Primefaces selectOneMenu转换器已调用但不起作用

Question

I've looked at the other questions this and this , etc, the problem is that my convert gets called but the values of selectOneMenu doesn't change . My entity class is generated, and has equals as well as hashCode and I would like not to change anything in it - if it gets regenerated then all changes will be lost (The work around is to change toString of the entity class).

The XHTML code snipped:

<p:selectOneMenu id="defid" 
                 value="#{abcController.selected.defid}"
                 converter="defConverter">

The Converter:

@FacesConverter("defConverter")
public class DefConverter implements Converter
{
    private static final Logger LOG = Logger.getLogger(DefConverter.class.getName());
    @EJB
    private DefFacade defFacade;

    @Override
    public Object getAsObject(FacesContext fc, UIComponent uic, String string)
    {
        LOG.info("getAsObject: " + string);
        try
        {
            return defFacade.findWithNFieldsWithValue("name", string, "=").get(0);
        }
        catch (Exception ex)
        {
            LOG.log(Level.SEVERE, "Error while fetching Def for " + string, ex);
        }
        return null;
    }

    @Override
    public String getAsString(FacesContext fc, UIComponent uic, Object obj)
    {
        LOG.info("getAsString obj class: " + obj.getClass().getName());
        if(obj instanceof Def)
        {
            Def def = (Def)obj;
            LOG.info("getAsString def name: " + def.getName());
            return def.getName();
        }
        else
        {
            StringBuilder sbError = new StringBuilder("The object of class ");
            sbError.append(obj.getClass().getName()).append(" is not of Def");
            throw new ClassCastException(sbError.toString());
        }
    }
}

The entity class snipped (this is generated):

...
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "defid")
private Long defid;
...

@Override
public int hashCode()
{
    int hash = 0;
    hash += (defid != null ? defid.hashCode() : 0);
    return hash;
}

@Override
public boolean equals(Object object)
{
    // TODO: Warning - this method won't work in the case the id fields are not set
    if (!(object instanceof Def))
    {
        return false;
    }
    Def other = (Def) object;
    if ((this.defid == null && other.defid != null) || (this.defid != null && !this.defid.equals(other.defid)))
    {
        return false;
    }
    return true;
}

When the page loads, I can see the log statements as follow:

getAsString obj class: com.xyz.Def
getAsString def name: Name 1
getAsString obj class: com.xyz.Def
getAsString def name: Name 2
getAsString obj class: com.xyz.Def
getAsString def name: Name 3

Thus the converter gets called and returns the correct values but on the page it is still com.xyz.Def[ defid=1 ] (Drop down and normal)

Answer 1

The converter seems to be working, but you didn't post the whole <p:selectOneMenu> code, in particular <f:selectItems> . It should look something like this

<p:selectOneMenu id="defid" 
                 value="#{abcController.selected.defid}"
                 converter="defConverter">
    <f:selectItems value="#{abcController.defs}" var="def"
                       itemLabel="#{def.name}" itemValue="#{def.defId}" />
</p:selectOneMenu>

itemLabel is responsible for printing displayed values.

Answer 2

Try the following code

<p:selectOneMenu id="defid" value="#{abcController.selected.def}"
             converter="defConverter">
   <f:selectItems value="#{abcController.defs}" var="def" 
        itemValue="#{def}" itemLabel="#{def.name}" />       
</p:selectOneMenu>

Converter is used to convert between a complex Java object and a String representation. For this you need to specify the whole def object as item value instead. You should also ensure that #{abcController.selected.def} refers to a def property, not some Long property representing the def ID.