CODEWITHSUNDEEP
javaspring-bootgraphqlgraphql-javatypegraphql
user15793405
user15793405

Reputation:

How to specify DateTime in GraphQL schema?

I am building my GraphQL schema for my project and one of my models has a DateTime format.

How do I write out date formats on my GraphQL schema?

I tried DateTime or Date but nothing shows up.

This is the model:

public Integer Id;
public String name;
public String description;
public LocalDate birthDate;

This is what's in my GraphQL schema:

type Pet {
    id: ID!
    name: String!
    description: String
    birthDate: DateTime
}

But it says:

Unknown type DateTime

Upvotes: 0

Views: 7811

Answers (1)

Hantsy
Hantsy

Reputation: 9261

Create a custom scalar for your types that is not recognized by your framework.

I am not sure which graphql-java based framework you are using. I assume you are using the official Spring for GraphQL from Spring team.

  1. Create a custom scalar, eg my LocalDateTime scalar.
public class LocalDateTimeScalar implements Coercing<LocalDateTime, String> {
    @Override
    public String serialize(Object dataFetcherResult) throws CoercingSerializeException {
        if (dataFetcherResult instanceof LocalDateTime) {
            return ((LocalDateTime) dataFetcherResult).format(DateTimeFormatter.ISO_DATE_TIME);
        } else {
            throw new CoercingSerializeException("Not a valid DateTime");
        }
    }

    @Override
    public LocalDateTime parseValue(Object input) throws CoercingParseValueException {
        return LocalDateTime.parse(input.toString(), DateTimeFormatter.ISO_DATE_TIME);
    }

    @Override
    public LocalDateTime parseLiteral(Object input) throws CoercingParseLiteralException {
        if (input instanceof StringValue) {
            return LocalDateTime.parse(((StringValue) input).getValue(), DateTimeFormatter.ISO_DATE_TIME);
        }

        throw new CoercingParseLiteralException("Value is not a valid ISO date time");
    }
}
  1. Register it in your custom RuntimeWiring bean, check here.
public class Scalars {

    public static GraphQLScalarType localDateTimeType() {
        return GraphQLScalarType.newScalar()
                .name("LocalDateTime")
                .description("LocalDateTime type")
                .coercing(new LocalDateTimeScalar())
                .build();
    }
}

@Component
@RequiredArgsConstructor
public class PostsRuntimeWiring implements RuntimeWiringConfigurer {
    private final DataFetchers dataFetchers;

    @Override
    public void configure(RuntimeWiring.Builder builder) {
        builder
                //...
                .scalar(Scalars.localDateTimeType())
                //...
                .build();
    }
}

If you are using Scalars in other graphql-java based frameworks(GraphQL Java, GraphQL Java Kickstart, GraphQL Kotlin, GraphQL SPQR, Netflix DGS etc) and spring integrations, check my Spring GraphQL Sample. The back-end principle is similar, just some different config.

Upvotes: 2

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