DataBinder for data binding from web request parameters
to JavaBean objects. Designed for web environments, but not dependent on
the Servlet API; serves as base class for more specific DataBinder variants,
such as org.springframework.web.bind.ServletRequestDataBinder .Warning
Data binding can lead to security issues by exposing parts of the object graph that are not meant to be accessed or modified by external clients. Therefore, the design and use of data binding should be considered carefully with regard to security. For more details, please refer to the dedicated sections on data binding for Spring Web MVC and Spring WebFlux in the reference manual.
Includes support for field markers which address a common problem with HTML checkboxes and select options: detecting that a field was part of the form, but did not generate a request parameter because it was empty. A field marker allows to detect that state and reset the corresponding bean property accordingly. Default values, for parameters that are otherwise not present, can specify a value for the field other than empty.
registerCustomEditor, setAllowedFields, setRequiredFields, setFieldMarkerPrefix, setFieldDefaultPrefix, ServletRequestDataBinder
| Modifier and Type | Field and Description |
|---|---|
| private boolean | |
| public static final String | DEFAULT_FIELD_DEFAULT_PREFIX
Default prefix that field default parameters start with, followed by the field name: e.g. "!subscribeToNewsletter" for a field "subscribeToNewsletter". |
| public static final String | DEFAULT_FIELD_MARKER_PREFIX
Default prefix that field marker parameters start with, followed by the field name: e.g. "_subscribeToNewsletter" for a field "subscribeToNewsletter". |
| private String | |
| private String |
| Access | Constructor and Description |
|---|---|
| public | WebDataBinder(Object
the target object to bind onto (or target)null
if the binder is just used to convert a plain parameter value)Create a new WebDataBinder instance, with default object name. |
| public | WebDataBinder(Object
the target object to bind onto (or target, String null
if the binder is just used to convert a plain parameter value)the name of the target object objectName)Create a new WebDataBinder instance. |
| Modifier and Type | Method and Description |
|---|---|
| protected void | adaptEmptyArrayIndices(MutablePropertyValues
the property values to be bound (can be modified) mpvs)Check for property values with names that end on |
| protected void | bindMultipart(Map<String, List<MultipartFile>>
a Map of field name String to MultipartFile object multipartFiles, MutablePropertyValues the property values to be bound (can be modified) mpvs)Bind all multipart files contained in the given request, if any (in case of a multipart request). |
| protected void | checkFieldDefaults(MutablePropertyValues
the property values to be bound (can be modified) mpvs)Check the given property values for field defaults, i.e. for fields that start with the field default prefix. |
| protected void | checkFieldMarkers(MutablePropertyValues
the property values to be bound (can be modified) mpvs)Check the given property values for field markers, i.e. for fields that start with the field marker prefix. |
| protected void | doBind(MutablePropertyValues
the property values to bind,
as MutablePropertyValues instance mpvs)
This implementation performs a field default and marker check
before delegating to the superclass binding process.
|
| protected Object | Returns: the empty value (for most fields:null)the name of the field field, Class<?> the type of the field fieldType)Determine an empty value for the specified field. |
| public Object | Returns: the empty value (for most fields:null)the type of the field fieldType)Determine an empty value for the specified field. |
| public String | |
| public String | |
| public boolean | |
| protected Object | Returns: the resolved value, ornullthe name of the value to resolve name, Class<?> the type of value expected type, BiFunction<String, Class<?>, Object> delegate resolver to use for the checks resolver)Check if a value can be resolved if |
| public void | setBindEmptyMultipartFiles(boolean bindEmptyMultipartFiles)
Set whether to bind empty MultipartFile parameters. |
| public void | setFieldDefaultPrefix(String fieldDefaultPrefix)
Specify a prefix that can be used for parameters that indicate default value fields, having "prefix + field" as name. |
| public void | setFieldMarkerPrefix(String fieldMarkerPrefix)
Specify a prefix that can be used for parameters that mark potentially empty fields, having "prefix + field" as name. |
| bindEmptyMultipartFiles | back to summary |
|---|---|
| private boolean bindEmptyMultipartFiles | |
| DEFAULT_FIELD_DEFAULT_PREFIX | back to summary |
|---|---|
| public static final String DEFAULT_FIELD_DEFAULT_PREFIX Default prefix that field default parameters start with, followed by the field name: e.g. "!subscribeToNewsletter" for a field "subscribeToNewsletter". Default parameters differ from field markers in that they provide a default value instead of an empty value.
| |
| DEFAULT_FIELD_MARKER_PREFIX | back to summary |
|---|---|
| public static final String DEFAULT_FIELD_MARKER_PREFIX Default prefix that field marker parameters start with, followed by the field name: e.g. "_subscribeToNewsletter" for a field "subscribeToNewsletter". Such a marker parameter indicates that the field was visible, that is, existed in the form that caused the submission. If no corresponding field value parameter was found, the field will be reset. The value of the field marker parameter does not matter in this case; an arbitrary value can be used. This is particularly useful for HTML checkboxes and select options.
