We Keep Coding

#ConditionalOnProperty for lists or arrays?

I'm using Spring Boot 1.4.3 #AutoConfiguration where I create beans automatically based on properties user specifies. User can specify an array of services, where name and version are required fields:
service[0].name=myServiceA
service[0].version=1.0
service[1].name=myServiceB
service[1].version=1.2
...
If the user forgets to specify a required field on even just one service, I want to back-off and not create any beans. Can I accomplish this with #ConditionalOnProperty? I want something like:
#Configuration
#ConditionalOnProperty({"service[i].name", "service[i].version"})
class AutoConfigureServices {
....
}

This is the custom Condition I created. It needs some polishing to be more generic (ie not hardcoding strings), but worked great for me.
To use, I annotated my Configuration class with #Conditional(RequiredRepeatablePropertiesCondition.class)
public class RequiredRepeatablePropertiesCondition extends SpringBootCondition {
private static final Logger LOGGER = LoggerFactory.getLogger(RequiredRepeatablePropertiesCondition.class.getName());
public static final String[] REQUIRED_KEYS = {
"my.services[i].version",
"my.services[i].name"
};
#Override
public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
List<String> missingProperties = new ArrayList<>();
RelaxedPropertyResolver resolver = new RelaxedPropertyResolver(context.getEnvironment());
Map<String, Object> services = resolver.getSubProperties("my.services");
if (services.size() == 0) {
missingProperties.addAll(Arrays.asList(REQUIRED_KEYS));
return getConditionOutcome(missingProperties);
}
//gather indexes to check: [0], [1], [3], etc
Pattern p = Pattern.compile("\\[(\\d+)\\]");
Set<String> uniqueIndexes = new HashSet<String>();
for (String key : services.keySet()) {
Matcher m = p.matcher(key);
if (m.find()) {
uniqueIndexes.add(m.group(1));
}
}
//loop each index and check required props
uniqueIndexes.forEach(index -> {
for (String genericKey : REQUIRED_KEYS) {
String multiServiceKey = genericKey.replace("[i]", "[" + index + "]");
if (!resolver.containsProperty(multiServiceKey)) {
missingProperties.add(multiServiceKey);
}
}
});
return getConditionOutcome(missingProperties);
}
private ConditionOutcome getConditionOutcome(List<String> missingProperties) {
if (missingProperties.isEmpty()) {
return ConditionOutcome.match(ConditionMessage.forCondition(RequiredRepeatablePropertiesCondition.class.getCanonicalName())
.found("property", "properties")
.items(Arrays.asList(REQUIRED_KEYS)));
}
return ConditionOutcome.noMatch(
ConditionMessage.forCondition(RequiredRepeatablePropertiesCondition.class.getCanonicalName())
.didNotFind("property", "properties")
.items(missingProperties)
);
}
}

Old question, but I hope my answer will help for Spring2.x:
Thanks to #Brian, I checked migration guide, where I was inspired by example code. This code works for me:
final List<String> services = Binder.get(context.getEnvironment()).bind("my.services", List.class).orElse(null);
I did try to get List of POJO (as AutoConfigureService) but my class differs from AutoConfigureServices. For that purpose, I used:
final Services services = Binder.get(context.getEnvironment()).bind("my.services", Services.class).orElse(null);
Well, keep playing :-D

