Cast string error in function groupConcat

Description: The first parameter type in function groupConcat is String. So if the column I need to use in function groupConcat is not string, I need to cast the column type to string. But there still throw an exception "Integer cannot cast to string" even I have already cast the column type to string.

Affected Product Version:

4.0.24

Steps to reproduce:

The code: `@App:name("GroupByApp") @App:description("Description of the plan")

-- Please refer to https://docs.wso2.com/display/SP400/Quick+Start+Guide on getting started with SP editor.

define stream inputstream (id string,weight int);

@sink(type='log', prefix='LOGGER') define stream OutputStream(id string,weight string);

@info(name='GroupbyQuery') from inputstream#window.timeBatch(10 second) select id,str:groupConcat(cast(weight,'string'),',',true) as weight group by id insert into OutputStream;`

The exeption: [2018-12-28_08-58-27_187] ERROR {org.wso2.siddhi.core.query.processor.stream.AbstractStreamProcessor} - Error on 'GroupByApp'. java.lang.Integer cannot be cast to java.lang.String Dropping event chunk EventChunk{first=StreamEvent{ timestamp=1545958697185, beforeWindowData=null, onAfterWindowData=[1], outputData=[1, null], type=CURRENT, next=null}}, error in processing org.wso2.siddhi.core.query.processor.stream.window.TimeBatchWindowProcessor. (Encoded) java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String at org.wso2.extension.siddhi.execution.string.GroupConcatFunctionExtension.processAdd(GroupConcatFunctionExtension.java:167) at org.wso2.siddhi.core.query.selector.attribute.aggregator.AttributeAggregator.process(AttributeAggregator.java:82) at org.wso2.siddhi.core.query.selector.attribute.processor.executor.GroupByAggregationAttributeExecutor.execute(GroupByAggregationAttributeExecutor.java:92) at org.wso2.siddhi.core.query.selector.attribute.processor.AttributeProcessor.process(AttributeProcessor.java:41) at org.wso2.siddhi.core.query.selector.QuerySelector.processInBatchGroupBy(QuerySelector.java:293) at org.wso2.siddhi.core.query.selector.QuerySelector.process(QuerySelector.java:84) at org.wso2.siddhi.core.query.processor.stream.window.TimeBatchWindowProcessor.process(TimeBatchWindowProcessor.java:254) at org.wso2.siddhi.core.query.processor.stream.window.WindowProcessor.processEventChunk(WindowProcessor.java:66) at org.wso2.siddhi.core.query.processor.stream.AbstractStreamProcessor.process(AbstractStreamProcessor.java:125) at org.wso2.siddhi.core.query.input.stream.single.EntryValveProcessor.process(EntryValveProcessor.java:50) at org.wso2.siddhi.core.util.Scheduler.sendTimerEvents(Scheduler.java:197) at org.wso2.siddhi.core.util.Scheduler$EventCaller.run(Scheduler.java:249) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745)

I have already found the code which occur the error. GroupConcatFunctionExtension.java

The code: ` @Override public Object processAdd(Object o) { addString((String) o); return constructConcatString(","); }

@Override
public Object processAdd(Object[] objects) {
    addString((String) objects[0]);
    return constructConcatString((String) objects[1]);
}

@Override
public Object processRemove(Object o) {
    removeString((String) o);
    return constructConcatString(",");
}

@Override
public Object processRemove(Object[] objects) {
    removeString((String) objects[0]);
    return constructConcatString((String) objects[1]);
}`

should be changed as below:

`@Override public Object processAdd(Object o) { addString(String.valueOf(o)); return constructConcatString(","); }

@Override
public Object processAdd(Object[] objects) {
    addString(String.valueOf(objects[0]));
    return constructConcatString(String.valueOf(objects[1]));
}

@Override
public Object processRemove(Object o) {
    removeString(String.valueOf(o));
    return constructConcatString(",");
}

@Override
public Object processRemove(Object[] objects) {
    removeString(String.valueOf(objects[0]));
    return constructConcatString(String.valueOf(objects[1]));
}`

siddhi-io / siddhi-execution-string

Cast string error in function groupConcat #43