public class

DataBinder

extends Object
implements PropertyEditorRegistry TypeConverter
java.lang.Object
   ↳ org.springframework.validation.DataBinder
Known Direct Subclasses
Known Indirect Subclasses

Class Overview

Binder that allows for setting property values onto a target object, including support for validation and binding result analysis. The binding process can be customized through specifying allowed fields, required fields, custom editors, etc.

Note that there are potential security implications in failing to set an array of allowed fields. In the case of HTTP form POST data for example, malicious clients can attempt to subvert an application by supplying values for fields or properties that do not exist on the form. In some cases this could lead to illegal data being set on command objects or their nested objects. For this reason, it is highly recommended to specify the allowedFields property on the DataBinder.

The binding results can be examined via the BindingResult interface, extending the Errors interface: see the getBindingResult() method. Missing fields and property access exceptions will be converted to FieldErrors, collected in the Errors instance, using the following error codes:

  • Missing field error: "required"
  • Type mismatch error: "typeMismatch"
  • Method invocation error: "methodInvocation"

By default, binding errors get resolved through the BindingErrorProcessor strategy, processing for missing fields and property access exceptions: see the setBindingErrorProcessor(BindingErrorProcessor) method. You can override the default strategy if needed, for example to generate different error codes.

Custom validation errors can be added afterwards. You will typically want to resolve such error codes into proper user-visible error messages; this can be achieved through resolving each error via a MessageSource, which is able to resolve an ObjectError/FieldError through its getMessage(org.springframework.context.MessageSourceResolvable, java.util.Locale) method. The list of message codes can be customized through the MessageCodesResolver strategy: see the setMessageCodesResolver(MessageCodesResolver) method. DefaultMessageCodesResolver's javadoc states details on the default resolution rules.

This generic data binder can be used in any kind of environment. It is typically used by Spring web MVC controllers, via the web-specific subclasses ServletRequestDataBinder and PortletRequestDataBinder.

