When I have a list of validation classes implementing an interface injected into a service for validating a request Object , what kind o pattern is this if I iterate over this list and call the method validate of each one? All the validation classes validate something
Is some kind of chain pattern?
Thanks
No. Assuming you have a class Council
#Service
public class Council {
#Inject
private Councillor[] council;
public boolean getConsensus(Act purpose) {
for(Councillor member: council) {
if (member.vetoes(purpose)) {
return false;
}
}
return true;
}
}
This is not a chained because the elements have no responsibility for their chained neighbour. Here you have a stacktrace that returns to the very-same execution of the method getConsensus after every veto-call in a loop.
But an chain-pattern delegate the execution from Councillor to Councillor and let the stacktrace grow, one trace-line for every Councillor. If you have 200 Councillors your stacktrace will be 200 traces larger.
Related
We use Prettyfaces and Rewrite library in our JSF project.
Is there a way how we can reset bean attributes (set them to null) before PrettyFaces sets these attributes' values from query parameters in the URL?
I.e. can we call a method on the bean before PrettyFaces sets the values?
To accomplish this, I believe the simplest way would be to Inject the Bean into a RewriteConfiguration object. You'll need to make sure the priority is overridden such that this provider occurs before the built-in PrettyFaces functionality (I believe -10 should do, but you may need to play with this value):
public class ExampleConfigurationProvider extends HttpConfigurationProvider
{
#Inject
private MySessionBean bean;
#Override
public int priority()
{
return -10;
}
#Override
public Configuration getConfiguration(final ServletContext context)
{
return ConfigurationBuilder.begin()
.addRule()
.when(Path.matches("/my-path").and(Direction.isInbound()))
.perform(new HttpOperation() {
#Override
public void performHttp(HttpServletRewrite event, EvaluationContext context)
{
bean.clearValues();
}
});
}
}
```
Note, the .when() rule can contain any conditions that you want.
There are probably other ways of doing this, but this is the simplest I could think of.
I've created and deployed a plugin for the Update event of a custom entity but it seems when multiple users update different entities within quick succession the plugin uses the first entity it receives for each call.
To investigate further I added NLog via NuGet and at the beginning of the Execute function I generate a Guid and log the entity Id and the Guid. When I look in the log I can see the same ID and Guid logged 3-4 times before both change.
What I think is happening is the code is being run for each user but using the first entities details, applying only to the first entity.
Why is this happening and how can I stop it? The problem is users are saying the plugin is erratic.
Here is my code:
public class OnUpdateClaimSection : IPlugin
{
private static Logger logger = LogManager.GetCurrentClassLogger();
private string logId = Guid.NewGuid().ToString();
public void Execute(IServiceProvider serviceProvider)
{
try
{
IPluginExecutionContext context = (IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext));
IOrganizationServiceFactory serviceFactory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
IOrganizationService service = serviceFactory.CreateOrganizationService(context.UserId);
if (context.InputParameters.Contains("Target") && context.InputParameters["Target"] is Entity)
{
logger.Debug("{0} {1}|{2}|{3}", logId, context.MessageName, context.PrimaryEntityName, Common.GetSystemUserFullName(service, context.UserId));
var entity = context.InputParameters["Target"] as Entity;
logger.Debug("{0} {1}", logId, entity.Id);
var claimSection = GetClaimSection(service, entity.ToEntity<ClaimSection>());
CalculateClaimTotals(service, claimSection);
}
}
catch (Exception ex)
{
logger.Error("{0} Exception : {1}", logId, ex.Message);
throw;
}
}
}
Plugin classes are instantiated once by the CRM platform and are then reused for requests. Therefore you must be very careful when using class field variables, because they are not guaranteed to be thread-safe.
In your example field logId is modified in the Execute method. Race conditions of multiple threads are causing the effects you describe.
I suggest to only use plugin class fields when you have made sure that their implementation is absolutely thread-safe.
I have a problem. I'm learning JPA. I'm using embedded OpenEJB container in unit tests, but only working is #OneToMany(fetch=EAGER). Otherwise is the collection allways null. I haven't found, how the lazy strategy works, how the container fills the data and in which circumstances triggers the container the loading action?
I have read, that the action triggers when the getter is being called. But when I have the code:
#OneToMany(fetch = LAZY, mappedBy="someField")
private Set<AnotherEntities> entities = new Set<AnotherEntities>();
...
public Set<AnotherEntities> getEntities() {
return entities;
}
I'm always getting null. I thing, the LAZY strategy cannot be tested with embedded container. The problem might be also in the bidirectional relation.
Does have anybody else similar expiriences with the JPA testing?
