Date and Json in type definition for graphql - graphql

Question

Is it possible to have a define a field as Date or JSON in my graphql schema ?
type Individual {
id: Int
name: String
birthDate: Date
token: JSON
}
actually the server is returning me an error saying :
Type "Date" not found in document.
at ASTDefinitionBuilder._resolveType (****node_modules\graphql\utilities\buildASTSchema.js:134:11)
And same error for JSON...
Any idea ?

Answer 1

Have a look at custom scalars: https://www.apollographql.com/docs/graphql-tools/scalars.html
create a new scalar in your schema:
scalar Date
type MyType {
created: Date
}
and create a new resolver:
import { GraphQLScalarType } from 'graphql';
import { Kind } from 'graphql/language';
const resolverMap = {
Date: new GraphQLScalarType({
name: 'Date',
description: 'Date custom scalar type',
parseValue(value) {
return new Date(value); // value from the client
},
serialize(value) {
return value.getTime(); // value sent to the client
},
parseLiteral(ast) {
if (ast.kind === Kind.INT) {
return parseInt(ast.value, 10); // ast value is always in string format
}
return null;
},
})
};

Answer 2

Primitive scalar types in GraphQL are Int, Float, String, Boolean and ID. For JSON and Date you need to define your own custom scalar types, the documentation is pretty clear on how to do this.
In your schema you have to add:
scalar Date
type MyType {
created: Date
}
Then, in your code you have to add the type implementation:
import { GraphQLScalarType } from 'graphql';
const dateScalar = new GraphQLScalarType({
name: 'Date',
parseValue(value) {
return new Date(value);
},
serialize(value) {
return value.toISOString();
},
})
Finally, you have to include this custom scalar type in your resolvers:
const server = new ApolloServer({
typeDefs,
resolvers: {
Date: dateScalar,
// Remaining resolvers..
},
});
This Date implementation will parse any string accepted by the Date constructor, and will return the date as a string in ISO format.
For JSON you might use graphql-type-json and import it as shown here.