graphql.kickstart.tools.resolver.FieldResolver.kt Maven / Gradle / Ivy

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Tools to help map a GraphQL schema to existing Java objects.

There is a newer version: 14.0.0

package graphql.kickstart.tools.resolver

import graphql.kickstart.tools.*
import graphql.kickstart.tools.GenericType
import graphql.kickstart.tools.ResolverError
import graphql.kickstart.tools.ResolverInfo
import graphql.kickstart.tools.TypeClassMatcher
import graphql.kickstart.tools.util.JavaType
import graphql.language.FieldDefinition
import graphql.schema.DataFetcher
import graphql.schema.DataFetchingEnvironment

/**
 * @author Andrew Potter
 */
internal abstract class FieldResolver(
    val field: FieldDefinition,
    val search: FieldResolverScanner.Search,
    val options: SchemaParserOptions,
    relativeTo: JavaType
) {
    val resolverInfo: ResolverInfo = search.resolverInfo
    val genericType = GenericType(search.type, options).relativeToPotentialParent(relativeTo)

    abstract fun scanForMatches(): List

    abstract fun createDataFetcher(): DataFetcher<*>

    /**
     * Add source resolver depending on whether or not this is a resolver method
     */
    protected fun getSourceResolver(): SourceResolver {
        return if (this.search.source != null) {
            { this.search.source }
        } else {
            { environment ->
                val source = environment.getSource()

                if (!this.genericType.isAssignableFrom(source.javaClass)) {
                    throw ResolverError("Expected source object to be an instance of '${this.genericType.getRawClass().name}' but instead got '${source.javaClass.name}'")
                }

                source
            }
        }
    }
}

internal typealias SourceResolver = (DataFetchingEnvironment) -> Any