Here's my take on this issue with the use of custom conditions in Spring autoconfiguration. Somewhat similar to what #Strumbels proposed but more reusable.
#Conditional annotations are executed very early in during the application startup. Properties sources are already loaded but ConfgurationProperties beans are not yet created. However we can work around that issue by binding properties to Java POJO ourselves.
First I introduce a functional interface which will enable us to define any custom logic checking if properties are in fact present or not. In your case this method will take care of checking if the property List is empty/null and if all items within are valid.
public interface OptionalProperties {
boolean isPresent();
}
Now let's create an annotation which will be metannotated with Spring #Conditional and allow us to define custom parameters. prefix represents the property namespace and targetClass represents the configuration properties model class to which properties should be mapped.
#Target({ElementType.TYPE, ElementType.METHOD})
#Retention(RetentionPolicy.RUNTIME)
#Documented
#Conditional(OnConfigurationPropertiesCondition.class)
public #interface ConditionalOnConfigurationProperties {
String prefix();
Class<? extends OptionalProperties> targetClass();
}
And now the main part. The custom condition implementation.
public class OnConfigurationPropertiesCondition extends SpringBootCondition {
#Override
public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
MergedAnnotation<ConditionalOnConfigurationProperties> mergedAnnotation = metadata.getAnnotations().get(ConditionalOnConfigurationProperties.class);
String prefix = mergedAnnotation.getString("prefix");
Class<?> targetClass = mergedAnnotation.getClass("targetClass");
// type precondition
if (!OptionalProperties.class.isAssignableFrom(targetClass)) {
return ConditionOutcome.noMatch("Target type does not implement the OptionalProperties interface.");
}
// the crux of this solution, binding properties to Java POJO
Object bean = Binder.get(context.getEnvironment()).bind(prefix, targetClass).orElse(null);
// if properties are not present at all return no match
if (bean == null) {
return ConditionOutcome.noMatch("Binding properties to target type resulted in null value.");
}
OptionalProperties props = (OptionalProperties) bean;
// execute method from OptionalProperties interface
// to check if condition should be matched or not
// can include any custom logic using property values in a type safe manner
if (props.isPresent()) {
return ConditionOutcome.match();
} else {
return ConditionOutcome.noMatch("Properties are not present.");
}
}
}
Now you should create your own configuration properties class implementing OptionalProperties interface.
#ConfigurationProperties("your.property.prefix")
#ConstructorBinding
public class YourConfigurationProperties implements OptionalProperties {
// Service is your POJO representing the name and version subproperties
private final List<Service> services;
#Override
public boolean isPresent() {
return services != null && services.stream().all(Service::isValid);
}
}
And then in Spring #Configuration class.
#Configuration
#ConditionalOnConfigurationProperties(prefix = "", targetClass = YourConfigurationProperties.class)
class AutoConfigureServices {
....
}
There are two downsides to this solution:
Property prefix must be specified in two locations: on #ConfigurationProperties annotation and on #ConditionalOnConfigurationProperties annotation. This can partially be alleviated by defining a public static final String PREFIX = "namespace" in your configuration properties POJO.
Property binding process is executed separately for each use of our custom conditional annotation and then once again to create the configuration properties bean itself. It happens only during app startup so it shouldn't be an issue but it still is an inefficiency.

You can leverage the org.springframework.boot.autoconfigure.condition.OnPropertyListCondition class. For example, given you want to check for the service property having at least one value:
class MyListCondition extends OnPropertyListCondition {
MyListCondition() {
super("service", () -> ConditionMessage.forCondition("service"));
}
}
#Configuration
#Condition(MyListCondition.class)
class AutoConfigureServices {
}
See the org.springframework.boot.autoconfigure.webservices.OnWsdlLocationsCondition used on org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration#wsdlDefinitionBeanFactoryPostProcessor for an example within Spring itself.

DeltaSpike custom ConfigSource with CDI

I am trying to define a custom DeltaSpike ConfigSource. The custom config source will have the highest priority and check the database for the config parameter.
I have a ConfigParameter entity, that simply has a key and a value.
#Entity
#Cacheable
public class ConfigParameter ... {
private String key;
private String value;
}
I have a #Dependent DAO that finds all config parameters.
What I am trying to do now, is define a custom ConfigSource, that is able to get the config parameter from the database. Therefore, I want to inject my DAO in the ConfigSource. So basically something like
#ApplicationScoped
public class DatabaseConfigSource implements ConfigSource {
#Inject
private ConfigParameterDao configParameterDao;
....
}
However, when registering the ConfigSource via META-INF/services/org.apache.deltaspike.core.spi.config.ConfigSource, the class will be instantiated and CDI will not work.
Is there any way to get CDI working in this case?
Thanks in advance, if you need any further information, please let me know.

