ObjectQuery tutorial - step 4

The following step shows how to create an ObjectGrid with four maps and a schema for the maps. Some of the maps maintain a one-to-one (unidirectional) and one-to-many (bidirectional) relationship. After creating the maps, you can then run the sample Application.java program to insert objects into the cache and run queries to retrieve these objects.

Before you begin

Be sure to have completed ObjectQuery tutorial - step 3 prior to continuing with the current step.

About this task

You are required to create four JAVA classes. These are the maps for the ObjectGrid:

• OrderBean.java
• OrderLineBean.java
• CustomerBean.java
• ItemBean.java

After creating these JAVA classes with these relationships, you can then run the sample Application.java program. This program lets you insert objects into the cache and retrieve these using several queries.

1. Create the following JAVA classes:

   OrderBean.java
   
   
   public class OrderBean implements Serializable {
      String orderNumber;
      java.util.Date date;
      String customerId;
      String itemName;
      List<Integer> orderLines;
   }
       

   OrderLineBean.java
   
   public class OrderLineBean implements Serializable {
   	 int lineNumber;
   	 int quantity;
   	 String orderNumber;
   	 String itemId;
   }

   CustomerBean.java
   
   public class CustomerBean implements Serializable{
     String id;
     String firstName;
     String surname;
     String address;
     String phoneNumber;
   }
   

   ItemBean.java
   
   public class ItemBean implements Serializable {
   	 String id; 	
   	 String description; 	
   	 long quantityOnHand; 	
   	 double price;
   }

2. After creating the classes, you can run the sample Application.java:

   Application.java
   
   
   		public class Application static public void main(String [] args)throws Exception
           // Configure programatically
    				objectGrid og = ObjectGridManagerFactory.getObjectGridManager().createObjectGrid();
           og.defineMap("Order");
           og.defineMap("Customer");
           og.defineMap("OrderLine");
           og.defineMap("Item");
   
           // Define the schema
           QueryConfig queryCfg = new QueryConfig();
           queryCfg.addQueryMapping(new QueryMapping("Order", OrderBean.class.getName(), "orderNumber", QueryMapping.FIELD_ACCESS));
           queryCfg.addQueryMapping(new QueryMapping("Customer", CustomerBean.class.getName(), "id", QueryMapping.FIELD_ACCESS));
           queryCfg.addQueryMapping(new QueryMapping("OrderLine", OrderLineBean.class.getName(), "lineNumber", QueryMapping.FIELD_ACCESS));
           queryCfg.addQueryMapping(new QueryMapping("Item", ItemBean.class.getName(), "id", QueryMapping.FIELD_ACCESS));
           queryCfg.addQueryRelationship(new QueryRelationship(OrderBean.class.getName(), CustomerBean.class.getName(), "customerId", null));
           queryCfg.addQueryRelationship(new QueryRelationship(OrderBean.class.getName(), OrderLineBean.class.getName(), 
   				"orderLines", "lineNumber"));
           queryCfg.addQueryRelationship(new QueryRelationship(OrderLineBean.class.getName(), ItemBean.class.getName(), "itemId", null));
           og.setQueryConfig(queryCfg);
   
           // Get session and maps;
           Session s = og.getSession();
           ObjectMap orderMap = s.getMap("Order");
           ObjectMap custMap = s.getMap("Customer");
           ObjectMap itemMap = s.getMap("Item");
           ObjectMap orderLineMap = s.getMap("OrderLine");
   
           // Add data 
           s.begin();
           CustomerBean aCustomer = new CustomerBean();
           aCustomer.address = "Main Street";
           aCustomer.firstName = "John";
           aCustomer.surname = "Smith";
           aCustomer.id = "C001";
           aCustomer.phoneNumber = "5555551212";
           custMap.insert(aCustomer.id, aCustomer);
   
           // Insert an order with a reference to the customer, but without any OrderLines yet.
           // Because we are using CopyMode.COPY_ON_READ_AND_COMMIT, the
           // insert won't be copied into the backing map until commit time, so
           // the reference is still good.
   				
