Wicket - DropDownChoice + ChoiceRenderer - 预选不起作用

Question

我正在我的Web应用程序中创建一个带有选择框的表单.我以下面描述的方式使用DropDownChoice + ChoiceRenderer组合.它工作正常,但一方面 - in不预先选择默认值.

我一直在努力解决这个问题很长一段时间.我在互联网上找到了几个据说可行的例子,但它们对我不起作用.

我的代码库看起来像这样(不相关的部分已被省略或简化以提高清晰度):

商业实体

public class MultivalueType
{
    private Long id;
    private String label;
    private String description;

    public MultivalueType(Long id, String label, String description) 
    {
        this.id = id
        this.label = label;
        this.description = description;
    }

    public Long getId()
    {
        return id;
    }

    public String getLabel() 
    {
        return label;
    }

    public String getDescription() 
    {
        return description;
    }
}

public class PropertySettings
{
    private Long id;
    private String property;
    private MultivalueType multivalueType;

    public PropertySettings(Long id, String property, MultivalueType multivalueType) 
    {
        this.id = id;
        this.property = property;
        this.multivalueType = multivalueType;
    }

    public MultivalueType getMultivalueType()
    {
        return multivalueType;
    }
}

DAO

public class PropertySettingsDao
{
    ...
    @Override
    public PropertySettings load(Long id)
    {
        String query = " ... query ... ";
        Object[] params = { id };
        return getJdbcTemplate().queryForObject(query, params, getRowMapper());
}
    ...
}

表格类

PropertySettings property = propertySettingsDao.load(propertyId);
IModel<PropertySettings> formModel = new CompoundPropertyModel<PropertySettings>(property);

Form<PropertySettings> form = new Form<PropertySettings>("editPropertyForm", formModel)
{
    @Override
    protected void onSubmit()
    {
        PropertySettings propertySettings = this.getModelObject();
        ...         
    }
};

form.add(createEnumSelectbox(multivalueTypeDao, new PropertyModel<MultivalueType>(property, "multivalueType"), "multivalueType", true));

add(form);

创建选择框

protected DropDownChoice<MultivalueType> createEnumSelectbox(DaoForEntityWithSurrogateKey<MultivalueType> dao, IModel<MultivalueType> model, String componentName, boolean required)
{
    // create the model
    IModel<List<MultivalueType>> choices = createModelForListView(dao);

    // prepare the select-box renderer
    ChoiceRenderer<MultivalueType> renderer = new ChoiceRenderer<MultivalueType>("label", "id");

    // create the select-box component
    DropDownChoice<MultivalueType> selectBox = new DropDownChoice<MultivalueType>
    (
        componentName,
        model,
        choices,
        renderer
    );

    // mark the select-box as a required form field
    selectBox.setRequired(required);

    return selectBox;
}

protected IModel<List<MultivalueType>> createModelForListView(final DaoForEntityWithSurrogateKey<MultivalueType> dao)
{
    return new LoadableDetachableModel<List<MultivalueType>>() 
    {
        @Override
        protected List<BO> load() 
        {
            return dao.loadAll();
        }
     };
}

请注意,我将默认的MultivalueType实例(冗余地)设置为Form组件的CompundPropertyModel,并直接设置为DropDownChoice组件的模型.根据我在互联网上找到的内容,这应该足以让选择框在页面加载时预先选择相应的值,但它不起作用.

我已经验证了Form组件中的属性变量(从DAO获得)确实包含有效数据.

另请注意,一切正常但是对于预选 - 我在表单的onSubmit方法中正确填充了propertySettings变量.

Answer 1

我终于设法找到了问题.

我意识到当我显示表单时,Wicket会记录以下警告:

Model returned object ... which is not available in the list of selected objects.

基于该错误信息,我发现了,为了为默认选项的预选工作,业务实体必须覆盖equals方法(参见相应的JIRA票).至少在我正在使用的Wicket 1.5.4版本中.

希望这能帮助那些陷入同样问题的人!