I have method with one input which I use for logging purposes only.
How can I use #Cacheable on this method while ignoring the input?
(using Ehcache and spring #Cacheable annotation)
Thanks
You can configure the #Cacheable annotation with the key attribute and give it a constant value, thus ignoring your input parameter.
See the documentation for details.
Related
How to read a value from application.yml in my Micronaut project? I can clearly see annotation is resolved to proper value (true in this case), but it is not applied to the variable (stays as default false). I've tried using #Value and #ConfigurationProperties
In a comment the OP has indicated that they are doing new FeatureToggleService(). Creating your own instance of the object is the problem. Instead of using new, let the DI container create and manage the instance. If you do, then #Value will be relevant.
See https://github.com/jeffbrown/filiard/blob/f6f704fb95d7821919748bb41968f87d11cee07b/src/main/java/filiard/DemoController.java and https://github.com/jeffbrown/filiard/blob/f6f704fb95d7821919748bb41968f87d11cee07b/src/main/java/filiard/FlagHelper.java for a working example.
UPDATE:
Based on additional information this is not the correct answer!!!
As pointed out, #Value can be private, but Micronaut advices against it.
Short answer, it is because it is private. Wrong
From the documentation:
The #Value annotation accepts a string that can have embedded placeholder values (the default value can be provided by specifying a
value after the colon : character). Also try to avoid setting the
member visibility to private, since this requires Micronaut Framework
to use reflection. Prefer to use protected.
Also, consider using #Property instead of #Value. Still valid
https://docs.micronaut.io/latest/guide/#valueAnnotation
NOTE:
The Micronaut framework does not inspect a manually created instance, even if it is instantiated in a #Factory, unlike other frameworks.
You are using the Pageable object provided by Spring, and you need to display this object through swagger. I am using Custom Annotation.
I want to change the size value of #ApiImplicitParam according to the ApiPageable Annotation variable.
Please refer to the picture below.
Difference between #Value and #ConfigurationProperties?
In which scenario should I use #Value or #ConfigurationProperties?
#RefreshScope will refresh properties value for both?
I was questioning the same, to myself, and I found a concrete reason and why is better to use ConfigurationProperties over Value.
The main reason is that you could end with some text in the code forcing you to do full-text search to understand where a Value property is used.
You can find the whole explanation in in this lightweith reading: https://tuhrig.de/why-using-springs-value-annotation-is-bad/
Insteead of using #Value annotation multiple time to read value from properties file .we can use #configurationProperties one time
I need to create a means to add a custom annotation like
#Value("${my.property}")
However, in my case I need to get the value from a database rather then a properties file.
Basically I would like to create a bean on container startup that reads in property name value pairs from a database and can then inject these into fields belonging to other beans.
Approach #1:
One way is to create an Aspect, with a point-cut expression that matches any method having this annotation.
Your aspect will then:
Read the property value in the annotation
Look up the required value an inject it into the class.
AOP Kickstart
Here's a guide to getting started with AOP in Spring
http://www.tutorialspoint.com/spring/aop_with_spring.htm
Joinpoint matching
Here's a reference that describes how to create a join-point that matches on annotations: http://eclipse.org/aspectj/doc/next/adk15notebook/annotations-pointcuts-and-advice.html
Approach #2:
Another way is to use a BeanFactoryPostProcessor - this is essentially how a PropertyPlaceholderConfigurer works.
It will look at your bean definitions, and fetch the underlying class.
It will then check for the annotation in the class, using reflection.
It will update the bean definition to include injecting the property as per the value in the annotation.
. . actually I think approach #2 sounds more like what you want - all of the processing happens on "start-up". . . (In actual fact your modifying the bean recipes even before startup). . whereas if you used AOP, you'd be intercepting method invocations, which might be too late for you?
Namespace Handler
If you wanted you could even create your own Spring namespace handler to turn on your post processor in a terse way. Eg:
<myApp:injectFromDb />
as an alternative to:
<bean class="MyDatabaseLookupProcessorImpl etc, etc. />
Update: Approach #3
As of Spring 3.1 there's also the PropertySourcesPlaceholderConfigurer, that will provide most of the plumbing for you, so you can achieve this with less code.
Alternatively you should be able to configure kind of properties repository bean and then use it in SpEL directly in #Value annotation.
Let's say you'd have bean called propertiesRepository in your context that implements following interface:
interface PropertiesRepository {
String getProperty(String propertyName);
}
then on bean where you want to inject values you can use following expression
#Value("#{propertiesRepository.getProperty('my.property')}")
String myProperty;
You can use #Value annotation by injecting database configuration in application environment itself.
I know this is an old question but I didn't find an exact solution. So documenting it here.
I have already answered the same on different forum.
Please refer to this answer for exact solution to your problem.
I want to use the #Cachable annotation on one of my methods, but I have the problem, that the result depends on an attribute of a spring bean that is not part of the method signature.
So I want something like this:
#Cachable(value="mycache", key="#id, #myspringbean.referenceId")
MyResult myMethod(int id);
I guess these are actually two problems: How to get use a composite key and how to use another spring bean in the expression.
The problem of how to use a composite key can probably be solved like in this SO question: #Cacheable key on multiple method arguments
However, I could not find anythig about how to reference to another spring bean in this expression. Is it possible and if yes, how?
You can have a lot a details on SpEL in the Spring documentation (http://static.springsource.org/spring/docs/3.2.x/spring-framework-reference/html/expressions.html). As you can see, you can use bean references using the #myBean syntax. You have to include a bean resolver in your context to do that.
It's not possible to use the current Spring bean name.
I think I would use the following pattern so that each bean object will have it's own "key-space" see also What can be the default key generator.
As for the problem above one can use:
#Cachable(value="mycache", key = "{#id, #root.targetClass.getDeclaredField('attribute').get(#root.target)}")
MyResult myMethod(int id);
just make sure your attribute is public