[3.6.5] - Custom Schema Hooks / graphql-java-datetime

[rowi1de]

Using https://github.com/donbeave/graphql-java-datetime

import com.zhokhov.graphql.datetime.GraphQLLocalDate
import com.zhokhov.graphql.datetime.GraphQLLocalDateTime
import graphql.language.StringValue
import graphql.schema.Coercing
import graphql.schema.CoercingParseValueException
import graphql.schema.CoercingSerializeException
import graphql.schema.GraphQLScalarType
import graphql.schema.GraphQLType
import org.springframework.stereotype.Component
import java.time.LocalDate
import java.time.LocalDateTime
import java.time.Period
import javax.money.CurrencyUnit
import javax.money.Monetary
import kotlin.reflect.KClass
import kotlin.reflect.KType

@Component
class CustomSchemaGeneratorHooks : SchemaGeneratorHooks {

    override fun willGenerateGraphQLType(type: KType): GraphQLType? = when (type.classifier as? KClass<*>) {
        LocalDateTime::class -> GraphQLLocalDateTime()
        LocalDate::class ->  GraphQLLocalDate()
        CurrencyUnit::class -> currencyUnit
        Period::class -> periodType
        else -> null
    }

Leads to the following exception on startup:

Caused by: graphql.AssertException: All types within a GraphQL schema must have unique names. No two provided types may have the same name.
No provided type may have a name which conflicts with any built in types (including Scalar and Introspection types).
You have redefined the type 'LocalDate' from being a 'GraphQLLocalDate' to a 'GraphQLLocalDate'

Workaround:

 private val _localDateTimeType = object : GraphQLLocalDateTime() {
        override fun hashCode(): Int = Objects.hash(name)

        override fun equals(other: Any?): Boolean = Objects.equals(this.hashCode(), other.hashCode())
    }

    private val _localDateType = object : GraphQLLocalDate() {
        override fun hashCode(): Int = Objects.hash(name)

        override fun equals(other: Any?): Boolean = Objects.equals(this.hashCode(), other.hashCode())
    }

    /**
     * Workaround to prevent duplicate registration
     */
    val localDateTimeType: GraphQLScalarType =
        GraphQLScalarType.Builder()
            .name("LocalDateTime")
            .description(LocalDateTime::class.qualifiedName)
            .coercing(_localDateTimeType.coercing)
            .build()

    /**
     * Workaround to prevent duplicate registration
     */
    val localDateType: GraphQLScalarType =
        GraphQLScalarType.Builder()
            .name("LocalDate")
            .description(LocalDate::class.qualifiedName)
            .coercing(_localDateType.coercing)
            .build()

[dariuszkuc]

Hello 👋

As you noticed, underlying issue is due to the fact that graphql-java types do not implement hashcode/equals so if you try to add the same type twice it will blow up. I haven't looked too deep into the linked graphql-java-datetime library but it looks like it has autoconfiguration that will attempt to automatically register those extended scalars which in turn conflicts with your schema hook declaration.

Since in order to generate the the valid schema you need to explicitly provide those mappings in the hooks, I believe that if you disable the graphql-java-datetime autoconfiguration class it should work as well.

[rowi1de]

Workes with 4.0.0 now