Attachments
The real test case with setup:
#RunWith(UnitilsJUnit4TestClassRunner.class)
#DataSet("dataSource.xml")
public class UnitilsCheck extends UnitilsJUnit4 {
private Persister prs;
public UnitilsCheck() {
Throwable err = null;
try {
Class.forName("org.hsqldb.jdbcDriver").newInstance();
Properties props = new Properties();
props.setProperty(Context.INITIAL_CONTEXT_FACTORY, "org.apache.openejb.client.LocalInitialContextFactory");
props.put("ds", "new://Resource?type=DataSource");
props.put("ds.JdbcDriver", "org.hsqldb.jdbcDriver");
props.put("ds.JdbcUrl", "jdbc:hsqldb:mem:PhoneBookDB");
props.put("ds.UserName", "sa");
props.put("ds.Password", "");
props.put("ds.JtaManaged", "true");
Context context = new InitialContext(props);
prs = (Persister) context.lookup("PersisterImplRemote");
}
catch (Throwable e) {
e.printStackTrace();
err = e;
}
TestCase.assertNull(err);
}
#Test
public void obtainNickNamesLazily() {
TestCase.assertNotNull(prs);
PersistableObject po = prs.findByPrimaryKey("Ferenc");
TestCase.assertNotNull(po);
Collection<NickNames> nicks = po.getNickNames();
TestCase.assertNotNull(nicks);
TestCase.assertEquals("[Nick name: Kutyafája, belongs to Ferenc]", nicks.toString());
}
}
The bean Presister is the bean mediating access to the entity beans. The crucial code of class follows:
#PersistenceUnit(unitName="PhonePU")
protected EntityManagerFactory emf;
public PhoneBook findByPrimaryKey(String name) {
EntityManager em = emf.createEntityManager();
PhoneBook phonebook = (PhoneBook)em.find(PhoneBook.class, name);
em.close();
return phonebook;
}
Entity PhoneBook is one line of phone book (also person). One person can have zero or more nick names. With EAGER strategy it works. With LAZY the collection is allways null. May be the problem is in the detaching of objects. (See OpenEJB - JPA Concepts, part Caches and detaching.) But in the manual is written, that the collection can be sometimes (more like manytimes) empty, but not null.
The problem is in the life cycle of an entity. (Geronimo uses OpenJPA, so le't see OpenJPA tutorial, part Entity Lifecycle Management.) The application uses container managed transactions. Each method call on the bean Persiser runs in an own transation. And the persistency context depends on the transaction. The entity is disconnected from its context at the end of the transaction, thus at the end of the method. I tried to get the entity and on second line in the same method to get the collection of nick names and it worked. So the problem was identifyed: I cannot get additionally any entity data from the data store without re-attaching the entity to some persistency context. The entity is re-attached by the EntityManager.merge() method.
The code needs more correctures. Because the entity cannot obtain the EntityManager reference and re-attach itself, the method returning nick names must be moved to the Persister class. (The comment Heureka marks the critical line re-attaching the entity.)
public Collection<NickNames> getNickNamesFor(PhoneBook pb) {
//emf is an EntityManagerFactory reference
EntityManager em = emf.createEntityManager();
PhoneBook pb = em.merge(pb); //Heureka!
Collection<NickNames> nicks = pb.getNickNames();
em.close();
return nicks;
}
The collection is then obtained in this way:
//I have a PhoneBook instance pb
//pb.getNickNames() returns null only
//I have a Persister instance pe
nicks = pe.getNickNames(pb);
That's all.
You can have a look at my second question concerning this topic I'have asked on this forum. It is the qustion OpenJPA - lazy fetching does not work.
How I would write the code
#Entity
public class MyEntity {
#OneToMany(fetch = LAZY, mappedBy="someField")
private Set<AnotherEntities> entities;
// Constructor for JPA
// Fields aren't initalized here so that each em.load
// won't create unnecessary objects
private MyEntity() {}
// Factory method for the rest
// Have field initialization with default values here
public static MyEntity create() {
MyEntity e = new MyEntity();
e.entities = new Set<AnotherEntities>();
return e;
}
public Set<AnotherEntities> getEntities() {
return entities;
}
}
Idea no 2:
I just thought that the order of operations in EAGER and LAZY fetching may differ i.e. EAGER fetching may
Declare field entities
Fetch value for entities (I'd assume null)
Set value of entities to new Set<T>()
while LAZY may
Declare field `entities
set value of entities to new Set<T>()
Fetch value for entities (I'd assume null)'
Have to find a citation for this as well.
Idea no 1: (Not the right answer)
What if you'd annotate the getter instead of the field? This should instruct JPA to use getters and setters instead of field access.
In the Java Persistence API, an entity can have field-based or
property-based access. In field-based access, the persistence provider
accesses the state of the entity directly through its instance
variables. In property-based access, the persistence provider uses
JavaBeans-style get/set accessor methods to access the entity's
persistent properties.
From The Java Persistence API - A Simpler Programming Model for Entity Persistence
I'm currently working on a multi-tenant application that employs Shared DB/Shared Schema approach. IOW, we enforce tenant data segregation by defining a TenantID column on all tables. By convention, all SQL reads/writes must include a Where TenantID = '?' clause. Not an ideal solution, but hindsight is 20/20.
