Koin: [2.0.0-GA] Just before the release!

[arnaudgiuliani]

Hi Koin users,

the Koin 2.0.0-GA has been published with the last changes for the final release. I need now to polish/update/write documentation to help you use all of that.

You can check the last changes in the changelog: https://github.com/InsertKoinIO/koin/blob/master/CHANGELOG.md

Some latest updates:

• injectOrNull & getOrNull to retrieve a potential instance
• bind/binds operator has been simplified to tag secondary types for definition. This secondary type can be reached with getAll & bind functions
• getAll to request all definitions regarding primary & secondary types
• bind to request an entity thanks to its primary and secondary type single { MyComponent() } bind Component::class can be found via bind<MyComponent,Component>()
• internals has been reworked to use scope mechanism as primary primitive work level: Koin works now with its root scope by default. If you want to request a dependency from a scope, just create/retrieve it and use it directly.
• Scope DSL has been limited. Now you can't try to declare single/factory in scope section.
• now possible to declare a type in different scopes

val koin = koinApplication {
            modules(
                    module {
                        scope(named("B")) {
                            scoped { Simple.ComponentA() }
                        }
                        scope(named("A")) {
                            scoped { Simple.ComponentA() }
                        }
                    }
            )
        }.koin

        val scopeA = koin.createScope("A", named("A")).get<Simple.ComponentA>()
        val scopeB = koin.createScope("B", named("B")).get<Simple.ComponentA>()
        scopeA & scopeB => are different!

If you find a problem, help us & give your feedback!

Final release 2.0.0 is on the road 👍

Cheers.

[darkrossi]

Good morning Arnaud,

_I can't use the scope feature with my MVVM architecture_.

It has been said that the instance of my view model can't be created.

Could not create instance for [type:Factory,class:'MyActivityViewModel']

More precisely, the first error in the stacktrace concerns the definition of the view model constructor's parameter which is not found :

No definition found for 'EventCollectorInterface' has been found. Check your module definitions.

My injections file

    scope(named<MyActivity>()) {
        scoped { EventCollectorService() as EventCollectorInterface }
        viewModel { MyActivityViewModel(get()) }
    }

My activity

class MyActivity : AppCompatActivity() {
    private val viewModel by viewModel<MyActivityViewModel>()
    ...
}

My view model definition

class MyActivityViewModel(
    private val eventCollectorInterface: EventCollectorInterface
) : ViewModel()

[arnaudgiuliani]

A ViewModel is not tied to a scope. You can't declare a viewModel in a scope. To use a scoped definition instance from a ViewModel, pass it the scopeId that you need:

// Your ViewModel that use a defintion from a scope
viewModel { (scopeId : ScopeID) -> MyActivityViewModel(getScope(scopedId).get()) }

// Your scope
scope(named<MyActivity>()) {
    scoped { EventCollectorService() as EventCollectorInterface }
}

// retrieve your ViewModel by passing the scopeId
val viewModel by viewModel<MyActivityViewModel> { parametersOf(currentScope.id) }

[knordbo]

It looks like qualifiers are not cached in combination with the type, making this code fail:

module {
    single<String>(named("foo")) { "hello world" }
    single<Long>(named("foo")) { 1L }
}

org.koin.core.error.DefinitionOverrideException: Already existing definition or try to override an existing one with qualifier 'foo' with [type:Single,name:'foo', class:'java.lang.Long'] but has already registered [type:Single,name:'foo', class:'java.lang.String']
at org.koin.core.registry.BeanRegistry.saveDefinitionForName(BeanRegistry.kt:110)

This worked before, and I would expect it to still work since the same qualifiers are typically used across domains.

Edit:
Works fine if I change koin-core to use qualifier.toString() + "@" + kClass.getFullName() instead of qualifier.toString(), is this change desired? Happy to put up the actual change.

[darkrossi]

A ViewModel is not tied to a scope. You can't declare a viewModel in a scope. To use a scoped definition instance from a ViewModel, pass it the scopeId that you need:

// Your ViewModel that use a defintion from a scope
viewModel { (scopeId : ScopeID) -> MyActivityViewModel(getScope(scopedId).get()) }

// Your scope
scope(named<MyActivity>()) {
    scoped { EventCollectorService() as EventCollectorInterface }
}

// retrieve your ViewModel by passing the scopeId
val viewModel by viewModel<MyActivityViewModel> { parametersOf(currentScope.id) }

It works perfectly 👍

Thank you for all your work!

[dkrivoruchko]

module { single { SettingsImpl(get()) as Settings } bind SettingsReadOnly::class }
in Android Fragment
private val settingsReadOnly: SettingsReadOnly by inject()
got

NoBeanDefFoundException: No definition found for 'info.dvkr.screenstream.data.settings.SettingsReadOnly' has been found. Check your module definitions.

[arnaudgiuliani]

yes, secondary types are now found by bind & getAll. You will find your component by: getKoin().bind<Settings,SettingsReadOnly>()

This way you can have several components bound your secondary type, here SettingsReadOnly

[arnaudgiuliani]

but let me check to get it back in get()... to allow you to retrieve it naturally if you only have one component for a secondary type.

