be 2400 // and gadget.compressedShape.area would be 30 // ... } }
Data Binding Event Listeners
The DataBindingListener interface provides a mechanism for listeners to be notified of data binding events. The interface looks like this:package org.grails.databinding.events;import org.grails.databinding.errors.BindingError;public interface DataBindingListener { /** * @return true if the listener is interested in events for the specified type. */ boolean supports(Class<?> clazz); /** * Called when data binding is about to start. * * @param target The object data binding is being imposed upon * @param errors the Spring Errors instance (a org.springframework.validation.BindingResult) * @return true if data binding should continue */ Boolean beforeBinding(Object target, Object errors); /** * Called when data binding is about to imposed on a property * * @param target The object data binding is being imposed upon * @param propertyName The name of the property being bound to * @param value The value of the property being bound * @param errors the Spring Errors instance (a org.springframework.validation.BindingResult) * @return true if data binding should continue, otherwise return false */ Boolean beforeBinding(Object target, String propertyName, Object value, Object errors); /** * Called after data binding has been imposed on a property * * @param target The object data binding is being imposed upon * @param propertyName The name of the property that was bound to * @param errors the Spring Errors instance (a org.springframework.validation.BindingResult) */ void afterBinding(Object target, String propertyName, Object errors); /** * Called after data binding has finished. * * @param target The object data binding is being imposed upon * @param errors the Spring Errors instance (a org.springframework.validation.BindingResult) */ void afterBinding(Object target, Object errors); /** * Called when an error occurs binding to a property * @param error encapsulates information about the binding error * @param errors the Spring Errors instance (a org.springframework.validation.BindingResult) * @see BindingError */ void bindingError(BindingError error, Object errors); }
DataBindingListener
interface and provides default implementations for all of the methods in the interface so this class is well suited for subclassing so your listener class only needs to provide implementations for the methods your listener is interested in.The Grails data binder has limited support for the older BindEventListener style listeners. BindEventListener
looks like this:package org.codehaus.groovy.grails.web.binding;import org.springframework.beans.MutablePropertyValues; import org.springframework.beans.TypeConverter;public interface BindEventListener { /** * @param target The target to bind to * @param source The source of the binding, typically a Map * @param typeConverter The type converter to be used */ void doBind(Object target, MutablePropertyValues source, TypeConverter typeConverter); }
BindEventListener
is disabled by default. To enable support assign a value of true
to the grails.databinding.enableSpringEventAdapter
property in grails-app/conf/application.groovy
.// grails-app/conf/application.groovy
grails.databinding.enableSpringEventAdapter=true...
enableSpringEventAdapter
set to true
instances of BindEventListener
which are in the Spring application context will automatically be registered with the data binder. Notice that the MutablePropertyValues
and TypeConverter
arguments to the doBind
method in BindEventListener
are Spring specific classes and are not relevant to the current data binder. The event adapter will pass null
values for those arguments. The only real value passed into the doBind
method will be the object being bound to. This limited support is provided for backward compatibility and will be useful for a subset of scenarios. Developers are encouraged to migrate their BindEventListener
beans to the newer DataBindingListener
model.Using The Data Binder Directly
There are situations where an application may want to use the data binder directly. For example, to do binding in a Service on some arbitrary object which is not a domain class. The following will not work because theproperties
property is read only.// src/groovy/bindingdemo/Widget.groovy package bindingdemoclass Widget { String name Integer size }
// grails-app/services/bindingdemo/WidgetService.groovy package bindingdemoclass WidgetService { def updateWidget(Widget widget, Map data) { // this will throw an exception because // properties is read-only widget.properties = data } }
grailsWebDataBinder
. That bean implements the DataBinder interface. The following code demonstrates using the data binder directly.// grails-app/services/bindingdmeo/WidgetService package bindingdemoimport org.grails.databinding.SimpleMapDataBindingSourceclass WidgetService { // this bean will be autowired into the service def grailsWebDataBinder def updateWidget(Widget widget, Map data) { grailsWebDataBinder.bind widget, data as SimpleMapDataBindingSource }}
bind
method.Data Binding and Security Concerns
When batch updating properties from request parameters you need to be careful not to allow clients to bind malicious data to domain classes and be persisted in the database. You can limit what properties are bound to a given domain class using the subscript operator:def p = Person.get(1)p.properties['firstName','lastName'] = params
firstName
and lastName
properties will be bound.Another way to do this is is to use Command Objects as the target of data binding instead of domain classes. Alternatively there is also the flexible bindData method.The bindData
method allows the same data binding capability, but to arbitrary objects:def p = new Person()
bindData(p, params)
bindData
method also lets you exclude certain parameters that you don't want updated:def p = new Person()
bindData(p, params, [exclude: 'dateOfBirth'])
def p = new Person()
bindData(p, params, [include: ['firstName', 'lastName']])
Note that if an empty List is provided as a value for the include
parameter then all fields will be subject to binding if they are not explicitly excluded.