Anyway, since virtually every page/workflow in our app must display tenant specific data, I made the (poor) decision at the project's outset to employ a Singleton to encapsulate the current user credentials (i.e. TenantID and UserID). My thinking at the time was that I didn't want to add a TenantID parameter to each and every method signature in my Data layer.
Here's what the basic pseudo-code looks like:
public class UserIdentity
{
public UserIdentity(int tenantID, int userID)
{
TenantID = tenantID;
UserID = userID;
}
public int TenantID { get; private set; }
public int UserID { get; private set; }
}
public class AuthenticationModule : IHttpModule
{
public void Init(HttpApplication context)
{
context.AuthenticateRequest +=
new EventHandler(context_AuthenticateRequest);
}
private void context_AuthenticateRequest(object sender, EventArgs e)
{
var userIdentity = _authenticationService.AuthenticateUser(sender);
if (userIdentity == null)
{
//authentication failed, so redirect to login page, etc
}
else
{
//put the userIdentity into the HttpContext object so that
//its only valid for the lifetime of a single request
HttpContext.Current.Items["UserIdentity"] = userIdentity;
}
}
}
public static class CurrentUser
{
public static UserIdentity Instance
{
get { return HttpContext.Current.Items["UserIdentity"]; }
}
}
public class WidgetRepository: IWidgetRepository{
public IEnumerable<Widget> ListWidgets(){
var tenantId = CurrentUser.Instance.TenantID;
//call sproc with tenantId parameter
}
}
As you can see, there are several code smells here. This is a singleton, so it's already not unit test friendly. On top of that you have a very tight-coupling between CurrentUser and the HttpContext object. By extension, this also means that I have a reference to System.Web in my Data layer (shudder).
I want to pay down some technical debt this sprint by getting rid of this singleton for the reasons mentioned above. I have a few thoughts on what a better implementation might be, but if anyone has any guidance or lessons learned they could share, I would be much obliged.
CurrentUser isn't quite a singleton. I'm not exactly sure what you'd call it. (A singleton by definition can only exist one at a time, and any number of UserIdentity instances can be created at will by outside code and coexist without any issues.)
Personally, i'd take CurrentUser.Instance and either move it to UserIdentity.CurrentUser, or put it together with whatever similar "get the global instance" methods and properties you have. Gets rid of the CurrentUser class, at least. While you're at it, make the property settable at the same place -- it's already settable, just in an way that (1) would look like magic if the two classes weren't shown right next to each other, and (2) makes changing how the current user identity is set later harder.
Doesn't get rid of the global, but you're not really gonna get around that without passing the UserIdentity to every function that needs it.
I'm starting to learn how to use PHPUnit to test the website I'm working on. The problem I'm running into is that I have five different user types defined and I need to be able to test every class with the different types. I currently have a user class and I would like to pass this to each function but I can't figure out how to pass this or test the different errors that could come back as being correct or not.
Edit: I should have said. I have a user class and I want to pass a different instance of this class to each unit test.
If your various user classes inherit from a parent user class, then I recommend you use the same inheritance structure for your test case classes.
Consider the following sample classes:
class User
{
public function commonFunctionality()
{
return 'Something';
}
public function modifiedFunctionality()
{
return 'One Thing';
}
}
class SpecialUser extends User
{
public function specialFunctionality()
{
return 'Nothing';
}
public function modifiedFunctionality()
{
return 'Another Thing';
}
}
You could do the following with your test case classes:
class Test_User extends PHPUnit_Framework_TestCase
{
public function create()
{
return new User();
}
public function testCommonFunctionality()
{
$user = $this->create();
$this->assertEquals('Something', $user->commonFunctionality);
}
public function testModifiedFunctionality()
{
$user = $this->create();
$this->assertEquals('One Thing', $user->commonFunctionality);
}
}
class Test_SpecialUser extends Test_User
{
public function create() {
return new SpecialUser();
}
public function testSpecialFunctionality()
{
$user = $this->create();
$this->assertEquals('Nothing', $user->commonFunctionality);
}
public function testModifiedFunctionality()
{
$user = $this->create();
$this->assertEquals('Another Thing', $user->commonFunctionality);
}
}
Because each test depends on a create method which you can override, and because the test methods are inherited from the parent test class, all tests for the parent class will be run against the child class, unless you override them to change the expected behavior.
This has worked great in my limited experience.
If you're looking to test the actual UI, you could try using something like Selenium (www.openqa.org). It lets you write the code in PHP (which I'm assuming would work with phpUnit) to drive the browser..
Another approach would be to have a common method that could be called by each test for your different user type. ie, something like 'ValidatePage', which you could then call from TestAdminUser or TestRegularUser and have the method simply perform the same basic validation of what you're expecting..
Just make sure you're not running into an anti-pattern here. Maybe you do too much work in the constructor? Or maybe these should be in fact different classes? Tests often give you clues about design of code. Listen to them.