I wrote an EnumConverter that is described in Use enum in h:selectManyCheckbox? Everything was fine until we recognize that this converter does not work properly in primefaces editable datatable. The problem is that although I added an attribute inside getAsString and getAsObject methods as following:
#Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
if (value instanceof Enum) {
component.getAttributes().put(ATTRIBUTE_ENUM_TYPE, value.getClass());
return ((Enum<?>) value).name();
} else {
throw new ConverterException(new FacesMessage("Value is not an enum: " + value.getClass()));
}
}
public Object getAsObject(FacesContext context, UIComponent component, String value) {
Class<Enum> enumType = (Class<Enum>) component.getAttributes().get(ATTRIBUTE_ENUM_TYPE);
try {
return Enum.valueOf(enumType, value);
} catch (IllegalArgumentException e) {
throw new ConverterException(new FacesMessage("Value is not an enum of type: " + enumType));
}
}
In the latter method(getAsObject) could not find the attribute that I gave to the components attribute map. But out of the pprimefaces editable datatable everything is fine. Is there any solution to achieve this?
This problem is caused because the custom component attribute was not saved in the row state of the PrimeFaces datatable (it works fine in standard h:dataTable).
We're going to need to store this information elsewhere. In the view scope along with the component ID would be one way.
In the getAsString():
context.getViewRoot().getViewMap().put(ATTRIBUTE_ENUM_TYPE + component.getId(), value.getClass());
And in the getAsObject():
Class<Enum> enumType = (Class<Enum>) context.getViewRoot().getViewMap().get(ATTRIBUTE_ENUM_TYPE + component.getId());
Related
I am trying to write a custom converter for a nested object so that this object gets saved as string in Neo4j database.
I am using #Convert annotation on my field and passing ImageConverter.class which is my AttributeConverter class.
Everything works fine as expected and I am able to save string representation of Image class in Neo4j db.
However, now instead of single image I want to have List<Image> as my nested field. In this case, putting #Convert(ImageConverter.class) doesn't work.
I see that there is a class called ConverterBasedCollectionConverter which gets used when I have a field of type List<LocalDateTime.
However, I couldn't find any exammples on how to use this class in case of custom converters.
Please can anyone help me with this or if there is any other approach to use custom converter on field of type List.
I am using Neo4j (version 3.4.1) and Spring-data-neo4j (5.0.10.RELEASE) in my application. I am also using OGM.
PS: I am aware that it is advised to store nested objects as separate node establishing a relationship with parent object. However, my use case demands that the object be stored as string property and not as separate node.
Regards,
V
It is not so difficult as I assumed it would be.
Given a class (snippet)
#NodeEntity
public class Actor {
#Id #GeneratedValue
private Long id;
#Convert(MyImageListConverter.class)
public List<MyImage> images = new ArrayList<>();
// ....
}
with MyImage as simple as can be
public class MyImage {
public String blob;
public MyImage(String blob) {
this.blob = blob;
}
public static MyImage of(String value) {
return new MyImage(value);
}
}
and a converter
public class MyImageListConverter implements AttributeConverter<List<MyImage>, String[]> {
#Override
public String[] toGraphProperty(List<MyImage> value) {
if (value == null) {
return null;
}
String[] values = new String[(value.size())];
int i = 0;
for (MyImage image : value) {
values[i++] = image.blob;
}
return values;
}
#Override
public List<MyImage> toEntityAttribute(String[] values) {
List<MyImage> images = new ArrayList<>(values.length);
for (String value : values) {
images.add(MyImage.of(value));
}
return images;
}
}
will print following debug output on save that I think is what you want:
UNWIND {rows} as row CREATE (n:Actor) SET n=row.props RETURN row.nodeRef as ref, ID(n) as id, {type} as type with params {type=node, rows=[{nodeRef=-1, props={images=[blobb], name=Jeff}}]}
especially the images part.
