Graphql-获取完整的子对象，如果不存在则返回null [英] Graphql - get full sub-object, or null if doesn't exist

问题描述

我有一个graphql查询，它使用Client对象获取一个Meeting对象:

I have a graphql query which gets a Meeting object with Client object:

type Meeting {
  address: String!
  client: Client
}
type Client {
  displayName: String!
}

displayName是必需的，但不是client. 如果我将其查询为

The displayName is required, but client isn't. If I'm querying it as

{
  getMeeting(meetingId: "43bbea6ea0c6112b0abcf11d") {
    address
    client {
      displayName
    }
  }
}

这次会议没有客户，这时我遇到了错误:

And this meeting doesn't have a client, then I'm getting an error:

Error: Cannot return null for non-nullable field Client.displayName.

我只希望有一个客户，我将提供其详细信息.如果没有，我会得到client: null.

I just want that if there is a client, I will get its full details. And if there isn't, I will get client: null.

如果我从displayName中删除了必填项，则在client为null且我得到

If I will remove the required from the displayName, it will work also when client is null and I will get

"client": { "displayName": null }

"client": { "displayName": null }

如我所料.但我仍在寻找一种在displayName上强制执行必需的方法-仅在有客户端的情况下.

as I've expected. But I'm still looking for a way to enforce the required on the displayName - only if there is a client.

在graphql中有什么方法可以做到吗?

Is there any way to do that in graphql?

推荐答案

所以问题出在mongoose上.

当我从数据库中获取数据时，猫鼬会添加client: {}的空嵌入式子文档，即使数据库中meeting文档中没有这样的键(并且console.log(meeting)也不显示此内容)字段-仅console.log(meeting.client)打印client: {}).

When I'm fetching the data from the DB, mongoose adds the empty embedded subdocument of client: {} even if there is no such key in the meeting document in the DB (and console.log(meeting) doesn't show this field - Only console.log(meeting.client) prints client: {}).

因此，graphql尝试返回client的必填字段，因为client不是我所认为的undefined.

Hence graphql tries to return the required field of client, because client is not undefined as I thought.

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