我正在尝试在 TypeScript 中实现这个示例:https://www.apollographql.com/docs/apollo-server/schema/custom-scalars#example-the-date-scalar

import { GraphQLScalarType, Kind } from 'graphql';

export const dateScalar = new GraphQLScalarType({
    name: 'Date',
    description: 'Date custom scalar type',
    serialize(value: Date) {
        return value.getTime(); // Convert outgoing Date to integer for JSON
    },
    parseValue(value: number) {
        return new Date(value); // Convert incoming integer to Date
    },
    parseLiteral(ast) {
        if (ast.kind === Kind.INT) {
            // Convert hard-coded AST string to integer and then to Date
            return new Date(parseInt(ast.value, 10));
        }
        // Invalid hard-coded value (not an integer)
        return null;
    },
});

但有一些 TypeScript 错误:

src/graphql-scalars/date-scalar.ts:6:5 - error TS2322: Type '(value: Date) => number' is not assignable to type 'GraphQLScalarSerializer<number>'.
  Types of parameters 'value' and 'outputValue' are incompatible.
    Type '{}' is missing the following properties from type 'Date': toDateString, toTimeString, toLocaleDateString, toLocaleTimeString, and 37 more.

6     serialize(value: Date) {
      ~~~~~~~~~

  node_modules/graphql/type/definition.d.ts:363:3
    363   serialize?: GraphQLScalarSerializer<TExternal>;
          ~~~~~~~~~
    The expected type comes from property 'serialize' which is declared here on type 'Readonly<GraphQLScalarTypeConfig<Date, number>>'

刚接触 TypeScript，无法理解我在哪里(如何)定义(扩展)这些类型？

最佳答案

添加了评论但也找到了解决方案。

我在 tsconfig.json(设置 compilerOptions.strict = true)中打开严格类型检查后遇到了这个错误。您可以禁用严格类型检查或继续阅读使用严格类型检查的解决方案。

serialize 的声明实际上是:

serialize: GraphQLScalarSerializer<TExternal>

GraphQLScalarSerializer 的类型是:

declare type GraphQLScalarSerializer<TExternal> = (
  outputValue: unknown
) => TExternal;

这意味着您的序列化函数不符合定义。应该是:

serialize(value: unknown) {
    return (value as Date).getTime(); // Convert outgoing Date to integer for JSON
}

对于 future 的读者，上面的类型在 npm 包 graphql@16.6.0 中声明

关于typescript - 无法在 Apollo GraphQL 中定义自定义标量，TypeScript 输入有一些问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/74481995/