kotlinlang #spring

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
abstract class Credential(
        @ManyToOne
        @JoinColumn
        val account: Account
) {

    @Id
    val id = UUID.randomUUID()

    @Enumerated(EnumType.STRING)
    @Column(name = "DTYPE", insertable = false, updatable = false)
    var type: CredentialType = CredentialType.UNKNOWN
        private set

pixelbumper

08/06/2017, 2:31 PM

I am starting to wonder if val is to be avoided on jpa entities and instead have private setters where immutability is desired

pixelbumper

08/06/2017, 2:36 PM

the funny thing is that i can even make it a val and it will still work ^^

pixelbumper

08/06/2017, 2:49 PM

reading the manual clarified the val issue

pixelbumper

08/06/2017, 2:49 PM

@User uploaded a file:

image.png▾

pixelbumper

08/06/2017, 2:50 PM

in turn that means i shall not be using val in entity classes.

pixelbumper

08/06/2017, 2:59 PM

Copy code

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
abstract class Credential(
        account: Account
) {

    @ManyToOne
    @JoinColumn
    var account: Account = account

    @Id
    var id = UUID.randomUUID()
        private set

    @Enumerated(EnumType.STRING)
    @Column(name = "DTYPE", insertable = false, updatable = false)
    var type: CredentialType = CredentialType.UNKNOWN
        private set

guess this is the propper way to do it. Objections?

cleiter

08/07/2017, 7:18 AM

@pixelbumper i'm using the kotlin noargs compiler plugin for my entities and most of them are defined as `data class`es with `val`s. so pass everything that's needed in the constructor

pixelbumper

08/07/2017, 7:39 AM

@cleiter Hi 🙂 I am using the kotlin-jpa compiler plugin already, which ensures that Entity classes are opened and have a noarg constructor (as far as I have understood). Using data classes was my original approach, but the fact that data classes use all fields in their hashcode and equals method make them unusable for me as I need to have equals and hashcode use only the fields that define their business identity. The only thing that I am not sure about, is if the usage of val is fine. This is mainly because of the section of the hibernate documentation that I have sent before, as it states that it is not recommended to have final fields.

cleiter

08/07/2017, 7:40 AM

okay, don't need to be data classes (or overwrite `equals`/`hashCode`)

pixelbumper

08/07/2017, 7:40 AM

It works either way with val or var. The only thing that left me puzzeled if it is a recommended practice

cleiter

08/07/2017, 7:41 AM

i use this approach with hibernate and eclipselink and it works fine

cleiter

08/07/2017, 7:42 AM

your jpa provider can still inject final fields on construction

pixelbumper

08/07/2017, 7:46 AM

So it is ok? Because the hibernate docs seem to state otherwise 🤔

cleiter

08/07/2017, 7:50 AM

it may not be according to spec but it works in all jpa providers. i use it since it's less hassle and if it would actually break in the future i'd have to live with the consequences

cleiter

08/07/2017, 7:50 AM

but i think that's really unlikely since most likely many projects depend on that behaviour

pixelbumper

08/07/2017, 7:51 AM

I see. Thank you for your comments 😄

tjb

08/07/2017, 9:34 PM

hello everyone how would i go about having a shared global variable (its a session) on application bootup that i could access in multiple services?

timp

08/07/2017, 9:46 PM

Create a class, and stick a @component annotation on it. Then add your class to the constructor of any services where you need it. spring will create one instance of your class(singleton) and then inject it into all your services via constructor injection for you

dharrigan

08/08/2017, 2:06 PM

Soooo....

dharrigan

08/08/2017, 2:07 PM

using Kotlin 1.2-M1, have an annotation,

@SpringBootTest(classes = arrayOf(Application::class))

dharrigan

08/08/2017, 2:07 PM

I take the recommendation, and replace it with an array literal

dharrigan

08/08/2017, 2:07 PM

@SpringBootTest(classes = [(Application::class)])

dharrigan

08/08/2017, 2:08 PM

get this:

dharrigan

08/08/2017, 2:08 PM

Caused by: java.lang.IllegalArgumentException: Collection has more than one element.

dharrigan

08/08/2017, 2:08 PM

known issue?

enleur

08/08/2017, 3:03 PM

@SpringBootTest(classes = [Application::class])

should it be like this?

dharrigan

08/08/2017, 3:36 PM

that too fails

dharrigan

08/08/2017, 3:37 PM

(with same error message)

dharrigan

08/08/2017, 4:12 PM

I've raised a bug