Get the valuelist value that was DESELECTED

Classic Servoy
1

Hi All

Is it possible to discover the value from a checkbox based field that was unchecked?

I need to programatically add and remove valuelist items on an unrelated dataprovider - and need to know which checkbox was checked or unchecked at a given ondatachange point.

I know I can use oldValue and newValue, and compare lengths to see if data was added or removed, and then, compare values to work out what changed.

However I wonder if there might be a simpler (and less expensive) way to just get the value that was added, or the value that was removed, directly from the ondatachange method.

Any pointers would be appreciated.

2

For anyone interested, I worked out how to do this.

To discover which checkbox value was REMOVED:

if (oldValuesArray.length > newValuesArray.length){
	//we removed a value
	
	var removedValue = [];

	oldValuesArray.forEach(function(key) {
	    if (-1 === newValuesArray.indexOf(key)) {
	        removedValue.push(key);
	    }
	    });
	var vtheremovedvaluestring = removedValue.join('\n')

		
		var oldRemoveTagsArray = [];

	
		
	
			oldRemoveTagsArray = foundset.works_to_tags_join.all_tags.split('\n');
		
			
		var index = oldRemoveTagsArray.indexOf(vtheremovedvaluestring);
		if (index > -1) {
			oldRemoveTagsArray.splice(index, 1);
		}

		var myString = oldRemoveTagsArray.join('\n');
			
		foundset.works_to_tags_join.all_tags = myString
}

and to discover which was added:

if (oldValuesArray.length < newValuesArray.length){
	
	//we added a value
	
	var addedValue = [];

	newValuesArray.forEach(function(key) {

	    if (-1 === oldValuesArray.indexOf(key)) {
	    	addedValue.push(key);
	    }
	});

//	application.output(addedValue)
	
	
	
	var vtheaddedvaluestring = addedValue.join('\n')

	
	var oldAddTagsArray = [];
	
		oldAddTagsArray = foundset.works_to_tags_join.all_tags.split('\n');
	
	
	var index = oldAddTagsArray.indexOf(vtheaddedvaluestring);
	if (index < 0) {
		oldAddTagsArray.splice(2, 0, vtheaddedvaluestring);
	}

	var myString = oldAddTagsArray.join('\n');
		
	foundset.works_to_tags_join.all_tags = myString

	
//******************************
	
	
}

Only took two days…

3

Bevil!

We frequently have similar functionality and generally use this array difference function to get our results

/**
 * Returns the elements from the left array that are missing from the right array
 * @param {Array<*>} aLeft
 * @param {Array<*>} aRight
 * 
 * @return {Array<*>}
 *
 */
function difference(aLeft, aRight)
{
	if (!aLeft)	{
		return [];
	}
	
	if (!aRight) {
		return [].concat(aLeft);
	}
	
	var aDiff = aRight.filter(function (oVal) { return aLeft.indexOf(oVal) == -1 } );
	return aDiff;
}

So you end up with something like:

function onDataChange(event, newValue, oldValue) {
	
	var aNew = newValue.split('\n');
	var aOld = oldValue.split('\n');

	var aRemoved = scopes.array.difference(aOld, aNew);
	var aAdded = scopes.array.difference(aNew, aOld);

	//Do stuff

}