Configuration

Configure Metalastic metamodel generation using the type-safe Gradle plugin DSL or manual KSP configuration.

Understanding What Gets Generated

Before configuring Metalastic, it's important to understand what artifacts are generated and how configuration affects them.

Two Types of Generated Artifacts

Metalastic generates two distinct types of files:

1. Individual Metamodel Classes

One class per @Document annotated class:

Source Document                    Generated Metamodel
────────────────────────────────  ─────────────────────────────────
com.example.domain.Product    →   com.example.domain.MetaProduct
com.example.domain.Category   →   com.example.domain.MetaCategory
com.example.domain.Review     →   com.example.domain.MetaReview

Key points:

• ✅ Stay in the same package as the source document
• ✅ Named with configurable prefix (default: "Meta")
• ✅ Controlled by classPrefix configuration

2. Centralized Registry Class

One registry class per source set containing all metamodel references:

Generated Registry
──────────────────────────────────────────
com.example.search.Metamodels

object Metamodels {
    fun entries(): Sequence<Document<*>> = sequenceOf(
        product,   // from MetaProduct.Companion
        category,  // from MetaCategory.Companion
        review     // from MetaReview.Companion
    )
}

Key points:

• ✅ Package controlled by packageName configuration
• ✅ Class name controlled by registryClassName configuration
• ✅ One registry per source set (main, test, etc.)

Configuration Properties

Quick Reference Table

Property	Controls	Applies To	Default	Example
packageName	Package of registry class	Metamodels registry only	Auto-detected, fallback: "com.ekino.oss.metalastic"	"com.example.search"
registryClassName	Name of registry class	Metamodels registry only	"Metamodels"	"MainMetamodels"
classPrefix	Prefix for Meta classes*	All document metamodels	"Meta"	"Models"

Important

registryClassName only controls the centralized registry class name, not individual document metamodel names. Use classPrefix to control document class prefixes (MetaProduct, MetaCategory, etc.).

Detailed Property Explanations

packageName

Controls: Package of the centralized Metamodels registry class

metalastic {
    metamodels {
        packageName = "com.example.search.metamodels"
    }
}

Generates:

// File: com/example/search/metamodels/Metamodels.kt
package com.example.search.metamodels

object Metamodels {
    fun entries(): Sequence<Document<*>> = ...
}

Auto-detection behavior:

If not explicitly configured, packageName is determined by:

1. Single package: If all @Document classes are in one package → use that package
2. Multiple packages: Find common ancestor package
   • Example: com.example.domain + com.example.model → com.example
3. No common ancestor or empty: Fallback to "com.ekino.oss.metalastic"

Individual Meta classes:* Stay in their original document packages (NOT affected by this setting)

registryClassName

Controls: Name of the centralized Metamodels registry class

metalastic {
    metamodels {
        registryClassName = "MainMetamodels"
    }
}

Generates:

object MainMetamodels {  // ← Name controlled by registryClassName
    fun entries(): Sequence<Document<*>> = ...
}

Individual Meta classes:* NOT affected (use classPrefix instead)

classPrefix

Controls: Prefix added to all generated document metamodel class names

metalastic {
    metamodels {
        classPrefix = "Models"
    }
}

Generates:

Product    → ModelsProduct
Category   → ModelsCategory
Review     → ModelsReview

Default is "Meta" (MetaProduct, MetaCategory, etc.)

Basic Configuration

Simple Single Source Set

For projects with just a main source set:

plugins {
    id("com.google.devtools.ksp") version "2.3.3"
    id("com.ekino.oss.metalastic") version "1.1.0"
}

metalastic {
    metamodels {
        packageName = "com.example.search"
        registryClassName = "Metamodels"
        classPrefix = "Meta"  // default, can be omitted
    }
}

Generates:

• Registry: com.example.search.Metamodels
• Documents: com.example.domain.MetaProduct, etc. (in their original packages)

Multi-Source Set Configuration

For projects with main, test, and custom source sets:

metalastic {
    metamodels {
        // Global defaults (apply to all source sets unless overridden)
        classPrefix = "Meta"

        // Main source set specific
        main {
            packageName = "com.example.main.search"
            registryClassName = "MainMetamodels"
        }

        // Test source set specific
        test {
            packageName = "com.example.test.search"
            registryClassName = "TestMetamodels"
        }

        // Custom source set (use sourceSet syntax)
        sourceSet("integration") {
            packageName = "com.example.integration.search"
            registryClassName = "IntegrationMetamodels"
        }
    }
}

Generates:

• Main registry: com.example.main.search.MainMetamodels
• Test registry: com.example.test.search.TestMetamodels
• Integration registry: com.example.integration.search.IntegrationMetamodels
• All document classes: Use Meta prefix (inherited from global classPrefix)

Source Set Configuration

Pre-defined Source Sets

Metalastic provides convenient accessors for common source sets:

metalastic {
    metamodels {
        main {
            // Main application code
        }

        test {
            // Unit tests
        }

        // Integration test variants
        integration {
            // Integration tests
        }

        integrationTest {
            // Alternative naming
        }

        // Functional test variants
        functional {
            // Functional tests
        }

        functionalTest {
            // Alternative naming
        }

        // E2E test variants
        e2e {
            // End-to-end tests
        }

        e2eTest {
            // Alternative naming
        }
    }
}

Custom Source Sets

For custom source sets, use the sourceSet() function:

metalastic {
    metamodels {
        sourceSet("contractTest") {
            packageName = "com.example.contract"
            registryClassName = "ContractMetamodels"
        }

        sourceSet("performance") {
            packageName = "com.example.perf"
            registryClassName = "PerformanceMetamodels"
        }
    }
}

