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Contributing UI Converters

A UI converter can be contributed by a Java Servoy client plugin.

To do this, the plugin class implementing the IClientPlugin (see Implement the plugin interface) must also implement interface IUIConverterProvider to produce IUIConverter instances in the getUIConverters() method, see api docs.

An IUIConverter converter has 3 methods:

  • convertFromObject()
    Convert from UI value to dataprovider value
  • convertToObject()
    Converts from dataprovider value to UI value
  • type (one of TEXT, INTEGER, NUMBER, DATETIME or MEDIA)
    The UI data type (so the resulting type of the convertToObject()).

The implemented UI converters returned by the getUIConverters() method of the plugin class implementing the IUIConverterProvider interface, will be then checked by the plugin manager which will add them to the list of Servoy UI converters.

Example

This is an example of a plugin that delivers a converter from joda time (which has support for time persiods) to java-util-date (which is supported by Servoy UI elements) time.

private static final IUIConverter[] UI_CONVERTERS = new IUIConverter[] { JodaToDateConverter.INSTANCE };
 
public IUIConverter[] getUIConverters()
{
    return UI_CONVERTERS;
}
 
static class NrToJodaConverter implements ITypedColumnConverter
{
    static final NrToJodaConverter INSTANCE = new NrToJodaConverter();
 
    public Object convertToObject(Map<String, String> props, int column_type, Object dbvalue) throws Exception
    {
        if (dbvalue == null)
        {
            return null;
        }
        return new DateTime(Utils.getAsLong(dbvalue));
    }
 
    public Object convertFromObject(Map<String, String> props, int column_type, Object obj) throws Exception
    {
        if (obj instanceof DateTime)
        {
            return Long.valueOf(((DateTime)obj).getMillis());
        }
        return obj; // or throw an exception
    }
 
    public Map<String, String> getDefaultProperties()
    {
        return null;
    }
 
    public int[] getSupportedColumnTypes()
    {
        return new int[] { IColumnTypes.INTEGER };
    }
 
    public String getName()
    {
        return getClass().getSimpleName();
    }
 
    public int getToObjectType(Map<String, String> props)
    {
        // Servoy does not understand joda time natively.
        return IColumnTypes.MEDIA;
    }
}
 
static class JodaToDateConverter implements IUIConverter
{
    static final JodaToDateConverter INSTANCE = new JodaToDateConverter();
 
    public Object convertFromObject(Map<String, String> props, int input_type, Object converted) throws Exception
    {
        if (converted instanceof Date)
        {
            return new DateTime(((Date)converted).getTime());
        }
        return converted; // or return null or throw an exception
    }
 
    public Object convertToObject(Map<String, String> props, int input_type, Object input) throws Exception
    {
        if (input instanceof DateTime)
        {
            return new Date(((DateTime)input).getMillis());
        }
        return input; // or return null or throw an exception
    }
 
    public Map<String, String> getDefaultProperties()
    {
        return null;
    }
 
    public int[] getSupportedDataproviderTypes()
    {
        // Servoy does not understand joda time natively, therefore the dataprovider type will be MEDIA.
        return new int[] { IColumnTypes.MEDIA };
    }
 
    public String getName()
    {
        return getClass().getSimpleName();
    }
 
    public int getToObjectType(Map<String, String> props)
    {
        return IColumnTypes.DATETIME;
    }
}
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