JavaScript中不兼容的“长”类型

Question

背景：我们的产品老式后端完全用Java编写。我们正在尝试为其实现GraphQL功能，以便新的基于React的前端可以在需要时从那里获取信息。

以下GraphQL查询返回有关实物投资组合的信息，并且在GraphiQL实例中运行良好。

query Fund($portfolioId: Long) {
    fund: portfolio(id: $portfolioId) {
      id
      fundName: name      
    }
  }

问题：该查询在React中不起作用（使用Apollo Client）。问题似乎在于期望Long类型，而不是number或string。

是否有一种方法可以解决此问题，而无需更改后端的架构？

Answer 1

Long不是GraphQL参考规范的内置标量类型。您必须编写自己的自定义标量解析器。这是一个实现https://github.com/chadlieberman/graphql-type-long/

var GraphQLLong, GraphQLScalarType, Kind, MAX_LONG, MIN_LONG, coerceLong, parseLiteral;

GraphQLScalarType = require('graphql').GraphQLScalarType;

Kind = require('graphql/language').Kind;

MAX_LONG = Number.MAX_SAFE_INTEGER;

MIN_LONG = Number.MIN_SAFE_INTEGER;

coerceLong = function(value) {
  var num;
  if (value === '') {
    throw new TypeError('Long cannot represent non 52-bit signed integer value: (empty string)');
  }
  num = Number(value);
  if (num === num && num <= MAX_LONG && num >= MIN_LONG) {
    if (num < 0) {
      return Math.ceil(num);
    } else {
      return Math.floor(num);
    }
  }
  throw new TypeError('Long cannot represent non 52-bit signed integer value: ' + String(value));
};

parseLiteral = function(ast) {
  var num;
  if (ast.kind === Kind.INT) {
    num = parseInt(ast.value, 10);
    if (num <= MAX_LONG && num >= MIN_LONG) {
      return num;
    }
    return null;
  }
};

GraphQLLong = new GraphQLScalarType({
  name: 'Long',
  description: 'The `Long` scalar type represents 52-bit integers',
  serialize: coerceLong,
  parseValue: coerceLong,
  parseLiteral: parseLiteral
});

module.exports = GraphQLLong;