Fetching each row in composition(one to many)

Support
#1

can Anyone Suggest me how to fetch Composition(one to many) rows in a table?

I have two class called purchase request and purchase order.
purchase RequestLine entity is a Composition(one to many) in the purchase request.
purchase OrderLine entity is a composition(one to many) in Purchase Order.

I need to copy all the Composition values in purchase request Class to Purchase Order Class.

#2

Define a view and specify it when loading your entities using DataManager.

#3

Hi,

What I am trying to achieve is when I create a record in one class (purchase request) and click on the copy button, all of the record including the composition values should be copied to another class (purchaseOrder)

For your convenience, I am attaching the sample project which I am working on can u help me to access composition values with respect to that project.

Screenshot%20(10)Screenshot%20(12)Screenshot%20(11)Screenshot%20(13)Screenshot%20(14)

Code
package com.company.demopurchase.web.purchaserequest;

import com.company.demopurchase.entity.PurchaseOrder;

import com.company.demopurchase.entity.PurchaseRequest;
import com.company.demopurchase.entity.PurchaseRequestLine;
import com.haulmont.cuba.core.global.DataManager;
import com.haulmont.cuba.core.global.Metadata;
import com.haulmont.cuba.gui.components.AbstractLookup;
import com.haulmont.cuba.gui.data.CollectionDatasource;
import com.haulmont.cuba.gui.data.GroupDatasource;

import javax.inject.Inject;

import java.util.UUID;

public class PurchaseRequestBrowse extends AbstractLookup {

@Inject
private GroupDatasource<PurchaseRequest, UUID> purchaseRequestsDs;
@Inject
private Metadata metadata;
@Inject
private DataManager dataManager;
@Inject
private CollectionDatasource<PurchaseRequestLine, UUID> purchaseRequestLinesDs;




public void onButtonClick() {


    PurchaseRequest purchaseRequest = purchaseRequestsDs.getItem();


    if (purchaseRequest == null) {
        showMessageDialog("", "Select a Purchase Request", MessageType.CONFIRMATION);

    } else {
        PurchaseOrder gl = metadata.create(PurchaseOrder.class);

        gl.setDate(purchaseRequest.getDate());
        gl.setName(purchaseRequest.getName());





        dataManager.commit(gl);
    }

}

}

Thank you so much