List distinct values of another table field in a combo box.

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Article ID: KB0073981

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Updated On:

Products	Versions
TIBCO EBX	All supported versions.

Description

In this article we will give an example of constraint that will list distinct values of another table field in a dropdown.

To achieve this we implemented a programmatic enumeration ConstraintEnumeration.

Resolution

Implementation

In our example we want to display distinct values of field "val" of table 1 in an "enum" field of table 2.

getValues method implementation:

public List<String> getValues(ValueContext context) throws InvalidSchemaException {

List<String> list = new ArrayList<String>();

Adaptation dataset = context.getAdaptationInstance(); // retrieve dataset
AdaptationTable table1 = dataset.getTable(Path.parse("/root/table1")); //retrieve table1

RequestSortCriteria criteria = new RequestSortCriteria();
criteria.add(Path.parse("./val"));

RequestResult result = table1.createRequestResult(null, criteria); // create a request on table1 and sort it by 'val' field

Adaptation currentRecord = result.nextAdaptation();
String currentValue = null;
String previousValue = null;

while (currentRecord != null){ // go through the request result

currentValue = currentRecord.getString(Path.parse("./val")); // get the current value

if (currentValue != previousValue){

list.add(currentValue); // we add it to the list if it is different from the previous value
}
previousValue = currentValue;
currentRecord = result.nextAdaptation();
}

return list;
}