Column converters as well as validators can be provided via client plugins. See Creating Client Plugins for more information on how to create client plugins.

Column Converters

In order to build a column converter, you need the plugin class implementing the IClientPlugin interface (see Implement the Plugin Interface) also needs to implement the interface IColumnConverterProvider to produce ITypedColumnConverter instances in the getColumnConverters() method. See API docs.

An ITypedColumnConverter has 3 methodsA column converter class implementing the ITypedColumnConverter interface has to implement the following three methods that will be displayed in the Conversion tab:

• convertFromObject()
  Converts from dataprovider value to db value

• convertToObject()
  Converts from db value to dataprovider value

• getToObjectType()
  The dataprovider data type (so the resulting type of the convertToObject(one of TEXT)), being one of the IColumnTypes constants: TEXT, INTEGER, NUMBER, DATETIME or MEDIA

A column converter class can define properties in the getDefaultProperties()

...

method, which will be displayed in the Conversion tab as well.

The column types that the column converter supports are to be specified in the getSupportedColumnTypes() method.

For an example of a column converter, see the NrToJodaConverter class in the example given on Providing UI Converters from plugins pagePlugins page.

All the implemented custom column converters must be returned by the getColumnConverters() method of the plugin class implementing the IColumnConverterProvider interface, so that they become available within Servoy Developer.

Column Validators

In order to build a column validator, you need the plugin class implementing the IClientPlugin interface (see Implement the Plugin Interface) also needs to implement the interface IColumnValidatorProvider to produce IColumnValidator instances in the getColumnValidators() method. See API docs.

The validation rule of an IColumnValidator is defined in the validate() method.

An IColumnValidator can also define properties in the getDefaultProperties() method, whose values will be set by the developer in UI, in the Validation tab.

The column types that the validator supports are specified in the getSupportedColumnTypes() method.

All the implemented custom column validators must be returned by the getColumnValidators() method of the plugin class implementing the IColumnValidatorProvider interface, so that they become available within Servoy Developer.

Example

This is an example of validating the value size of a column of type TEXT or MEDIA. The validation rule is that the value size must be lower or equal to the value given by the developer by setting the length property in the Validation tab.

public class SizeValidator implements IColumnValidator
{
	private static final String
	LENGTH_PROPERTY = "length";

	public Map getDefaultProperties()
	{
		Map props = new HashMap();
		props.put(LENGTH_PROPERTY, "");
		return props;
	}

	public String getName()
   		{
        	return "servoy.SizeValidator";
    	}
    
	public int[] getSupportedColumnTypes()
    	{
        	return new int[] { IColumnTypes.TEXT, IColumnTypes.MEDIA };
    	}

	public void validate(Map props, Object arg) throws IllegalArgumentException
	{
		String propLength = (String)props.get(LENGTH_PROPERTY);
		int length = new Double(propLength.replace(',', '.')).intValue();
		if (arg instanceof byte[] && ((byte[])arg).length > length)
		{
			throw new IllegalArgumentException();
		}
		else if (arg instanceof String && ((String)arg).length() > length)
		{
			throw new IllegalArgumentException();
		}
	}
}