Summary

Constants
String DEFAULT_OBJECT_NAME Default object name used for binding: "target"
Fields
protected static final Log logger We'll create a lot of DataBinder instances: Let's use a static logger.
Public Constructors
DataBinder(Object target)
Create a new DataBinder instance, with default object name.
DataBinder(Object target, String objectName)
Create a new DataBinder instance.
Public Methods
void bind(PropertyValues pvs)
Bind the given property values to this binder's target.
Map close()
Close this DataBinder, which may result in throwing a BindException if it encountered any errors.
<T> T convertIfNecessary(Object value, Class<T> requiredType)
Convert the value to the required type (if necessary from a String).
<T> T convertIfNecessary(Object value, Class<T> requiredType, MethodParameter methodParam)
Convert the value to the required type (if necessary from a String).
PropertyEditor findCustomEditor(Class requiredType, String propertyPath)
Find a custom property editor for the given type and property.
String[] getAllowedFields()
Return the fields that should be allowed for binding.
BindingErrorProcessor getBindingErrorProcessor()
Return the strategy for processing binding errors.
BindingResult getBindingResult()
Return the BindingResult instance created by this DataBinder.
ConversionService getConversionService()
Return the associated ConversionService, if any.
String[] getDisallowedFields()
Return the fields that should not be allowed for binding.
BindException getErrors()
This method is deprecated. in favor of getBindingResult(). Use the BindException(BindingResult) constructor to create a BindException instance if still needed.
String getObjectName()
Return the name of the bound object.
String[] getRequiredFields()
Return the fields that are required for each binding process.
Object getTarget()
Return the wrapped target object.
Validator getValidator()
Return the Validator to apply after each binding step, if any.
void initBeanPropertyAccess()
Initialize standard JavaBean property access for this DataBinder.
void initDirectFieldAccess()
Initialize direct field access for this DataBinder, as alternative to the default bean property access.
boolean isAutoGrowNestedPaths()
Return whether "auto-growing" of nested paths has been activated.
boolean isIgnoreInvalidFields()
Return whether to ignore invalid fields when binding.
boolean isIgnoreUnknownFields()
Return whether to ignore unknown fields when binding.
void registerCustomEditor(Class requiredType, String field, PropertyEditor propertyEditor)
Register the given custom property editor for the given type and property, or for all properties of the given type.
void registerCustomEditor(Class requiredType, PropertyEditor propertyEditor)
Register the given custom property editor for all properties of the given type.
void setAllowedFields(String... allowedFields)
Register fields that should be allowed for binding.
void setAutoGrowNestedPaths(boolean autoGrowNestedPaths)
Set whether this binder should attempt to "auto-grow" a nested path that contains a null value.
void setBindingErrorProcessor(BindingErrorProcessor bindingErrorProcessor)
Set the strategy to use for processing binding errors, that is, required field errors and PropertyAccessExceptions.
void setConversionService(ConversionService conversionService)
Specify a Spring 3.0 ConversionService to use for converting property values, as an alternative to JavaBeans PropertyEditors.
void setDisallowedFields(String... disallowedFields)
Register fields that should not be allowed for binding.
void setExtractOldValueForEditor(boolean extractOldValueForEditor)
Set whether to extract the old field value when applying a property editor to a new value for a field.
void setIgnoreInvalidFields(boolean ignoreInvalidFields)
Set whether to ignore invalid fields, that is, whether to ignore bind parameters that have corresponding fields in the target object which are not accessible (for example because of null values in the nested path).
void setIgnoreUnknownFields(boolean ignoreUnknownFields)
Set whether to ignore unknown fields, that is, whether to ignore bind parameters that do not have corresponding fields in the target object.
void setMessageCodesResolver(MessageCodesResolver messageCodesResolver)
Set the strategy to use for resolving errors into message codes.
void setRequiredFields(String... requiredFields)
Register fields that are required for each binding process.
void setValidator(Validator validator)
Set the Validator to apply after each binding step.
void validate()
Invoke the specified Validator, if any.
Protected Methods
void applyPropertyValues(MutablePropertyValues mpvs)
Apply given property values to the target object.
void checkAllowedFields(MutablePropertyValues mpvs)
Check the given property values against the allowed fields, removing values for fields that are not allowed.
void checkRequiredFields(MutablePropertyValues mpvs)
Check the given property values against the required fields, generating missing field errors where appropriate.
void doBind(MutablePropertyValues mpvs)
Actual implementation of the binding process, working with the passed-in MutablePropertyValues instance.
AbstractPropertyBindingResult getInternalBindingResult()
Return the internal BindingResult held by this DataBinder, as AbstractPropertyBindingResult.
ConfigurablePropertyAccessor getPropertyAccessor()
Return the underlying PropertyAccessor of this binder's BindingResult.
PropertyEditorRegistry getPropertyEditorRegistry()
Return the underlying TypeConverter of this binder's BindingResult.
SimpleTypeConverter getSimpleTypeConverter()
Return this binder's underlying SimpleTypeConverter.
TypeConverter getTypeConverter()
Return the underlying TypeConverter of this binder's BindingResult.
boolean isAllowed(String field)
Return if the given field is allowed for binding.
[Expand]
Inherited Methods
From class java.lang.Object
From interface org.springframework.beans.PropertyEditorRegistry
From interface org.springframework.beans.TypeConverter

Constants

public static final String DEFAULT_OBJECT_NAME

Default object name used for binding: "target"

Constant Value: "target"

Fields

protected static final Log logger

We'll create a lot of DataBinder instances: Let's use a static logger.

Public Constructors

public DataBinder (Object target)

Create a new DataBinder instance, with default object name.

Parameters
target the target object to bind onto (or null if the binder is just used to convert a plain parameter value)

public DataBinder (Object target, String objectName)

Create a new DataBinder instance.

Parameters
target the target object to bind onto (or null if the binder is just used to convert a plain parameter value)
objectName the name of the target object

Public Methods

public void bind (PropertyValues pvs)

Bind the given property values to this binder's target.

This call can create field errors, representing basic binding errors like a required field (code "required"), or type mismatch between value and bean property (code "typeMismatch").

Note that the given PropertyValues should be a throwaway instance: For efficiency, it will be modified to just contain allowed fields if it implements the MutablePropertyValues interface; else, an internal mutable copy will be created for this purpose. Pass in a copy of the PropertyValues if you want your original instance to stay unmodified in any case.

Parameters
pvs property values to bind

public Map close ()

Close this DataBinder, which may result in throwing a BindException if it encountered any errors.

Returns
  • the model Map, containing target object and Errors instance
Throws
BindException if there were any errors in the bind operation
See Also

public T convertIfNecessary (Object value, Class<T> requiredType)

Convert the value to the required type (if necessary from a String).

Conversions from String to any type will typically use the setAsText method of the PropertyEditor class. Note that a PropertyEditor must be registered for the given class for this to work; this is a standard JavaBeans API. A number of PropertyEditors are automatically registered.

Parameters
value the value to convert
requiredType the type we must convert to (or null if not known, for example in case of a collection element)
Returns
  • the new value, possibly the result of type conversion

public T convertIfNecessary (Object value, Class<T> requiredType, MethodParameter methodParam)

Convert the value to the required type (if necessary from a String).