Test method for this looks like
#Test
public void test() {
Actor jeff = new Actor("Jeff");
String blobValue = "blobb";
jeff.images.add(new MyImage(blobValue));
session.save(jeff);
session.clear();
Actor loadedActor = session.load(Actor.class, jeff.getId());
assertThat(loadedActor.images.get(0).blob).isEqualTo(blobValue);
}
I am came up with a solution to my problem. So, in case you want another solution along with the solution provided by #meistermeier, you can use the below code.
public class ListImageConverter extends ConverterBasedCollectionConverter<Image, String>{
public ListImageConverter() {
super(List.class, new ImageConverter());
}
#Override
public String[] toGraphProperty(Collection<Image> values) {
Object[] graphProperties = super.toGraphProperty(values);
String[] stringArray = Arrays.stream(graphProperties).toArray(String[]::new);
return stringArray;
}
#Override
public Collection<Image> toEntityAttribute(String[] values) {
return super.toEntityAttribute(values);
}
}
ImageConverter class just implements AttributeConverter<Image, String> where I serialize and deserialize my Image object to/from json.
I chose to go with this approach because I had Image field in one object and List<Image> in another object. So just by changing #Convert(ListImageConverter.class) to #Convert(ImageConverter.class) I was able to save list as well as single object in Neo4j database.
Note: You can skip overriding toEntityAttribute method if you want. It doesn't add much value.
However you have to override toGraphProperty as within Neo4j code it checks for presence of declared method with name toGraphProperty.
Hope this helps someone!
Regards,
V
I am creating a web application, where you have to read a list of objects / entities from a DB and populate it in a JSF <h:selectOneMenu>. I am unable to code this. Can someone show me how to do it?
I know how to get a List<User> from the DB. What I need to know is, how to populate this list in a <h:selectOneMenu>.
<h:selectOneMenu value="#{bean.name}">
...?
</h:selectOneMenu>
Based on your question history, you're using JSF 2.x. So, here's a JSF 2.x targeted answer. In JSF 1.x you would be forced to wrap item values/labels in ugly SelectItem instances. This is fortunately not needed anymore in JSF 2.x.
Basic example
To answer your question directly, just use <f:selectItems> whose value points to a List<T> property which you preserve from the DB during bean's (post)construction. Here's a basic kickoff example assuming that T actually represents a String.
<h:selectOneMenu value="#{bean.name}">
<f:selectItems value="#{bean.names}" />
</h:selectOneMenu>
with
#ManagedBean
#RequestScoped
public class Bean {
private String name;
private List<String> names;
#EJB
private NameService nameService;
#PostConstruct
public void init() {
names = nameService.list();
}
// ... (getters, setters, etc)
}
Simple as that. Actually, the T's toString() will be used to represent both the dropdown item label and value. So, when you're instead of List<String> using a list of complex objects like List<SomeEntity> and you haven't overridden the class' toString() method, then you would see com.example.SomeEntity#hashcode as item values. See next section how to solve it properly.
Also note that the bean for <f:selectItems> value does not necessarily need to be the same bean as the bean for <h:selectOneMenu> value. This is useful whenever the values are actually applicationwide constants which you just have to load only once during application's startup. You could then just make it a property of an application scoped bean.
<h:selectOneMenu value="#{bean.name}">
<f:selectItems value="#{data.names}" />
</h:selectOneMenu>
Complex objects as available items
Whenever T concerns a complex object (a javabean), such as User which has a String property of name, then you could use the var attribute to get hold of the iteration variable which you in turn can use in itemValue and/or itemLabel attribtues (if you omit the itemLabel, then the label becomes the same as the value).
Example #1:
<h:selectOneMenu value="#{bean.userName}">
<f:selectItems value="#{bean.users}" var="user" itemValue="#{user.name}" />
</h:selectOneMenu>
with
private String userName;
private List<User> users;
#EJB
private UserService userService;
#PostConstruct
public void init() {
users = userService.list();
}
// ... (getters, setters, etc)
Or when it has a Long property id which you would rather like to set as item value:
Example #2:
<h:selectOneMenu value="#{bean.userId}">
<f:selectItems value="#{bean.users}" var="user" itemValue="#{user.id}" itemLabel="#{user.name}" />
</h:selectOneMenu>
with
private Long userId;
private List<User> users;
// ... (the same as in previous bean example)
Complex object as selected item
Whenever you would like to set it to a T property in the bean as well and T represents an User, then you would need to bake a custom Converter which converts between User and an unique string representation (which can be the id property). Do note that the itemValue must represent the complex object itself, exactly the type which needs to be set as selection component's value.
