metadata-ktx

MetaObjects :: Metadata Kotlin Facade (metadata-ktx)

A thin Kotlin extension layer over the Java MetaObjects engine. No forking, no reimplementation — just idiomatic Kotlin syntax on top of the existing Java API.

Dependency

<dependency>
<groupId>com.metaobjects</groupId>
<artifactId>metaobjects-metadata-ktx</artifactId>
<version>${project.version}</version>
</dependency>

Loading metadata

importcom.metaobjects.metadata.ktx.*importjava.nio.file.Path// From classpath resourcesval loader = loadResources("demo", listOf("meta.demo.json"))
// From a directoryval dirLoader = loadDirectory("app", Path.of("./metadata"))
// From an inline string (defaults to JSON; pass MetaDataFormat.YAML for YAML)val inlineLoader = loadString("test", """{ "metadata.root": { "package": "x", "children": [] } }""")

Navigating metadata

importcom.metaobjects.field.StringField// Null-returning lookups (idiomatic Kotlin)val author = loader.metaObjectOrNull("acme::demo::Author") // null if not found// Reified typed field accessval name = author?.field<StringField>("name") // null if absent or wrong typeval required = author!!.requireField<StringField>("name") // throws if absent// Typed nullable enumsval rel =... // some MetaRelationshipval cardinality:Cardinality?= rel.cardinalityType // null if absent/unknownval target = rel.targetObjectOrNull // resolved MetaObject or null// Own-only attribute readsval maxLen:String?= field.attrStringOrNull("maxLength")

Template + render (FR-004)

importcom.metaobjects.render.InMemoryProviderval prompt = loader.promptTemplateOrNull("acme::demo::WelcomePrompt")
println(prompt?.payloadRef) // "Author"// Render via the Kotlin buildervalout= render {
template ="Hello {{name}}, welcome!"
payload =mapOf("name" to "Ada")
provider =InMemoryProvider(emptyMap())
}
// out == "Hello Ada, welcome!"// Render via a ref + filesystem providerimportcom.metaobjects.render.FilesystemProviderval rendered = render {
ref ="lobby/welcome"
payload =mapOf("name" to "Bob")
provider =FilesystemProvider(Path.of("./prompts"))
format ="html"
}

Patterns not wrapped (Java works fine from Kotlin)

• Custom MetaObject / MetaField subtypes:class MyType : EntityMetaObject("MyType") — Kotlin subclasses Java directly.
• Custom Provider:class MyProvider : Provider { override fun resolve(reference: String): String? = ... }
• Custom MetaDataSource: same pattern.
• MetaObject / MetaField mutation: the Java mutator API (addChild, addMetaAttribute) reads fine from Kotlin.
• Registry builder: Java's MetaDataRegistry.registerType(MyType::class.java) { def -> def.type(...)... } is already lambda-friendly.

Status

metaobjects-metadata-ktx 7.0.0-SNAPSHOT. Mirrors the metaobjects-omdb-ktx Kotlin facade pattern.