iReport : How to process a parameter whose expression class = List and inside that list is another list?

问题

I have a parameter whose expression class is a List. Inside that List is another list so the data looks something like this.

Class Bean{

String property1
String property2
Long property3
List<BeanDetails> beanDetails
}

Please take note that I'll be passing Bean in a list. (List beans)

1) Is it possible to process and read this type of data in iReport?

2) How are we going to declare it/ define it and use it in iReport?

The report should look like this

Col1    Col2     Col3       Col4              Col5              Col6    
 1     bean.id  bean.name   beanDetail.det1   beanDetail.det2   beanDetail.det3
                            beanDetail.det1   beanDetail.det2   beanDetail.det3
                            beanDetail.det1   beanDetail.det2   beanDetail.det3

 2     bean.id  bean.name   beanDetail.det1   beanDetail.det2   beanDetail.det3
                            beanDetail.det1   beanDetail.det2   beanDetail.det3
                            beanDetail.det1   beanDetail.det2   beanDetail.det3

回答1:

There are multiple solutions to achieve what you need.

Create flat structure of your datasource, as example a List of Map<String,Object>, looping your Bean, BeanDetails example

List<Map<String,Object>> mapList = new ArrayList<Map<String,Object>>();
for(Bean bean : yourBeans){
  Map<String,Object> map = new HashMap<String,Object>();
  map.put("col1", bean.getProperty1());
  map.put("col2", bean.getProperty2());
  map.put("col3", bean.getProperty3());
  boolean first = true;
  if (bean.getBeanDetails()==null|| bean.getBeanDetails().size()==0){
    mapList.add(map);
  }else{
   for (BeanDetails bd:bean.getBeanDetails()){
     if (!first){
         map = new HashMap<String,Object>();
         map."col1", "");//or use printWhenExpression != null in jrxml
         ....
     }else{
        first = false;
     }
     map.put("col4",bd.getDet1());
     ....
     mapList.add(map);
  }
 }
}
//This now becomes your datasource
JRMapArrayDataSource datasource = new JRMapArrayDataSource(mapList);

Use subreport include a subreport spanning col4 to col6, setup field Bean in main report

<field name="_THIS" class="com.your.package.Bean"/>

and pass as datasource to the subreport

<dataSourceExpression><![CDATA[new net.sf.jasperreports.engine.data.JRBeanCollectionDataSource($F{_THIS}.getBeanDetails())]]></dataSourceExpression>

Create you own JRDataSource (I will not submit the whole class, but only some hints on how this can be done, creating a new class implementing JRDataSource)

JRDataSource myDatasource = new JRDataSource() {
    //TODO: keep controll of you list of Beans, current Bean and current BeanDetails, using pointers.
    @Override
    public boolean next() throws JRException {
     //TODO: Implement if there are still records, move to next Bean or BeanDetails
     boolean existsRecords = false;
     return existsRecords;
    }

    @Override
    public Object getFieldValue(JRField field) throws JRException {
       String name = field.getName();
       //TODO: On the basis of your pointer, current Bean and current BeanDetails, return the value requested.
       return null;
    }
};

Make your choice and have fun!

来源：https://stackoverflow.com/questions/34125526/ireport-how-to-process-a-parameter-whose-expression-class-list-and-inside-th

标签

parameters

jasper-reports