<h:selectOneMenu value="#{bean.user}" converter="#{userConverter}">
<f:selectItems value="#{bean.users}" var="user" itemValue="#{user}" itemLabel="#{user.name}" />
</h:selectOneMenu>
with
private User user;
private List<User> users;
// ... (the same as in previous bean example)
and
#ManagedBean
#RequestScoped
public class UserConverter implements Converter {
#EJB
private UserService userService;
#Override
public Object getAsObject(FacesContext context, UIComponent component, String submittedValue) {
if (submittedValue == null || submittedValue.isEmpty()) {
return null;
}
try {
return userService.find(Long.valueOf(submittedValue));
} catch (NumberFormatException e) {
throw new ConverterException(new FacesMessage(String.format("%s is not a valid User ID", submittedValue)), e);
}
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object modelValue) {
if (modelValue == null) {
return "";
}
if (modelValue instanceof User) {
return String.valueOf(((User) modelValue).getId());
} else {
throw new ConverterException(new FacesMessage(String.format("%s is not a valid User", modelValue)), e);
}
}
}
(please note that the Converter is a bit hacky in order to be able to inject an #EJB in a JSF converter; normally one would have annotated it as #FacesConverter(forClass=User.class), but that unfortunately doesn't allow #EJB injections)
Don't forget to make sure that the complex object class has equals() and hashCode() properly implemented, otherwise JSF will during render fail to show preselected item(s), and you'll on submit face Validation Error: Value is not valid.
public class User {
private Long id;
#Override
public boolean equals(Object other) {
return (other != null && getClass() == other.getClass() && id != null)
? id.equals(((User) other).id)
: (other == this);
}
#Override
public int hashCode() {
return (id != null)
? (getClass().hashCode() + id.hashCode())
: super.hashCode();
}
}
Complex objects with a generic converter
Head to this answer: Implement converters for entities with Java Generics.
Complex objects without a custom converter
The JSF utility library OmniFaces offers a special converter out the box which allows you to use complex objects in <h:selectOneMenu> without the need to create a custom converter. The SelectItemsConverter will simply do the conversion based on readily available items in <f:selectItem(s)>.
<h:selectOneMenu value="#{bean.user}" converter="omnifaces.SelectItemsConverter">
<f:selectItems value="#{bean.users}" var="user" itemValue="#{user}" itemLabel="#{user.name}" />
</h:selectOneMenu>
See also:
Our <h:selectOneMenu> wiki page
View-Page
<h:selectOneMenu id="selectOneCB" value="#{page.selectedName}">
<f:selectItems value="#{page.names}"/>
</h:selectOneMenu>
Backing-Bean
List<SelectItem> names = new ArrayList<SelectItem>();
//-- Populate list from database
names.add(new SelectItem(valueObject,"label"));
//-- setter/getter accessor methods for list
To display particular selected record, it must be one of the values in the list.
Roll-your-own generic converter for complex objects as selected item
The Balusc gives a very useful overview answer on this subject. But there is one alternative he does not present: The Roll-your-own generic converter that handles complex objects as the selected item. This is very complex to do if you want to handle all cases, but pretty simple for simple cases.
The code below contains an example of such a converter. It works in the same spirit as the OmniFaces SelectItemsConverter as it looks through the children of a component for UISelectItem(s) containing objects. The difference is that it only handles bindings to either simple collections of entity objects, or to strings. It does not handle item groups, collections of SelectItems, arrays and probably a lot of other things.
The entities that the component binds to must implement the IdObject interface. (This could be solved in other way, such as using toString.)
Note that the entities must implement equals in such a way that two entities with the same ID compares equal.
The only thing that you need to do to use it is to specify it as converter on the select component, bind to an entity property and a list of possible entities:
<h:selectOneMenu value="#{bean.user}" converter="selectListConverter">
<f:selectItem itemValue="unselected" itemLabel="Select user..."/>
<f:selectItem itemValue="empty" itemLabel="No user"/>
<f:selectItems value="#{bean.users}" var="user" itemValue="#{user}" itemLabel="#{user.name}" />
</h:selectOneMenu>
Converter:
/**
* A converter for select components (those that have select items as children).
*
* It convertes the selected value string into one of its element entities, thus allowing
* binding to complex objects.
