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
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.
I'm trying to register an autoconfiguration with #ConditionalOnProperty. This configuration should be created when there is any property with a predefined prefix.
For example, this configuration should be created when there is one of the properties listed below
test.property.any-text-goes-here.some-nested-property=test
test.property.nested.nested-two=another
I've tried to use #ConditionalOnProperty with name=test.property, but it doesn't seem to be working. Maybe this can be sorted out using #ConditionalOnExpression, but I have no idea how SpEL expression should look like.
I'm wondering if there a way to achieve this without the need of implementing custom Condition.
Thanks for your help!
Unfortunately, it is not possible. #ConditionalOnProperty evaluates and compares only final property values in flat structure. It does not work on objects :(
I am facing a situation in which a bean should be created by the application context only if the property contains any other value than a specific value.
i.e... one property file.path= /specific/path, If the value is other than this then bean should be loaded.
I can see that there is #ConditionalOnProperty (name="file.path", havingValue="....") out of the box but in my case, I am looking a property like havingValueOtherThan="..." or similar kind of property or annotation if it is there out of the box in the spring.
There are many possible options, besides profiles that were stated in comments, here are 2 options:
Option 1
Use #ConditionalOnExpression with any SPeL expression you wish
Option 2
You can always create your own conditional annotation with any logic:
Create an annotation that will depict your own business case with a #Conditional on it.
Then Implement the conditional logic of your choice. Here is an example of achieving this.
BTW, the profiles that mentioned in comments are using Conditionals engine under the hood (The #Profile annotation has a #Conditional({ProfileCondition.class}) in its definition since Spring 4.x)
I have some code to load a value as such in my Spring application:
#Component
public class MyElasticRestService {
#Value("${elasticApi.baseURL}")
private String elasticApiBaseUrl;
According to the Spring docs, I should be able to use a relaxed binding that comes from an uppercase environment variable such as ELASTIC_API_BASE_URL or ELASTICAPI_BASEURL. But I'm confused which is correct. Both don't seem to work so I am wondering how to debug what is actually picked up.
I've loaded Spring Boot Actuator to view the configprops endpoint. But it doesn't have anything on the elasticApi prefix.
What should the correct environment variable be and how can I see how it gets translated and picked up by the application?
The #Value annotation doesn't support relaxed bindings. Therefore you could use a class annotated with #ConfigurationProperties or you use a RelaxedPropertyResolver to get the value from the environment.
According to https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-external-config-vs-value, it is now very possible simply with #Value as long as you use kebab-case (all lower case with dash) for the name e.g. #Value("config.refresh-rate")
Instead of trying to make it an UPPER_SNAKE_CASE, you can put it in your application.yaml file, this way:
elasticApi.baseURL: ${ELASTIC_API_BASE_URL:defaultvalue}
or this way doesn't really matter:
elasticApi:
baseURL: ${ELASTIC_API_BASE_URL:defaultvalue}
I need to create a means to add a custom annotation like
#Value("${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.