au.com.cybersearch2.example

Class ManyToManyMain

java.lang.Object

au.com.cybersearch2.example.ManyToManyMain

Direct Known Subclasses:

H2ManyToManyMain

public class ManyToManyMain
extends Object

ORIGINAL COMMENTS: Main sample routine to show how to do many-to-many type relationships. It also demonstrates how we user inner queries as well foreign objects.

NOTE: We use asserts in a couple of places to verify the results but if this were actual production code, we would have proper error handling.

CLASSYTOOLS COMMENTS:

This example shows JPA in action. The application code exempifies use of a standard persistence interface. The OrmLite implemention is mostly hidden in library code, but does show up in named queries where, to keep things lightweight, OrmLite QueryBuilder is employed in place of a JQL implementation @see ManyToManyGenerator.

Also noteable is dependency injection using Dagger @see ManyToManyModule. If one studies the details, what the dependency inject allows is flexibility in 3 ways:

1. Choice of database - the PersistenceContext binding
2. Location of resource files such as persistence.xml (and Locale too) - the ResourceEnvironment binding
3. How to reduce background thread priority - the ThreadHelper binding

Field Summary

Fields

Modifier and Type	Field and Description
static String	POSTS_BY_USER Named query to find all posts staged by a user identified by ID
static String	PU_NAME Persistence Unit name to look up configuration details in persistence.xml
static String	USERS_BY_POST Named query to find all users associated with a post identified by ID

Constructor Summary

Constructors

Constructor and Description
ManyToManyMain() Create ManyToManyMain object This creates and populates the database using JPA, provides verification logic and runs a test from main().

Method Summary

Methods

Modifier and Type	Method and Description
Post	getPost1() Returns "Wow is it cold outside!" Post
Post	getPost2() Returns "Now it's a bit warmer thank goodness." Post
User	getUser1() Returns Bilbo Baggins' User
User	getUser2() Returns Gandalf Gray's User
static void	main(String[] args) Test ManyToMany association
void	setUp() Populate entity tables.
void	verifyPostsByUser(List<Post> posts) Verify posts retrieved by "posts_by_user" named query
void	verifyUsersByPost(List<User> usersByPost1, List<User> usersByPost2) Verify users retrieved by "users_by_post" named query

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

POSTS_BY_USER

public static final String POSTS_BY_USER

Named query to find all posts staged by a user identified by ID

See Also:

Constant Field Values

USERS_BY_POST

public static final String USERS_BY_POST

Named query to find all users associated with a post identified by ID

See Also:

Constant Field Values

PU_NAME

public static final String PU_NAME

Persistence Unit name to look up configuration details in persistence.xml

See Also:

Constant Field Values

Constructor Detail

ManyToManyMain

public ManyToManyMain()

Create ManyToManyMain object This creates and populates the database using JPA, provides verification logic and runs a test from main().

Method Detail

main

public static void main(String[] args)

Test ManyToMany association

Parameters:

args - Not used

setUp

public void setUp()
           throws InterruptedException

Populate entity tables. Call this before doing any queries. Note the calling thread is suspended while the work is performed on a background thread.

Throws:

InterruptedException

getUser1

public User getUser1()

Returns Bilbo Baggins' User

Returns:

User

getUser2

public User getUser2()

Returns Gandalf Gray's User

Returns:

User

getPost1

public Post getPost1()

Returns "Wow is it cold outside!" Post

Returns:

Post

getPost2

public Post getPost2()

Returns "Now it's a bit warmer thank goodness." Post

Returns:

Post

verifyPostsByUser

public void verifyPostsByUser(List<Post> posts)

Verify posts retrieved by "posts_by_user" named query

Parameters:

posts - List<Post> retrieved for user1

verifyUsersByPost

public void verifyUsersByPost(List<User> usersByPost1,
                     List<User> usersByPost2)

Verify users retrieved by "users_by_post" named query

Parameters:

usersByPost1 - List<User> retrieved for post1

usersByPost2 - List<User> retrieved for post2