*
* It only handles simple uses of select components, in which the value is a simple list of
* entities. No ItemGroups, arrays or other kinds of values.
*
* Items it binds to can be strings or implementations of the {#link IdObject} interface.
*/
#FacesConverter("selectListConverter")
public class SelectListConverter implements Converter {
public static interface IdObject {
public String getDisplayId();
}
#Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
if (value == null || value.isEmpty()) {
return null;
}
return component.getChildren().stream()
.flatMap(child -> getEntriesOfItem(child))
.filter(o -> value.equals(o instanceof IdObject ? ((IdObject) o).getDisplayId() : o))
.findAny().orElse(null);
}
/**
* Gets the values stored in a {#link UISelectItem} or a {#link UISelectItems}.
* For other components returns an empty stream.
*/
private Stream<?> getEntriesOfItem(UIComponent child) {
if (child instanceof UISelectItem) {
UISelectItem item = (UISelectItem) child;
if (!item.isNoSelectionOption()) {
return Stream.of(item.getValue());
}
} else if (child instanceof UISelectItems) {
Object value = ((UISelectItems) child).getValue();
if (value instanceof Collection) {
return ((Collection<?>) value).stream();
} else {
throw new IllegalStateException("Unsupported value of UISelectItems: " + value);
}
}
return Stream.empty();
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
if (value == null) return null;
if (value instanceof String) return (String) value;
if (value instanceof IdObject) return ((IdObject) value).getDisplayId();
throw new IllegalArgumentException("Unexpected value type");
}
}
I'm doing it like this:
Models are ViewScoped
converter:
#Named
#ViewScoped
public class ViewScopedFacesConverter implements Converter, Serializable
{
private static final long serialVersionUID = 1L;
private Map<String, Object> converterMap;
#PostConstruct
void postConstruct(){
converterMap = new HashMap<>();
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object object) {
String selectItemValue = String.valueOf( object.hashCode() );
converterMap.put( selectItemValue, object );
return selectItemValue;
}
#Override
public Object getAsObject(FacesContext context, UIComponent component, String selectItemValue){
return converterMap.get(selectItemValue);
}
}
and bind to component with:
<f:converter binding="#{viewScopedFacesConverter}" />
If you will use entity id rather than hashCode you can hit a collision- if you have few lists on one page for different entities (classes) with the same id
Call me lazy but coding a Converter seems like a lot of unnecessary work. I'm using Primefaces and, not having used a plain vanilla JSF2 listbox or dropdown menu before, I just assumed (being lazy) that the widget could handle complex objects, i.e. pass the selected object as is to its corresponding getter/setter like so many other widgets do. I was disappointed to find (after hours of head scratching) that this capability does not exist for this widget type without a Converter. In fact if you supply a setter for the complex object rather than for a String, it fails silently (simply doesn't call the setter, no Exception, no JS error), and I spent a ton of time going through BalusC's excellent troubleshooting tool to find the cause, to no avail since none of those suggestions applied. My conclusion: listbox/menu widget needs adapting that other JSF2 widgets do not. This seems misleading and prone to leading the uninformed developer like myself down a rabbit hole.
In the end I resisted coding a Converter and found through trial and error that if you set the widget value to a complex object, e.g.:
<p:selectOneListbox id="adminEvents" value="#{testBean.selectedEvent}">
... when the user selects an item, the widget can call a String setter for that object, e.g. setSelectedThing(String thingString) {...}, and the String passed is a JSON String representing the Thing object. I can parse it to determine which object was selected. This feels a little like a hack, but less of a hack than a Converter.