[arnaudgiuliani]

publishing 2.0.0-GA2 with several fixes for additional types:

To sum up:

module {
    single { Simple.Component1() } bind Simple.ComponentInterface1::class
    single { Simple.Component2() } bind Simple.ComponentInterface1::class
    single { Simple.UserComponent(bind<Simple.Component1, Simple.ComponentInterface1>()) }
}

• you can get directly the instances with get<Simple.Component1>(), get<Simple.Component2>()
• get<Simple.ComponentInterface1>() will throw an error and tell you to use bind because can’t choose between the 2 definitions
• you can use bind<>() to resolve a component in the DSL
• getAll<Simple.ComponentInterface1>() give us the 2 instances

In a situation with only one definition for a secondary type, get would return the right instance directly:

module {
    single { Simple.Component1() } bind Simple.ComponentInterface1::class
}

// returns the right instance
get<Simple.ComponentInterface1>() 

[REPLicated]

@arnaudgiuliani : Regarding your last point above, the following does not work for me (self-contained example):

interface TransactionManager
interface ConnectionProvider
class TransactionManagerImpl: TransactionManager, ConnectionProvider

val koinDbModule = module {
    single<TransactionManager> { TransactionManagerImpl() } bind ConnectionProvider::class
}

class AppTest: KoinComponent {
    @Test
    fun run() {
        startKoin {
            modules(koinDbModule)
        }

        val connectionProvider: ConnectionProvider = get()

    }
}

Results in:

No definition found for 'koinplayground.ConnectionProvider' has been found. Check your module definitions.
org.koin.core.error.NoBeanDefFoundException: No definition found for 'koinplayground.ConnectionProvider' has been found. Check your module definitions.
    at org.koin.core.scope.Scope.findDefinition(Scope.kt:146)
    at org.koin.core.scope.Scope.resolveInstance(Scope.kt:140)
    at org.koin.core.scope.Scope.get(Scope.kt:131)
    at koinplayground.AppTest.run(AppTest.kt:39)

Why is that? I only have one definition for the secondary type.

[arnaudgiuliani]

check with 2.0.0-GA2

[REPLicated]

@arnaudgiuliani : Ok, I will try to upgrade as soon as you publish those artifacts.

[arnaudgiuliani]

already online: https://bintray.com/ekito/koin

[REPLicated]

Sorry, I missed that. It would be nice if you could always publish to JCenter and create a release on Github (like you did for 2.0.0-GA).

[alexbchr]

@arnaudgiuliani In RC2, we had possibility to pass a scope reference to KoinJavaComponent get and inject methods. As of GA2, it is no longer possible? How can I reference a scoped instance from Java code from now on?

[arnaudgiuliani]

@alexbchr you have to create a scope, but API is less Java friendly. Can you open a ticket?

[erickok]

Yeah we have the same issue, extremely tricky to get a scope from Java and to get a dependency with it.

[alexbchr]

For future reference, here is the related issue #451

[arnaudgiuliani]

@alexbchr thanks 👍

[arnaudgiuliani]

KoinJavaComponent fixed back with scope property in 2.0.0-GA3

[renaudcerrato]

Removing the scope parameter from get() / inject() is definitely a nice step forward. It was confusing at best and, worst, could introduce some nasty side effects since the scope was lazily evaluated using inject().

[lucaspommateau]

Any ideas on when the final 2.0.0 will be published?

[arnaudgiuliani]

normally, before the end of the month 👍

[nksaroj]

Below is the code I am using for using Koin components in some legacy Java classes with Koin 2.0.

import org.koin.core.Koin
import org.koin.core.context.GlobalContext
import org.koin.core.parameter.ParametersDefinition
import org.koin.core.scope.ScopeInstance

object KoinJavaUtils {


    /**
     * Retrieve given dependency lazily
     * @param clazz - dependency class
     * @param name - bean canonicalName / optional
     * @param scope
     * @param parameters - dependency parameters / optional
     */
    @JvmOverloads
    @JvmStatic
    fun <T : Any> inject(
            clazz: Class<T>,
            name: String? = null,
            scope: ScopeInstance? = null,
            parameters: ParametersDefinition? = null
    ): Lazy<T> {
        return lazy { get(clazz, name, scope, parameters) }
    }

    /**
     * Retrieve given dependency
     * @param clazz - dependency class
     * @param name - bean canonicalName / optional
     * @param scope - scope
     * @param parameters - dependency parameters / optional
     */
    @JvmOverloads
    @JvmStatic
    fun <T : Any> get(
            clazz: Class<T>,
            name: String? = null,
            scope: ScopeInstance? = null,
            parameters: ParametersDefinition? = null
    ): T {
        return getKoin().get(
                clazz.kotlin,
                name,
                scope,
                parameters
        )
    }

    /**
     * inject lazily given property
     * @param key - key property
     */
    @JvmStatic
    fun getKoin(): Koin = GlobalContext.get().koin
}

During the process of migration to 2, I've get to see org.koin.core.scope.ScopeInstance package unresolved reference.
.
It would be great if anyone can give me a hand for this class migration. I ran out of options due to not much doco. Appreciated your help!