Conversions from String to any type will typically use the setAsText method of the PropertyEditor class. Note that a PropertyEditor must be registered for the given class for this to work; this is a standard JavaBeans API. A number of PropertyEditors are automatically registered.

Parameters
value the value to convert
requiredType the type we must convert to (or null if not known, for example in case of a collection element)
methodParam the method parameter that is the target of the conversion (for analysis of generic types; may be null)
Returns
  • the new value, possibly the result of type conversion

public PropertyEditor findCustomEditor (Class requiredType, String propertyPath)

Find a custom property editor for the given type and property.

Parameters
requiredType the type of the property (can be null if a property is given but should be specified in any case for consistency checking)
propertyPath the path of the property (name or nested path), or null if looking for an editor for all properties of the given type
Returns
  • the registered editor, or null if none

public String[] getAllowedFields ()

Return the fields that should be allowed for binding.

Returns
  • array of field names

public BindingErrorProcessor getBindingErrorProcessor ()

Return the strategy for processing binding errors.

public BindingResult getBindingResult ()

Return the BindingResult instance created by this DataBinder. This allows for convenient access to the binding results after a bind operation.

Returns
  • the BindingResult instance, to be treated as BindingResult or as Errors instance (Errors is a super-interface of BindingResult)

public ConversionService getConversionService ()

Return the associated ConversionService, if any.

public String[] getDisallowedFields ()

Return the fields that should not be allowed for binding.

Returns
  • array of field names

public BindException getErrors ()

This method is deprecated.
in favor of getBindingResult(). Use the BindException(BindingResult) constructor to create a BindException instance if still needed.

Return the Errors instance for this data binder.

Returns
  • the Errors instance, to be treated as Errors or as BindException

public String getObjectName ()

Return the name of the bound object.

public String[] getRequiredFields ()

Return the fields that are required for each binding process.

Returns
  • array of field names

public Object getTarget ()

Return the wrapped target object.

public Validator getValidator ()

Return the Validator to apply after each binding step, if any.

public void initBeanPropertyAccess ()

Initialize standard JavaBean property access for this DataBinder.

This is the default; an explicit call just leads to eager initialization.

public void initDirectFieldAccess ()

Initialize direct field access for this DataBinder, as alternative to the default bean property access.

public boolean isAutoGrowNestedPaths ()

Return whether "auto-growing" of nested paths has been activated.

public boolean isIgnoreInvalidFields ()

Return whether to ignore invalid fields when binding.

public boolean isIgnoreUnknownFields ()

Return whether to ignore unknown fields when binding.

public void registerCustomEditor (Class requiredType, String field, PropertyEditor propertyEditor)

Register the given custom property editor for the given type and property, or for all properties of the given type.

If the property path denotes an array or Collection property, the editor will get applied either to the array/Collection itself (the PropertyEditor has to create an array or Collection value) or to each element (the PropertyEditor has to create the element type), depending on the specified required type.

Note: Only one single registered custom editor per property path is supported. In the case of a Collection/array, do not register an editor for both the Collection/array and each element on the same property.

For example, if you wanted to register an editor for "items[n].quantity" (for all values n), you would use "items.quantity" as the value of the 'propertyPath' argument to this method.

Parameters
requiredType the type of the property. This may be null if a property is given but should be specified in any case, in particular in case of a Collection - making clear whether the editor is supposed to apply to the entire Collection itself or to each of its entries. So as a general rule: Do not specify null here in case of a Collection/array!
field the path of the property (name or nested path), or null if registering an editor for all properties of the given type
propertyEditor editor to register

public void registerCustomEditor (Class requiredType, PropertyEditor propertyEditor)

Register the given custom property editor for all properties of the given type.

Parameters
requiredType the type of the property
propertyEditor the editor to register

public void setAllowedFields (String... allowedFields)

Register fields that should be allowed for binding. Default is all fields. Restrict this for example to avoid unwanted modifications by malicious users when binding HTTP request parameters.

Supports "xxx*", "*xxx" and "*xxx*" patterns. More sophisticated matching can be implemented by overriding the isAllowed method.

Alternatively, specify a list of disallowed fields.

Parameters
allowedFields array of field names

public void setAutoGrowNestedPaths (boolean autoGrowNestedPaths)

Set whether this binder should attempt to "auto-grow" a nested path that contains a null value.

If "true", a null path location will be populated with a default object value and traversed instead of resulting in an exception. This flag also enables auto-growth of collection elements when accessing an out-of-bounds index.