Hi I'm trying to create a custom component that extends UIInput. In that component I generate one html input, one html submit button and one line of text. The codes are as below:
#Override
public void decode(FacesContext context) {
Map requestMap = context.getExternalContext().getRequestParameterMap();
String clientId = getClientId(context);
char sep = UINamingContainer.getSeparatorChar(context);
String symbol = ((String) requestMap.get(clientId + sep + "inputfield"));
setSubmittedValue(symbol);
}
#Override
public void encodeEnd(FacesContext context) throws IOException {
String clientId = getClientId(context);
char sep = UINamingContainer.getSeparatorChar(context);
//-----------------------this generates an html input-------------------------
encodeInputField(context, clientId + sep + "inputfield");
//Now if I uncomment the next line it generates another html, whose value always stays the same as the first one
//encodeInputField(context, clientId + sep + "inputfield2");
encodeSubmitButton(context, clientId + sep + "submit");
encodeOutputField(context);
}
private void encodeInputField(FacesContext context, String clientId) throws IOException {
// Render a standard HTML input field
ResponseWriter writer = context.getResponseWriter();
writer.startElement("input", this);
writer.writeAttribute("type", "text", null);
writer.writeAttribute("name", clientId, "clientId");
Object value = getValue();
if (value != null) {
writer.writeAttribute("value", value.toString(), "value");
}
writer.writeAttribute("size", "6", null);
writer.endElement("input");
}
private void encodeSubmitButton(FacesContext context, String clientId) throws IOException {
// render a submit button
ResponseWriter writer = context.getResponseWriter();
writer.startElement("input", this);
writer.writeAttribute("type", "Submit", null);
writer.writeAttribute("name", clientId, "clientId");
writer.writeAttribute("value", "Click Me!", null);
writer.endElement("input");
}
private void encodeOutputField(FacesContext context) throws IOException {
ResponseWriter writer = context.getResponseWriter();
//----------------weird value that comes out of nowhere-----------------------
String hellomsg = (String) getAttributes().get("value");
writer.startElement("p", this);
writer.writeText("You entered: " + hellomsg, null);
writer.endElement("p");
}
Now everything works fine but I don't understand where the value attribute in String hellomsg = (String) getAttributes().get("value"); comes. I tried to debug this program and the getAttributes() hashmap also contains weird entries and I couldn't find any entry whose key is "value".
Finally if I generate two html input then the second input's value always stays the same as the first one.
I also noticed that I can include a value in the tag, e.g. <mycc:cinput value="yes"> and when the page loads, the value of the html input generated is set to yes.
My doubt is: is every UIInput has a default value attribute? If so, is that attribute value always linked to whatever html input's value attribute? If so, is it always linked to the value attribute of the first html input generated?
Thanks in advance for reading such a long question. If possible can you guys let me know where I can find answers to issues like this? Im getting a headache browsing random google search results#_#
Thanks a lot!
Now everything works fine but I don't understand where the value attribute in String hellomsg = (String) getAttributes().get("value"); comes. I tried to debug this program and the getAttributes() hashmap also contains weird entries and I couldn't find any entry whose key is "value".
Read the javadoc of UIComponent#getAttributes(). To the point, it's really an abstract map. The get("value") doesn't really return an entry from the map, but it basically obtains the value property of the component itself by invoking its getValue() method, if any available (and it is, in case of UIInput). But if you're already sitting in the component itself, you don't need to invoke getAttributes().get("value"), you can just invoke the getValue() method directly.
Note thus that if you intend to put a custom attribute in the attribute map, then you should be using a different name, or, better, to make use of StateHelper.
See also:
JSF custom component: support for arguments of custom types, the attribute setter is never invoked
How to save state when extending UIComponentBase
I'm working with the multiple row selection to give a user ability to delete the selecting records. According to the PDF documentation, and the ShowCase Labs, I must use the code translated to the Java like that:
final DataTable = new DataTable();
...
// (1)
dataTable.setSelectionMode("multiple");
// (2)
dataTable.setValueExpression("selection", createValueExpression(DbeBean.class, "selection", Object[].class));
// (3)
dataTable.setValueExpression("rowKey", createValueExpression("#{" + VARIABLE + ".indexKey}", Object.class));
...
final ClientBehaviorHolder dataTableAsHolder = dataTable;
...
// (4)
dataTableAsHolder.addClientBehavior("rowSelect", createAjaxBehavior(createMethodExpression(metaData.controllerBeanType, "onRowSelect", void.class, new Class<?>[] {SelectEvent.class})));
multiple - This line features the multiple selection, works fine visually at the front-end.
selection - Being invoked, the #{dbeBean.selection} is really bound and the public void setSelection(T[] selection) is only invoked.
rowKey - Being invoked, works fine, the getIndexKey() is invoked and returns the necessary result.
rowSelect - This event handler is invoked too, DbeBean.onRowSelect(SelectEvent e).
