如何在graphql解析器中同时返回错误和数据? [英] How to return both error and data in a graphql resolver?

问题描述

我正在考虑实现同时包含错误和数据的graphql响应的方法.

I was thinking about ways of implementing graphql response that would contain both an error and data.

是否可以在不创建包含error的类型的情况下这样做?

Is it possible to do so without creating a type that would contain error?

例如

突变addMembersToTeam(membersIds: [ID!]! teamId: ID!): [Member]将成员添加到某个团队.假设使用以下membersIds:[1, 2, 3]来调用此突变.

Mutation addMembersToTeam(membersIds: [ID!]! teamId: ID!): [Member] adds members to some team. Suppose this mutation is called with the following membersIds: [1, 2, 3].

具有ID 1和2的成员已经在团队中，因此必须抛出一个错误，即不能添加这些成员，但是应该添加ID 3的成员，因为他不在团队中.

Members with ids 1 and 2 are already in the team, so an error must be thrown that these members cannot be added, but member with an id 3 should be added as he is not in the team.

我当时正在考虑使用formatResponse，但似乎那里没有错误.

I was thinking about using formatResponse but seems that I can't get an error there.

是否可以在不将错误字段添加到返回类型的情况下解决此问题?

Is it possible to solve this problem without adding error field to the return type?

推荐答案

是否可以在不将错误字段添加到返回类型的情况下解决此问题?

Is it possible to solve this problem without adding error field to the return type?

不幸的是，没有.

解析器可以返回数据，也可以返回null并引发错误.它不能两者兼而有之.为了澄清，有可能得到部分响应和一些错误.一个简单的例子:

A resolver can either return data, or return null and throw an error. It cannot do both. To clarify, it is possible to get a partial response and some errors. A simple example:

const typeDefs = `
  type Query {
    foo: Foo
  }

  type Foo {
    a: String
    b: String
  }
`
const resolvers = {
  Query: {
    foo: () => {},
  }
  Foo: {
    a: () => 'A',
    b: () => new Error('Oops!'),
  }
}

在此示例中，查询foo上的两个字段将导致以下响应:

In this example, querying both fields on foo will result in the following response:

{
  "data": {
    "foo": {
      "a": "A",
      "b": null
    }
  },
  "errors": [
    {
      "message": "Oops",
      "locations": [
        {
          "line": 6,
          "column": 5
        }
      ],
      "path": [
        "foo",
        "b"
      ]
    }
  ]
}

通过这种方式，可以同时发送数据和错误.但是您不能在相同的领域中这样做，就像您的问题一样.有两种解决方法.如您所指出的，您可以将错误作为响应的一部分返回，通常是这样做的.然后，您可以使用formatResponse，遍历结果数据，提取任何错误，并将其与其他GraphQL错误一起组合.并非最佳选择，但它可能会为您提供所需的行为.

In this way, it's possible to send back both data and errors. But you cannot do so for the same field, like in your question. There's a couple of ways around this. As you point out, you could return the errors as part of the response, which is usually how this is done. You could then use formatResponse, walk the resulting data, extract any errors and combine them with them with any other GraphQL errors. Not optimal, but it may get you the behavior you're looking for.

另一种选择是修改突变，使其采用单个memberId.然后，您可以为要添加的每个ID请求单独的突变:

Another alternative is to modify the mutation so it takes a single memberId. You can then request a separate mutation for each id you're adding:

add1: addMemberToTeam(memberId: $memberId1 teamId: $teamId): {
  id
}
add2: addMemberToTeam(memberId: $memberId2 teamId: $teamId): {
  id
}
add3: addMemberToTeam(memberId: $memberId3 teamId: $teamId): {
  id
}

这可能在处理客户端时比较棘手，当然效率较低，但同样可能使您获得预期的行为.

This can be trickier to handle client-side, and is of course less efficient, but again might get you the expected behavior.

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