Default is "true" on a standard DataBinder. Note that this feature is only supported for bean property access (DataBinder's default mode), not for field access.

public void setBindingErrorProcessor (BindingErrorProcessor bindingErrorProcessor)

Set the strategy to use for processing binding errors, that is, required field errors and PropertyAccessExceptions.

Default is a DefaultBindingErrorProcessor.

public void setConversionService (ConversionService conversionService)

Specify a Spring 3.0 ConversionService to use for converting property values, as an alternative to JavaBeans PropertyEditors.

public void setDisallowedFields (String... disallowedFields)

Register fields that should not be allowed for binding. Default is none. Mark fields as disallowed for example to avoid unwanted modifications by malicious users when binding HTTP request parameters.

Supports "xxx*", "*xxx" and "*xxx*" patterns. More sophisticated matching can be implemented by overriding the isAllowed method.

Alternatively, specify a list of allowed fields.

Parameters
disallowedFields array of field names

public void setExtractOldValueForEditor (boolean extractOldValueForEditor)

Set whether to extract the old field value when applying a property editor to a new value for a field.

Default is "true", exposing previous field values to custom editors. Turn this to "false" to avoid side effects caused by getters.

public void setIgnoreInvalidFields (boolean ignoreInvalidFields)

Set whether to ignore invalid fields, that is, whether to ignore bind parameters that have corresponding fields in the target object which are not accessible (for example because of null values in the nested path).

Default is "false". Turn this on to ignore bind parameters for nested objects in non-existing parts of the target object graph.

Note that this setting only applies to binding operations on this DataBinder, not to retrieving values via its BindingResult.

public void setIgnoreUnknownFields (boolean ignoreUnknownFields)

Set whether to ignore unknown fields, that is, whether to ignore bind parameters that do not have corresponding fields in the target object.

Default is "true". Turn this off to enforce that all bind parameters must have a matching field in the target object.

Note that this setting only applies to binding operations on this DataBinder, not to retrieving values via its BindingResult.

public void setMessageCodesResolver (MessageCodesResolver messageCodesResolver)

Set the strategy to use for resolving errors into message codes. Applies the given strategy to the underlying errors holder.

Default is a DefaultMessageCodesResolver.

public void setRequiredFields (String... requiredFields)

Register fields that are required for each binding process.

If one of the specified fields is not contained in the list of incoming property values, a corresponding "missing field" error will be created, with error code "required" (by the default binding error processor).

Parameters
requiredFields array of field names

public void setValidator (Validator validator)

Set the Validator to apply after each binding step.

public void validate ()

Invoke the specified Validator, if any.

Protected Methods

protected void applyPropertyValues (MutablePropertyValues mpvs)

Apply given property values to the target object.

Default implementation applies all of the supplied property values as bean property values. By default, unknown fields will be ignored.

Parameters
mpvs the property values to be bound (can be modified)

protected void checkAllowedFields (MutablePropertyValues mpvs)

Check the given property values against the allowed fields, removing values for fields that are not allowed.

Parameters
mpvs the property values to be bound (can be modified)

protected void checkRequiredFields (MutablePropertyValues mpvs)

Check the given property values against the required fields, generating missing field errors where appropriate.

Parameters
mpvs the property values to be bound (can be modified)

protected void doBind (MutablePropertyValues mpvs)

Actual implementation of the binding process, working with the passed-in MutablePropertyValues instance.

Parameters
mpvs the property values to bind, as MutablePropertyValues instance

protected AbstractPropertyBindingResult getInternalBindingResult ()

Return the internal BindingResult held by this DataBinder, as AbstractPropertyBindingResult.

protected ConfigurablePropertyAccessor getPropertyAccessor ()

Return the underlying PropertyAccessor of this binder's BindingResult.

protected PropertyEditorRegistry getPropertyEditorRegistry ()

Return the underlying TypeConverter of this binder's BindingResult.

protected SimpleTypeConverter getSimpleTypeConverter ()

Return this binder's underlying SimpleTypeConverter.

protected TypeConverter getTypeConverter ()

Return the underlying TypeConverter of this binder's BindingResult.

protected boolean isAllowed (String field)

Return if the given field is allowed for binding. Invoked for each passed-in property value.

The default implementation checks for "xxx*", "*xxx" and "*xxx*" matches, as well as direct equality, in the specified lists of allowed fields and disallowed fields. A field matching a disallowed pattern will not be accepted even if it also happens to match a pattern in the allowed list.

Can be overridden in subclasses.

Parameters
field the field to check
Returns
  • if the field is allowed