Can't I use @Value annotation with @Transient annotation?

Question

I have a class to map a table for using hibernate. There are some variable I want to ignore for mapping to use as constant. And I want to load constant value from properties so I code it like this:

@Transient
@Value("${something.value}")
private int MY_VALUE;

But, the value of MY_VALUE is always set to 0. Can't I use @Transient annotation with @Value annotation? Or I missed something else?

if you remove the `@Transient` annotation, it continues to be set to `0`? — bluefoot, Jul 26 '11 at 01:32
@bluefoot If I remove that the project throws error, because of this issue http://stackoverflow.com/questions/4662582/how-to-make-hibernate-ignore-class-variables-that-are-not-mapped — Sanghyun Lee, Jul 26 '11 at 01:39

score 6 · Answer 1 · answered Jul 26 '11 at 01:37

Those two annotations belong in different domains.

@Transient belongs to an entity, while @Value belongs to Spring Beans. Entities are managed by JPA / Hibernate, Spring Beans are managed by Spring. It is not a good idea to mix the two.

You could achieve this by using the @Configurable annotation and AspectJ compilation or Load Time Weaving, but I would strongly advise against such a hack. Use a Spring Bean to hold a @Value, not an entity!

score 4 · Accepted Answer · answered Jul 26 '11 at 01:39

4

You use @Value to specify a property value to load when Spring creates the bean.

However, if you are using Hibernate to load data from a database, Spring is not instantiating these classes for you. So your @Value annotation has no effect.

I would suggest injecting the @Value into the DAO that loads these entities from Hibernate, something like

public class FooDao {
    @Value("...")
    private int yourConfiguredValue;

    public getFoo() {
        Foo foo = sessionFactory.getCurrentSession().get(...);
        foo.setYourValue(yourConfiguredValue);
        return foo;
    }
}

answered Jul 26 '11 at 01:39

matt b

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I get `foo` as a list like `List foos = ...`. Is it good idea to inject the `@Value` into every objects with loop? – Sanghyun Lee Jul 26 '11 at 01:52
2

Well if you need to add the value to each object, what other way is there? However I would consider not having this value attached to the entity object at all if it's constant and/or from a properties file - doesn't sound like it's related to *each* instance of Foo, especially if they all have the same value. I'd attach that @Value to some other class. – matt b Jul 26 '11 at 02:00

score 1 · Answer 3 · answered Jun 06 '20 at 10:49

In my scenario I have a class Employee which has relation with class Organization.

I don't want to serialize a whole dependent object(Organization), rather serialize a single parameter of organization(e.g. orgID).

I tried following:

@Transient
@value("#{target.orgId.id}")
private UUID org_Id;

but it didnt work. So i used a simple getter mehtod instead of a field variable as follows:

@JsonIgnore
@ManyToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "orgID")
private Organization orgId;

@JsonProperty("orgId")
public UUID getOrg_ID() {
    return orgId.getId();
}

it worked and i got simple orgId field in response serialized by Jackson. It seems Jackson work with getters without considering a field variable is declared or not corresponding to that getter method.

Can't I use @Value annotation with @Transient annotation?

3 Answers3