Graphql为猫鼬聚合查询返回空ID [英] Graphql returns null id for mongoose aggregation query

问题描述

Graphql为猫鼬聚合查询返回空ID，但在其他猫鼬查询中也可以使用.

Graphql returns null id for mongoose aggregation query, but works ok other mongoose queries.

这是我的猫鼬图式:

const { Schema } = mongoose;
const ObjectId = Schema.Types.ObjectId;

const productSchema = new Schema({
  _id: ObjectId,
  price: Number
})

const Product = mongoose.model('Product', productSchema, 'Product')

这是我的Graphql模式:

Here is my Graphql schema:

type Product {
    id: ID
    price: String
}

Graphql常规查询:

Graphql normal query:

   context.Product.findOne()

console.log的结果:

Result with console.log:

[ {
    price: 10,    
    _id: 5d7f8efebff791dcd3bb1b69
}]

graphql的结果:

Result with graphql:

 "getSearch": [
      {
        "id": "5d7f8efebff791dcd3bb1b69",
        "price": 10,
  }]

这里一切都很好. 现在问题在于聚合查询:

GraphQL查询:

GraphQL query:

context.Product.aggregate(
          [
            { $sample: { size: 1 } }
          ]
    )

console.log的结果:

Result with console.log:

[ { _id: 5d7f8f23bff791dcd3bb1da3,
    price: 5
}]

使用GraphQL的结果:

Result with GraphQL:

 "test": [
          {
            "id": null",
            "price": 7,
      }]

这里的问题是:

• id为空
• console.log和graphql的响应是不同的对象

推荐答案

MongoDB中的文档通常没有id属性，只有一个_id属性.这显示在您看到的控制台输出中.但是，猫鼬模型实例确实具有id的吸气剂，该吸气剂返回id的值. 从文档中:

Documents in MongoDB normally don't have an id property, just an _id property. This is shown in the console output you're seeing. However, mongoose model instances do have a getter for id that returns the value of id. From the docs:

猫鼬默认情况下为您的每个模式分配一个id虚拟获取器，该返回器将文档_id字段强制转换为字符串，如果是ObjectIds，则返回其hexString.

Mongoose assigns each of your schemas an id virtual getter by default which returns the documents _id field cast to a string, or in the case of ObjectIds, its hexString.

find和findOne之类的方法返回的是模型的实例有这个吸气剂.但是，使用aggregate会导致返回纯JavaScript对象(没有getter).

What's returned by methods like find and findOne are instances of the Model that have this getter. However, using aggregate results in plain JavaScript objects being returned instead (with no getter).

您可以为id字段编写一个解析程序，以从id或_id提取值:

You can write a resolver for the id field to pull the value from either id or _id:

function resolve (parent, args, context, info) {
  return parent.id || parent._id
}

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