自定义标量

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import { GraphQLScalarType, Kind } from 'graphql';
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const dateScalar = new GraphQLScalarType({
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  name: 'Date',
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  description: 'Date custom scalar type',
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  serialize(value) {
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    if (value instanceof Date) {
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      return value.getTime(); // Convert outgoing Date to integer for JSON
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    }
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    throw Error('GraphQL Date Scalar serializer expected a `Date` object');
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  },
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  parseValue(value) {
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    if (typeof value === 'number') {
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      return new Date(value); // Convert incoming integer to Date
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    }
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    throw new Error('GraphQL Date Scalar parser expected a `number`');
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  },
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  parseLiteral(ast) {
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    if (ast.kind === Kind.INT) {
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      // Convert hard-coded AST string to integer and then to Date
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      return new Date(parseInt(ast.value, 10));
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    }
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    // Invalid hard-coded value (not an integer)
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    return null;
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  },
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});

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import { ApolloServer } from '@apollo/server';
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import { startStandaloneServer } from '@apollo/server/standalone';
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import { GraphQLScalarType, Kind } from 'graphql';
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const typeDefs = `#graphql
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/* highlight-line */  scalar Date
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  type Event {
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    id: ID!
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    date: Date!
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  }
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  type Query {
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    events: [Event!]
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  }
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`;
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const dateScalar = new GraphQLScalarType({
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  // See definition above
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});
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const resolvers = {
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  Date: dateScalar,
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  // ...other resolver definitions...
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};
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const server = new ApolloServer({
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  typeDefs,
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  resolvers,
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});
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const { url } = await startStandaloneServer(server);
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console.log(`🚀 Server listening at: ${url}`);

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import { ApolloServer } from '@apollo/server';
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import { startStandaloneServer } from '@apollo/server/standalone';
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import { GraphQLScalarType, Kind, GraphQLError } from 'graphql';
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// Basic schema
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const typeDefs = `#graphql
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  scalar Odd
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  type Query {
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    # Echoes the provided odd integer
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    echoOdd(odd: Odd!): Odd!
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  }
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`;
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// Validation function for checking "oddness"
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function oddValue(value: unknown) {
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  if (typeof value === 'number' && Number.isInteger(value) && value % 2 !== 0) {
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    return value;
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  }
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  throw new GraphQLError('Provided value is not an odd integer', {
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    extensions: { code: 'BAD_USER_INPUT' },
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  });
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}
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const resolvers = {
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  Odd: new GraphQLScalarType({
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    name: 'Odd',
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    description: 'Odd custom scalar type',
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    parseValue: oddValue,
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    serialize: oddValue,
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    parseLiteral(ast) {
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      if (ast.kind === Kind.INT) {
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        return oddValue(parseInt(ast.value, 10));
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      }
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      throw new GraphQLError('Provided value is not an odd integer', {
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        extensions: { code: 'BAD_USER_INPUT' },
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      });
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    },
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  }),
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  Query: {
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    echoOdd(_, { odd }) {
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      return odd;
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    },
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  },
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};
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const server = new ApolloServer({
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  typeDefs,
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  resolvers,
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});
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const { url } = await startStandaloneServer(server);
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console.log(`🚀 Server listening at: ${url}`);