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4.3. Mapping Java and AS3 objects

data conversions are done during serialization/deserialization

Bi-directional Many to Many

object model can choose if it will be mapped in both directions

in which direction it will be mapped

Data Management

Tide provides an integration between the Flex/LCDS concept of managed entities and the server persistence context (JPA or Hibernate)

Tide maintains a client-side cache of entity instances and ensures that every instance is unique in the Flex client context

CDI + JPA + EJB + JTA + JSF: Login quickstart

displayed using JSF views, business logic is encapsulated in CDI beans, information is persisted using JPA, and transactions can be controlled manually or using EJB

Deploying the Login example using Eclipse

best strategies for implementation of equals() and hashcode() in your persistent classes

The general contract is: if you want to store an object in a List, Map or a Set then it is an requirement that equals and hashCode are implemented so they obey the standard contract as specified in the  documentation

Why are equals() and hashcode() importantNormally, most Java objects provide a built-in equals() and hashCode() based on the object's identity; so each new() object will be different from all others.

Result Set Mapping

When a native SQL query returns objects, the SQL must ensure it returns the correct data to build the resultClass using the correct column names as specified in the mappings. If the SQL is more complex and returns different column names, or returns data for multiple objects then a @SqlResultSetMapping must be used.

@NamedNativeQuery

Mapping enum to database column using JPA/Hibernate You can use any of the 3 approaches discussed above. Map the enum to an integer column. The persistence implementation should automatically convert enum to ordinal() and back for you. Map the enum to a String column. The persistence implementation should automatically convert the enum value to String value via the name() function. Map the enum using a business value. You should mark the enum field as @Transient, and create another String field which you can map to a String column in your database table. Here’s an example code snippet. view plaincopy to clipboardprint?@Entity  public class Product {   @Column   private String colorValue;     @Transient   public Color getColor() {    return Color.fromValue(colorValue);   }     public void setColor(Color color) {    this.colorValue = color.toValue();   }  }  

Approach 3: Using a user defined business value – Recommended approach! This approach involves assigning a an explicit user defined value to each enum constant and defining a toValue() and fromValue() methods on the enum to do the serialization and deserialization.

public enum Color {   RED("RED"), GREEN("GREEN"), BLUE("BLUE"), UNKNOWN("UNKNOWN");     private final String value;     Color(String value) {     this.value = value;   }     public static Color fromValue(String value) {     if (value != null) {       for (Color color : values()) {         if (color.value.equals(value)) {           return color;         }       }     }       // you may return a default value     return getDefault();     // or throw an exception     // throw new IllegalArgumentException("Invalid color: " + value);   }     public String toValue() {     return value;   }     public static Color getDefault() {     return UNKNOWN;   }  }  public enum Color { RED("RED"), GREEN("GREEN"), BLUE("BLUE"), UNKNOWN("UNKNOWN"); private final String value; Color(String value) { this.value = value; } public static Color fromValue(String value) { if (value != null) { for (Color color : values()) { if (color.value.equals(value)) { return color; } } } // you may return a default value return getDefault(); // or throw an exception // throw new IllegalArgumentException("Invalid color: " + value); } public String toValue() { return value; } public static Color getDefault() { return UNKNOWN; } } This approach is better than approach 1 and approach 2 above. It neither depends on the order in which the enum constants are declared nor on the constant names.

3 primary concepts:

Session Management Cheat Sheet

should not be extremely descriptive nor offer unnecessary details

change the default session ID name of the web development framework to a generic name

AnemicDomainModel

Eric Evans

basic symptom of an Anemic Domain Model