The main problem is, that the ConfigSource gets instantiated very early on when the BeanManager is not available yet. Even the JNDI lookup does not work at that point in time. Thus, I need to delay the injection/lookup.
What I did now, is add a static boolean to my config source, that I set manually. We have a InitializerService that makes sure that the system is setup properly. At the end of the initialization process, I call allowInitialization() in order to tell the config source, that the bean is injectable now. Next time the ConfigSource is asked, it will be able to inject the bean using BeanProvider.injectFields.
public class DatabaseConfigSource implements ConfigSource {
private static boolean allowInit;
#Inject
private ConfigParameterProvider configParameterProvider;
#Override
public int getOrdinal() {
return 500;
}
#Override
public String getPropertyValue(String key) {
initIfNecessary();
if (configParameterProvider == null) {
return null;
}
return configParameterProvider.getProperty(key);
}
public static void allowInitialization() {
allowInit = true;
}
private void initIfNecessary() {
if (allowInit) {
BeanProvider.injectFields(this);
}
}
}
I have a request-scoped bean that holds all my config variables for type-safe access.
#RequestScoped
public class Configuration {
#Inject
#ConfigProperty(name = "myProperty")
private String myProperty;
#Inject
#ConfigProperty(name = "myProperty2")
private String myProperty2;
....
}
When injecting the Configuration class in a different bean, each ConfigProperty will be resolved. Since my custom DatabaseConfigSource has the highest ordinal (500), it will be used for property resolution first. If the property is not found, it will delegate the resolution to the next ConfigSource.
For each ConfigProperty the getPropertyValue function from the DatabaseConfigSource is called. Since I do not want to retreive the parameters from the database for each config property, I moved the config property resolution to a request-scoped bean.
#RequestScoped
public class ConfigParameterProvider {
#Inject
private ConfigParameterDao configParameterDao;
private Map<String, String> configParameters = new HashMap<>();
#PostConstruct
public void init() {
List<ConfigParameter> configParams = configParameterDao.findAll();
configParameters = configParams.stream()
.collect(toMap(ConfigParameter::getId, ConfigParameter::getValue));
}
public String getProperty(String key) {
return configParameters.get(key);
}
}
I could sure change the request-scoped ConfigParameterProvider to ApplicationScoped. However, we have a multi-tenant setup and the parameters need to be resolved per request.
As you can see, this is a bit hacky, because we need to explicitly tell the ConfigSource, when it is allowed to be instantiated properly (inject the bean).
I would prefer a standarized solution from DeltaSpike for using CDI in a ConfigSource. If you have any idea on how to properly realise this, please let me know.

Even though this post has been answered already I'd like to suggest another possible solution for this problem.
I managed to load properties from my db service by creating an #Signleton #Startup EJB which extends the org.apache.deltaspike.core.impl.config.BaseConfigSource and injects my DAO as delegate which I then registered into the org.apache.deltaspike.core.api.config.ConfigResolver.
#Startup
#Singleton
public class DatabaseConfigSourceBean extends BaseConfigSource {
private static final Logger logger = LoggerFactory.getLogger(DatabaseConfigSourceBean.class);
private #Inject PropertyService delegateService;
#PostConstruct
public void onStartup() {
ConfigResolver.addConfigSources(Collections.singletonList(this));
logger.info("Registered the DatabaseConfigSourceBean in the ConfigSourceProvider ...");
}
#Override
public Map<String, String> getProperties() {
return delegateService.getProperties();
}
#Override
public String getPropertyValue(String key) {
return delegateService.getPropertyValue(key);
}
#Override
public String getConfigName() {
return DatabaseConfigSourceBean.class.getSimpleName();
}
#Override
public boolean isScannable() {
return true;
}
}
I know that creating an EJB for this purpose basically produces a way too big overhead, but I think it's a bit of a cleaner solution instead of handling this problem by some marker booleans with static accessors ...

DS is using the java se spi mechanism for this which is not CD'Injectable'. One solution would be to use the BeanProvider to get hold of your DatabaseConfigSource and delegate operations to it.

Spring switch implementations based on a runtime condition

This is a simplified version of what I am trying to achieve.
I have multiple implementations of the same interface. Based on the user input at runtime I want to pick the correct implementation.
For example suppose I an interface called Color. There are many classes that implement this interface, the Red class, the Blue class, the Green class and so on.
At run time I need to pick implementations based on the user input. One way to achieve this would be something like this
#Autowired
#Qualifier("Red")
private Color redColor;
#Autowired
#Qualifier("Green")
private Color greenColor;
private Color getColorImplementation()
{
if(userInput=="red")
{
return redColor;
}
else if(userInput=="green")
{
return greenColor;
}
else
{
return null;
}
}
But the problem with this is that everytime a new implementation is added, I would have to update the code that picks the implementation, which beats the whole purpose of inversion of control part of spring. What is the right way to do this using spring?