Features Configuration

Java Compatibility

Generate @JvmField annotations for seamless Java interoperability:

metalastic {
    features {
        generateJavaCompatibility = true  // default: true
    }
}

When enabled:

@JvmField
val id: KeywordField<String> = keyword("id")

When disabled:

val id: KeywordField<String> = keyword("id")  // No @JvmField

Recommendation: Keep enabled unless you're in a Kotlin-only project and want to reduce annotation clutter.

Private Class Metamodels

Generate metamodels for private @Document classes:

metalastic {
    features {
        generatePrivateClassMetamodels = false  // default: false
    }
}

When disabled (default):

@Document(indexName = "internal")
private class InternalDoc { }  // No MetaInternalDoc generated

When enabled:

@Document(indexName = "internal")
private class InternalDoc { }  // Generates MetaInternalDoc

Recommendation: Keep disabled unless you specifically need metamodels for private classes. Public API is cleaner without them.

Debug Reporting

Enable Processor Reports

Generate detailed markdown reports for debugging and build analysis:

metalastic {
    reporting {
        enabled = true  // default: false
        outputPath = "build/reports/metalastic/processor-report.md"
    }
}

Report includes:

• ⏱️ Performance metrics for each processing phase
• 📊 Generation statistics (documents discovered, fields processed)
• 🔍 Detailed processing log with timestamps
• ❌ Error diagnostics with context
• 📈 Historical tracking across builds

When to use:

• 🐛 Debugging generation issues
• ⚡ Optimizing build performance
• 📊 Understanding what's being generated
• 🚀 Monitoring in CI/CD pipelines

Manual Configuration (Without Gradle Plugin)

If not using the Gradle plugin, configure KSP directly:

plugins {
    id("com.google.devtools.ksp") version "2.3.3"
}

dependencies {
    implementation("com.ekino.oss:metalastic-core:1.1.0")
    ksp("com.ekino.oss:metalastic-processor:1.1.0")
}

ksp {
    // Global configuration
    arg("metamodels.package", "com.example.search")
    arg("metamodels.registryClassName", "Metamodels")
    arg("metamodels.classPrefix", "Meta")

    // Source set specific (use dot notation)
    arg("metamodels.main.package", "com.example.main")
    arg("metamodels.main.registryClassName", "MainMetamodels")

    arg("metamodels.test.package", "com.example.test")
    arg("metamodels.test.registryClassName", "TestMetamodels")

    // Features
    arg("metalastic.generateJavaCompatibility", "true")
    arg("metalastic.generatePrivateClassMetamodels", "false")

    // Reporting
    arg("metalastic.reportingPath", "build/reports/metalastic/report.md")
}

KSP Argument Keys:

Gradle Plugin DSL	KSP Argument Key
metamodels.packageName	metamodels.package
metamodels.registryClassName	metamodels.registryClassName
metamodels.classPrefix	metamodels.classPrefix
metamodels.main.packageName	metamodels.main.package
metamodels.main.registryClassName	metamodels.main.registryClassName
features.generateJavaCompatibility	metalastic.generateJavaCompatibility
features.generatePrivateClassMetamodels	metalastic.generatePrivateClassMetamodels
reporting.enabled + outputPath	metalastic.reportingPath

Complete Configuration Reference

Full Gradle Plugin Configuration

metalastic {
    // Metamodel generation configuration
    metamodels {
        // ────────────────────────────────────────────────────────
        // Global defaults (apply to all source sets)
        // ────────────────────────────────────────────────────────
        packageName = "com.example.search"    // Registry package
        registryClassName = "Metamodels"              // Registry class name
        classPrefix = "Meta"                  // Meta* prefix

        // ────────────────────────────────────────────────────────
        // Source set specific overrides
        // ────────────────────────────────────────────────────────
        main {
            packageName = "com.example.main.search"
            registryClassName = "MainMetamodels"
            classPrefix = "Meta"  // Can override per source set
        }

        test {
            packageName = "com.example.test.search"
            registryClassName = "TestMetamodels"
        }

        // Custom source sets
        sourceSet("integration") {
            packageName = "com.example.integration"
            registryClassName = "IntegrationMetamodels"
        }
    }

    // ────────────────────────────────────────────────────────
    // Feature flags
    // ────────────────────────────────────────────────────────
    features {
        generateJavaCompatibility = true       // @JvmField annotations
        generatePrivateClassMetamodels = false // Skip private classes
    }

    // ────────────────────────────────────────────────────────
    // Debug reporting
    // ────────────────────────────────────────────────────────
    reporting {
        enabled = false  // Enable for debugging
        outputPath = "build/reports/metalastic/processor-report.md"
    }
}

Next Steps

• Understanding Metamodels - Learn how generation works
• Field Types Reference - Explore all supported field types
• Query DSL Guide - Build type-safe queries