I also use lazy data model (I don't really believe it may be the reason but who knows?; by the way, it returns List<T> though setSelection() requires T[] -- why it's like that?):
public abstract class AbstractLazyDataSource<T extends IIndexable<K>, K> extends LazyDataModel<T> {
...
#Override
public final List<T> load(int first, int pageSize, String sortField, SortOrder sortOrder, Map<String, String> filters) {
...
final IResultContainer<T> resultContainer = getData(querySpecifier);
final List<T> data = resultContainer.getData();
setRowCount(resultContainer.getTotalEntitiesCount());
return getPage(data, first, pageSize);
}
...
#Override
public final K getRowKey(T object) {
return object.getIndexKey(); // T instanceof IIndexable<K>, have to return a unique ID
}
...
However, the handlers do not work as they are expected to work. Please help me to understand why (2) DbeBean.setSelection(T[] selection) & (4) DbeBean.onRowSelect(SelectEvent e) get only the null value: T[] selection = null, and SelectEvent: e.getObject = null, respectively. What am I doing wrong?
Thanks in advance.
PrimeFaces 3.2
Mojarra 2.1.7
I've got it to work: I simply removed the rowKey property during to the dynamic p:dataTable creation (DataTable), and simply overloaded getRowData in lazy data model. Now it works.
This question already has answers here:
Validation Error: Value is not valid
(3 answers)
Closed 7 years ago.
I got this error many time.. i am using two h:selectonemenu in my JSF page, mediaList and Unitlist. while selecting any Media . my UnitList populate automatically, but some time it gives Validation Error: value is not valid;
My JSF code
<h:selectOneMenu id="media" value="#{workOrderMbean.selectedMedia}" converter="MediaConverter" onchange="submit()" valueChangeListener="#{workOrderMbean.onChangeMediaCombo}" immediate="true">
<f:selectItems value="#{workOrderMbean.mediaCombo}"/>
</h:selectOneMenu>
<h:selectOneMenu id="hUnit" value="#{workOrderMbean.selectedHeightUnit}" converter="UnitConverter" >
<f:selectItems value="#{workOrderMbean.unitCombo}"/>
</h:selectOneMenu>
onchane event of Mediacombo is
public void onChangeMediaCombo(ValueChangeEvent e) throws SearchBLException {
if (e.getNewValue() != null) {
Media media = (Media) e.getNewValue();
if (unitCombo != null && !unitCombo.isEmpty()) {
unitCombo.clear();
seclectedWidthUnit=new Unit();
selectedHeightUnit=new Unit();
}
unitCombo = ComboLoader.getUnitsComboByMediaid(media.getMediaId());
}
else
{
if (unitCombo != null && !unitCombo.isEmpty()) {
unitCombo.clear();
seclectedWidthUnit=null;
selectedHeightUnit=null;
}
unitCombo = ComboLoader.getUnitsComboByMediaid(-1);
}
}
i am also using converter for 'Unit'
my media converter is
#FacesConverter(value = "MediaConverter")
public class MediaConverter implements Converter{
MediaDAO mediadao=new MediaDAOImpl();
public Object getAsObject(FacesContext context, UIComponent component, String value) {
Media media=null;
try {
media=mediadao.getMedia(Integer.parseInt(value));
} catch (SearchBLException ex) {
Logger.getLogger(MediaConverter.class.getName()).log(Level.SEVERE, null, ex);
}
return media;
}
public String getAsString(FacesContext context, UIComponent component, Object value) {
String str = "";
if (value instanceof Media) {
str = "" + ((Media) value).getMediaId();
}
return str;
}
}
The problem is most likely in your converter and model class (Media).
You don't show how you exactly do the conversion, but I guess you're converting to String by returning the Media's Id, and converting back to Media by getting a new instance from some place like a DB?
In that case, your Media class needs to implement a custom equals and hashcode method.
JSF compares if the value send by the user corresponds with the values in the list you bind to the selectitems. It uses equals for that, which by default compares object Ids (kind of memory references). Unless you have the exact same instances, this will always be false.
Instead of defining an equals method, you can alternatively let your converter get the model object you need from the same list as the selectitems come from. There was an article on http://jdevelopment.nl a while back about this.