graphql，联合标量类型? [英] graphql, union scalar type?

问题描述

payload字段可以是Int或String标量类型. 当我将其写为联合体类型时:

The payload field can be Int or String scalar type. when I write it like union type:

const schema = `
  input QuickReply {
    content_type: String
    title: String
    payload: Int | String
    image_url: String
  }
`

我遇到一个错误:

GraphQLError: Syntax Error GraphQL request (45:18) Expected Name, found |

    44:     title: String
    45:     payload: Int | String
                         ^
    46:     image_url: String

GraphQL似乎不支持联合标量类型.

It seems GraphQL does not support union scalar type.

那么，我该如何解决这种情况?

So, how can I solve this situation?

推荐答案

标量不能用作并集的一部分，因为根据规范，并集明确地表示一个对象，该对象可能是GraphQL对象类型的列表之一."相反，您可以使用自定义标量.例如:

Scalars can't be used as part of unions, since per the specification, unions specifically "represent an object that could be one of a list of GraphQL Object types." Instead, you can use a custom scalar. For example:

const MAX_INT = 2147483647
const MIN_INT = -2147483648
const coerceIntString = (value) => {
  if (Array.isArray(value)) {
    throw new TypeError(`IntString cannot represent an array value: [${String(value)}]`)
  }
  if (Number.isInteger(value)) {
    if (value < MIN_INT || value > MAX_INT) {
      throw new TypeError(`Value is integer but outside of valid range for 32-bit signed integer: ${String(value)}`)
    }
    return value
  }
  return String(value)
}
const IntString = new GraphQLScalarType({
  name: 'IntString',
  serialize: coerceIntString,
  parseValue: coerceIntString,
  parseLiteral(ast) {
    if (ast.kind === Kind.INT) {
      return coerceIntString(parseInt(ast.value, 10))
    }
    if (ast.kind === Kind.STRING) {
      return ast.value
    }
    return undefined
  }
})

此代码有效地组合了Int和String类型的行为，同时仍强制使用32位带符号整数的范围.但是，您可以具有所需的任何类型强制行为.查看源代码，以了解如何内置标量工作，或

This code effectively combines the behaviors for both the Int and String types, while still enforcing the range for 32-bit signed integers. However, you could have whatever type coercion behavior you want. Check out the source code to see how the built-in scalars work, or this article for more details around how custom scalars work.

请注意，如果您要为 output 字段返回多个标量之一，则可以对 parent 类型使用并集来获得相似的结果.例如，这是不可能的:

Note that if you're trying to return one of several scalars for an output field, it's possible to utilize a union for the parent type to achieve a similar result. For example, this isn't possible:

type Post {
  content: String | Int
}

但是您可以执行以下操作:

but you can do the following:

type PostString {
  content: String
}

type PostInt {
  content: Int
}

union Post = PostString | PostInt

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