I have a property that holds Redis port in my Redis config class.
#Value("\${redis.port:63799}")
lateinit var port: Integer
init {
this.redisServer = RedisServer(port.toInt())
}
When I run my code I get this error:
kotlin.UninitializedPropertyAccessException: lateinit property port has not been initialized
#Value annotation is processed after the object is constructed.
The init block is part of object construction (it's common for all your constructors).
In other words, you're trying to reference the #Value injected property too early.
One way to work around it is to delay RedisServer construction in some way, i.e.:
Use lazyinit for the RedisServer.
Use #PostConstruct on a method to initialise the RedisServer.
Related
I am trying to inject a map property inside my spring-component class using #Value annotation.
My class is something like this
#Service
class SomeService {
#Value("#{\${some.map.property}}")
lateinit var map: Map<String, Boolean>
}
If my application.properties is as -
some.map.property={a:true}
The injection works fine. But if the value is empty i.e. something like this
some.map.property={}
The application throws an error lateinit property map has not been initialised. Is there a way in spring to initialise the map to an empty map if the value of the property is {}.I have a condition that this property will always be there and only the value of the property can change. I am using spring boot version -> 2.7.1 and the app is built using Kotlin.
If the property is set to {}, then I am getting property uninitialised error. If the value is present it works fine.
Given I always have to keep the property and can only change the value. Is there a way to initialise the property with an empty map if the value is {}.
I can always read the property as string and do a conversion to Map. But I want to avoid that.
Thanks!
So the problem with your code is that whenever you pass:
some.map.property={}
You will receive:
kotlin.UninitializedPropertyAccessException: lateinit property map has not been initialized
Because {} is mapped to null, but you are expecting to have Map<String, Boolean> that's why you have a problem.
The solution is simple, you can use the default value if null occurs:
#Value("#{\${some.map.property}}")
val map: Map<String, Boolean> = emptyMap()
In that case for {} value in your property it will be mapped to empty map.
I want to initialise a member variable from a value I pick from ENV but it is not available in init block as it gets picked up after object initialisation
private lateinit var needValueHere: String
#Value("\${CLIENT_ID:NA}")
private val CLIENT_ID: String = ""
init {
this.needValueHere = this.CLIENT_ID
}
This is a simplified version of the actual problem.
I have verified the value is available in the member functions.
Your object is constructing by the following way:
Create object (e.g. call constructor)
Via reflection: put dependencies (e.g. fill values under #Autowired, #Value and other annotations).
Your init block is part of constructor, e.g. all Spring-related items aren't initialized here.
How you can fix this:
Extract properties to the type-safe configuration (please see official docs here)
Use notation of class like below.
Create private lateinit var field and don't call it until Spring initialization finishing (this is useful for integration tests, e.g. test methods start only after full warmup). Another option - use kotlin lazy notation. However whole this item couldn't be named as "good code".
class MyService(#Value("\${CLIENT_ID:NA}") private val needValueHere: String) {
/* */
}
I am using spring framework.
I am using objectMapper to desiriale store.json file:
service:
objectMapper.readValue(new File(jsonFilePath), Store.class)
store.json:
{
"type": "Store",
"name": "myStore",
}
Store.class:
#Value("${store.size:1000}")
private Integer sroreSize;
#autowire
private storePersistency storePersistency;
public Store(#JsonProperty("name") String name) {
super(name);
}
I am trying find out how to #autowire beans and #value properties in store.class, beans and properties that exist in applicationContext.
In current example sroreSize and storePersistency still null.
I know that I can inject fields to object mapper and then use #JacksonInject annotation but I have a lot of field to inject - not a good option for me.
Custom desirializer also not a good option for me.
Is there any way not to use custom desirializer or not to inject every bean/property that I need in store.class?
Something that injects all the beans and properties and I simply can use it in Store.class.
So you want some Store fields like storePersistency and sroreSize to be initialized once at application startup (which is when Spring will setup the application context) and then at runtime create multiple different Store objects differing in some fields as name that are initialized by Jackson.
I suggest annotating Store with #Component to get Spring to initialize #Value and #Autowired fields. The #Scope annotation will cause a new independent Store instance to be created each time. Simplified example:
#Component
#Scope(SCOPE_PROTOTYPE)
class Store {
private String name;
#Value("${store.size:1000}")
private Integer sroreSize;
}
Then the key is method readerForUpdating where you can pass an existing instance of Store and Jackson will update that instead of creating a new one as usually:
Store store = context.getBean(Store.class);
objectMapper.readerForUpdating(store).readValue("{\"name\":\"myStore\"}");
Where context is a Spring ApplicationContext reference that I autowired in a test class. You don't need to use the return value of readValue in this case, just inspect the existing store variable and name will be updated.
Java Spring question:
I have a interface MyInterface with one method
void exec (String str);
I have many implementation of MyInterface, say Oneimpl, anotherimpl yetanotherimpl...and so on and can keep adding new implementations.
how do I obtain an instance of a specific implementation using just the name of the implementing class passed as a STRING value , say "someRandomImpl"
The code should be dynamic and can provide a instance of new implementations without code change.
implements ApplicationContextAware
it will autowired ApplicationContext object
use the object like
context.getBean(beanName)
then you get the bean
If I have:
#Autowired private ApplicationContext ctx;
I can get beans and resources by using one of the the getBean methods. However, I can't figure out how to get property values.
Obviously, I can create a new bean which has an #Value property like:
private #Value("${someProp}") String somePropValue;
What method do I call on the ApplicationContext object to get that value without autowiring a bean?
I usually use the #Value, but there is a situation where the SPeL expression needs to be dynamic, so I can't just use an annotation.
In the case where SPeL expression needs to be dynamic, get the property value manually:
somePropValue = ctx.getEnvironment().getProperty("someProp");
If you are stuck on Spring pre 3.1, you can use
somePropValue = ctx.getBeanFactory().resolveEmbeddedValue("${someProp}");
Assuming that the ${someProp} property comes from a PropertyPlaceHolderConfigurer, that makes things difficult. The PropertyPlaceholderConfigurer is a BeanFactoryPostProcessor and as such only available at container startup time. So the properties are not available to a bean at runtime.
A solution would be to create some sort of a value holder bean that you initialize with the property / properties you need.
#Component
public class PropertyHolder{
#Value("${props.foo}") private String foo;
#Value("${props.bar}") private String bar;
// + getter methods
}
Now inject this PropertyHolder wherever you need the properties and access the properties through the getter methods