You could autowire all implementations of the interface in question and then decide based on properties provided by interface which to use.
#Autowired
private List<Color> colors;
public void doSomething(String input) {
colors.stream().filter(c -> c.getName().contains(input)).findFirst().ifPresent(c -> {
// something
}
}
This is also less magical and more in line with OO principles. Dependency injection is to wire up things initially, not for dynamic switching at runtime.

You want to Autowire the ApplicationContext, then you can get all the Color beans with Map<String, Color> colors = appContext.getBeansOfType(Color.class);. This presumes that the userInput and the bean name are identical.
If that isn't the case, a solution would be to add a getName() to the Color interface; then you can autowire a List<Color> and construct the Map yourself.
Can't you make the Color an Enum?

The Spring ServiceLocatorFactoryBean (scroll down to the middle) API was built just for this purpose:
Create a dummy interface (ColorFactory) that provides a single method such as Color getColor(String color)
Create the proxy bean instance for org.springframework.beans.factory.config.ServiceLocatorFactoryBean passing ColorFactory as the serviceLocatorInterface parameter
Define beans for all of your color implementations with names matching the parameter you'd like to pass to getColor
Inject the factory into the collaborators and invoke getColor as needed
You could contrive this with similar APIs on the ApplicationContext, but the advantage of this approach is that it abstracts Spring from your Java implementation (for XML configured projects).

Same issue happen in my implementation where in, the scenario was based on user input, where the respective interface implementation needs to be invoked.
This solve my problem:
**Base Interface**
#Service
public interface ParentInterface {
public String doThis(ClassA param);
}
**First Implementation**
#Component("FirstImp")
public class FirstServiceImp implements ParentInterface {
public String doThis(ClassA param){
}
**Second Implementation**
#Component("SecondImp")
public class SecondServiceImp implements ParentInterface {
public String doThis(ClassA param){
}
**Factory**
#Service
public class ServiceResolver {
#Autowired
#Qualifier("FirstImp")
private ParentInterface firstImpl;
#Autowired
#Qualifier("SecondImp")
private ParentInterface secondImpl;
public ParentInterface getInstance(String condition){
switch(condition) {
case "X": return firstImpl;
case "Y": return secondImpl;
default:
throw new IllegalArgumentException(condition);
}
}
}
**Controller**
#RestController
public class UserController {
#Resource
private ServiceResolver serviceresolver;
#PostMapping("/userbase/{inp1}/messages/{inptype}")
public ResponseEntity<String> sendData(#PathVariable String
inp1,#PathVariable String inptype, #RequestBody XYZBean msg)
{
for(ABC data : msg.getSubData())
serviceresolver.getInstance(data.getType()).doThis(msg);
return new ResponseEntity<String>("created",HttpStatus.OK);
}
}

Changing Guice bindings at runtime

I would like to be able to change the Guice injections at runtime to support multiple injections based on user input. This is what I would like to achieve:
public interface IDao {
public int someMethod();
}
public class DaoEarth implements IDao {
#Override
public int someMethod(){ ... }
}
public class DaoMars implements IDao {
#Override
public int someMethod(){ ... }
}
public class MyClass {
#Inject
private IDao myDao;
public int myMethod(String domain) {
//If Domain == Earth, myDao should be of the type DaoEarth
//If Domain == DaoMars, myDao should be of the type DaoMars
}
}
I was thinking of writing my own Provider, but I don't know how to use that provider to change my bindings at runtime. Any input is welcome and appreciated :)!
Update
Here's what I currently came up with, it's not as pretty as I'd like, so I'm still looking for feedback
public class DomainProvider {
#Inject #Earth
private IDaoProvider earthDaoProvider;
#Inject #Mars
private IDaoProvider marsDaoProvider;
public IDaoProvider get(Domain domain){
switch (domain){
case EARTH:
return earthDaoProvider;
case MARS:
return marsDaoProvider;
}
}
public IDaoProvider get(String domain){
Domain parsedDomain = Domain.valueOf(domain.toUpperCase());
return get(parsedDomain);
}
}
//MarsDaoProvider would be equivalent
public class EarthDaoProvider implements IDaoProvider {
#Inject #Earth
private IDao earthDao;
public IDao getDao() {
return earthDao;
}
}
// This means that in "MyClass", I can do:
public class MyClass {
#Inject
private DomainProvider domainProvider;
public int myMethod(String domain) {
IDaoProvider daoProvider = domainProvider.get(domain);
IDao dao = daoProvider.getDao();
//Now "dao" will be of the correct type based on the domain
}
}
//Of course elsewhere I have the bindings set like
bind(IDao.class).annotatedWith(Earth.class).to(EarthDao.class);