   				OrderBean anOrder = new OrderBean();
   				anOrder.customerId = aCustomer.id;
   				anOrder.date = new java.util.Date();
   				anOrder.itemName = "Widget";
   				anOrder.orderNumber = "1";
   				anOrder.orderLines = new ArrayList();
   				orderMap.insert(anOrder.orderNumber, anOrder);
   				        
           ItemBean anItem = new ItemBean();
           anItem.id = "AC0001";
           anItem.description = "Description of widget";
           anItem.quantityOnHand = 100;
           anItem.price = 1000.0;
           itemMap.insert(anItem.id, anItem);
   
   				// Create the OrderLines and add the reference to the Order
           OrderLineBean anOrderLine = new OrderLineBean();
           anOrderLine.lineNumber = 99;
           anOrderLine.itemId = anItem.id;
           anOrderLine.orderNumber = anOrder.orderNumber;
           anOrderLine.quantity = 500;
           orderLineMap.insert(anOrderLine.lineNumber, anOrderLine);
           anOrder.orderLines.add(Integer.valueOf(anOrderLine.lineNumber));
   
   				anOrderLine = new OrderLineBean();
           anOrderLine.lineNumber = 100;
           anOrderLine.itemId = anItem.id;
           anOrderLine.orderNumber = anOrder.orderNumber;
           anOrderLine.quantity = 501;
           orderLineMap.insert(anOrderLine.lineNumber, anOrderLine);
           anOrder.orderLines.add(Integer.valueOf(anOrderLine.lineNumber));
           s.commit();
   
   				s.begin();
           // Find all customers who have ordered a specific item.
           ObjectQuery query = s.createObjectQuery("SELECT c FROM Order o JOIN o.customerId as c WHERE o.itemName='Widget'");
           Iterator result = query.getResultIterator();
           aCustomer = (CustomerBean) result.next();
           System.out.println("Found order for customer: " + aCustomer.firstName + " " + aCustomer.surname);
           s.commit();
   
   				s.begin();
           // Find all OrderLines for customer C001.
           // The query joins are expressed on the foreign keys.
           query = s.createObjectQuery("SELECT ol FROM Order o JOIN o.customerId as c JOIN o.orderLines as ol WHERE c.id='C001'");
           result = query.getResultIterator();
           System.out.println("Found OrderLines:");
           while(result.hasNext()) {
               anOrderLine = (OrderLineBean) result.next();
               System.out.println(anOrderLine.lineNumber + ", qty=" + anOrderLine.quantity);
           }
   	// Close the session (optional in Version 7.1.1 and later) for improved performance
   	s.close();   
    		}
   }
   

3. Using the XML configuration below (in the ObjectGrid deployment descriptor) is equivalent to the programmatic approach above.

   <?xml version="1.0" encoding="UTF-8"?><objectGridConfig xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://ibm.com/ws/objectgrid/config
   ../objectGrid.xsd"xmlns="http://ibm.com/ws/objectgrid/config">
   <objectGrids>
   	 <objectGrid name="CompanyGrid">
     <backingMap name="Order"/>
     <backingMap name="Customer"/>
     <backingMap name="OrderLine"/>
     <backingMap name="Item"/>
   
   <querySchema>
    <mapSchemas>
     <mapSchema
   		mapName="Order"
   		valueClass="com.mycompany.OrderBean"
   		primaryKeyField="orderNumber"
   		accessType="FIELD"/>
     <mapSchema
   		mapName="Customer"
   		valueClass="com.mycompany.CustomerBean"
   		primaryKeyField="id"
   		accessType="FIELD"/>
     <mapSchema
   		mapName="OrderLine"
   		valueClass="com.mycompany.OrderLineBean"
   		primaryKeyField="
   		lineNumber"
   		accessType="FIELD"/>
     <mapSchema
   		mapName="Item"
   		valueClass="com.mycompany.ItemBean"
   		primaryKeyField="id"
   		accessType="FIELD"/>
     </mapSchemas>
   
   <relationships>
   	<relationship
   		source="com.mycompany.OrderBean"
   		target="com.mycompany.CustomerBean"
   		relationField="customerId"/>
   	<relationship
   		source="com.mycompany.OrderBean"
   		target="com.mycompany.OrderLineBean"
   		relationField="orderLines"
   		invRelationField="lineNumber"/>
   	<relationship
   		source="com.mycompany.OrderLineBean"
   		target="com.mycompany.ItemBean"
   		relationField="itemId"/>
       </relationships>
      </querySchema>
     </objectGrid>
    </objectGrids>
   </objectGridConfig>