| |
| fieldDefaultPrefix | back to summary |
|---|---|
| private String fieldDefaultPrefix
| |
| fieldMarkerPrefix | back to summary |
|---|---|
| private String fieldMarkerPrefix
| |
| WebDataBinder | back to summary |
|---|---|
| public WebDataBinder(Object target) Create a new WebDataBinder instance, with default object name.
| |
| WebDataBinder | back to summary |
|---|---|
| public WebDataBinder(Object target, String objectName) Create a new WebDataBinder instance. | |
| adaptEmptyArrayIndices | back to summary |
|---|---|
| protected void adaptEmptyArrayIndices(MutablePropertyValues mpvs) Check for property values with names that end on
| |
| bindMultipart | back to summary |
|---|---|
| protected void bindMultipart(Map<String, List<MultipartFile>> multipartFiles, MutablePropertyValues mpvs) Bind all multipart files contained in the given request, if any (in case of a multipart request). To be called by subclasses. Multipart files will only be added to the property values if they are not empty or if we're configured to bind empty multipart files too.
| |
| checkFieldDefaults | back to summary |
|---|---|
| protected void checkFieldDefaults(MutablePropertyValues mpvs) Check the given property values for field defaults, i.e. for fields that start with the field default prefix. The existence of a field defaults indicates that the specified value should be used if the field is otherwise not present.
| |
| checkFieldMarkers | back to summary |
|---|---|
| protected void checkFieldMarkers(MutablePropertyValues mpvs) Check the given property values for field markers, i.e. for fields that start with the field marker prefix. The existence of a field marker indicates that the specified field existed in the form. If the property values do not contain a corresponding field value, the field will be considered as empty and will be reset appropriately.
| |
| doBind | back to summary |
|---|---|
| protected void doBind(MutablePropertyValues mpvs) Overrides org. This implementation performs a field default and marker check before delegating to the superclass binding process.
| |
| getEmptyValue | back to summary |
|---|---|
| protected Object getEmptyValue(String field, Class<?> fieldType) Determine an empty value for the specified field. The default implementation delegates to | |
| getEmptyValue | back to summary |
|---|---|
| public Object getEmptyValue(Class<?> fieldType) Determine an empty value for the specified field. The default implementation returns:
| |
| getFieldDefaultPrefix | back to summary |
|---|---|
| public String getFieldDefaultPrefix() Return the prefix for parameters that mark default fields.
| |
| getFieldMarkerPrefix | back to summary |
|---|---|
| public String getFieldMarkerPrefix() Return the prefix for parameters that mark potentially empty fields.
| |
| isBindEmptyMultipartFiles | back to summary |
|---|---|
| public boolean isBindEmptyMultipartFiles() Return whether to bind empty MultipartFile parameters. | |
| resolvePrefixValue | back to summary |
|---|---|
| protected Object resolvePrefixValue(String name, Class<?> type, BiFunction<String, Class<?>, Object> resolver) Check if a value can be resolved if | |
| setBindEmptyMultipartFiles | back to summary |
|---|---|
| public void setBindEmptyMultipartFiles(boolean bindEmptyMultipartFiles) Set whether to bind empty MultipartFile parameters. Default is "true". Turn this off if you want to keep an already bound MultipartFile when the user resubmits the form without choosing a different file. Else, the already bound MultipartFile will be replaced by an empty MultipartFile holder. | |
| setFieldDefaultPrefix | back to summary |
|---|---|
| public void setFieldDefaultPrefix(String fieldDefaultPrefix) Specify a prefix that can be used for parameters that indicate default value fields, having "prefix + field" as name. The value of the default field is used when the field is not provided. Default is "!", for "!FIELD" parameters (e.g. "!subscribeToNewsletter"). Set this to null if you want to turn off the field defaults completely. HTML checkboxes only send a value when they're checked, so it is not possible to detect that a formerly checked box has just been unchecked, at least not with standard HTML means. A default field is especially useful when a checkbox represents a non-boolean value. The presence of a default parameter preempts the behavior of a field marker for the given field.
| |
| setFieldMarkerPrefix | back to summary |
|---|---|
| public void setFieldMarkerPrefix(String fieldMarkerPrefix) Specify a prefix that can be used for parameters that mark potentially empty fields, having "prefix + field" as name. Such a marker parameter is checked by existence: You can send any value for it, for example "visible". This is particularly useful for HTML checkboxes and select options. Default is "_", for "_FIELD" parameters (e.g. "_subscribeToNewsletter"). Set this to null if you want to turn off the empty field check completely. HTML checkboxes only send a value when they're checked, so it is not possible to detect that a formerly checked box has just been unchecked, at least not with standard HTML means. One way to address this is to look for a checkbox parameter value if
you know that the checkbox has been visible in the form, resetting the
checkbox if no value found. In Spring web MVC, this typically happens
in a custom This auto-reset mechanism addresses this deficiency, provided that a marker parameter is sent for each checkbox field, like "_subscribeToNewsletter" for a "subscribeToNewsletter" field. As the marker parameter is sent in any case, the data binder can detect an empty field and automatically reset its value.
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