com.expedia.graphql.schema.KotlinDataFetcher.kt Maven / Gradle / Ivy

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Code-only GraphQL schema generation for Kotlin

There is a newer version: 0.0.26

package com.expedia.graphql.schema

import com.expedia.graphql.annotations.GraphQLContext
import com.expedia.graphql.schema.hooks.DataFetcherExecutionPredicate
import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
import graphql.schema.DataFetcher
import graphql.schema.DataFetchingEnvironment
import kotlin.reflect.KFunction

private val mapper = jacksonObjectMapper()

/**
 * Custom wrapper for a class and its annotations
 */
data class Parameter(val klazz: Class<*>, val annotations: List)

/**
 * Simple DataFetcher that invokes function on the target object.
 *
 * @param target The target object that performs the data fetching
 * @param fn The Kotlin function being invoked
 * @param args The GraphQL arguments passed to the data fetcher
 */
class KotlinDataFetcher(
    private val target: Any?,
    private val fn: KFunction<*>,
    private val args: Map,
    private val executionPredicate: DataFetcherExecutionPredicate?
) : DataFetcher {

    override fun get(environment: DataFetchingEnvironment): Any? {
        val instance = target ?: environment.getSource()
        return if (null != instance) {
            @Suppress("Detekt.SpreadOperator")
            fn.call(instance, *args.map {
                val name = it.key
                val klazz = it.value.klazz
                val annotations = it.value.annotations

                if (annotations.any { it.annotationClass == GraphQLContext::class }) {
                    environment.getContext()
                } else {
                    val value = mapper.convertValue(environment.arguments[name], klazz)

                    executionPredicate?.execute(value = value, parameter = it.value, argumentName = name, environment = environment) ?: value
                }
            }.toTypedArray())
        } else {
            null
        }
    }
}