Your version is almost perfect as it is: You're going to need to inject some kind of object that returns one or the other based on code you write, and don't need assisted injection or anything like that. That said, you can skip some of the boilerplate:
public class DomainProvider {
// Just inject Providers directly without binding them explicitly.
#Inject #Earth Provider<IDao> earthDaoProvider;
#Inject #Mars Provider<IDao> marsDaoProvider;
public Provider<IDao> get(Domain domain){
switch (domain){
case EARTH:
return earthDaoProvider;
case MARS:
return marsDaoProvider;
}
}
public Provider<IDao> get(String domain){
Domain parsedDomain = Domain.valueOf(domain.toUpperCase());
return get(parsedDomain);
}
}
Your MyClass in that case would be exactly identical. Here, Provider is either the one-method generic interface com.google.inject.Provider, or the equivalent builtin javax.inject.Provider that it extends. Read more about Guice Providers on the relevant Guice wiki topic.
bind(IDao.class).annotatedWith(Earth.class).to(EarthDao.class);
// You can now inject "#Earth IDao" and also "#Earth Provider<IDao>".
Basically, if you bind a key Foo (to a class, provider, #Provides method, or instance), you automatically get to inject either a Foo or Provider<Foo> with no additional work. Providers are also a great way to ensure that you get a new instance with every call to get, if that's what you want; with your original, you'll always get the same instance of EarthDao or MarsDao for any given DomainProvider you inject. (If you have a scoped binding like #Singleton, Guice will respect that too; Provider just lets Guice get involved, rather than reusing a plain old Java reference.)
This means you can skip your custom EarthDaoProvider and MarsDaoProvider, unless you really need to perform any external initialization on them—at which point you'd probably be better off calling bind(EarthDao.class).toProvider(EarthDaoProvider.class) so the preparation also happens when injecting EarthDao directly. You could also just have DomainProvider return an IDao instance directly by calling get on the appropriate Provider, and be assured that it'll be a new instance every time.

How can I validate a field as required depending on another field's value in SEAM?

I'm trying to create a simple custom validator for my project, and I can't seem to find a way of getting seam to validate things conditionally.
Here's what I've got:
A helper/backing bean (that is NOT an entity)
#RequiredIfSelected
public class AdSiteHelper {
private Date start;
private Date end;
private boolean selected;
/* getters and setters implied */
}
What I need is for "start" and "end" to be required if and only if selected is true.
I tried creating a custom validator at the TYPE target, but seam doesn't seem to want to pick it up and validate it. (Maybe because it's not an entity?)
here's the general idea of my custom annotation for starters:
#ValidatorClass(RequiredIfSelectedValidator.class)
#Target(ElementType.TYPE)
#Retention(RetentionPolicy.RUNTIME)
public #interface RequiredIfSelected {
String message();
}
public class RequiredIfSelectedValidator implements Validator<RequiredIfSelected>, Serializable {
public boolean isValid(Object value) {
AdSiteHelper ash = (AdSiteHelper) value;
return !ash.isSelected() || (ash.getStart() && ash.getEnd());
}
public void initialize(RequiredIfSelected parameters) { }
}

I had a similar problem covered by this post. If your Bean holding these values is always the same then you could just load the current instance of it into your Validator with
//Assuming you have the #Name annotation populated on your Bean and a Scope of CONVERSATION or higher
AdSiteHelper helper = (AdSiteHelper)Component.getInstance("adSiteHelper");
Also as you're using Seam your validators don't need to be so complex. You don't need an interface and it can be as simple as
#Name("requiredIfSelectedValidator")
#Validator
public class RequiredIfSelectedValidator implements javax.faces.validator.Validator {
public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
//do stuff
}
}