Question

我有两个文档：

Category = new Schema({
  storeKey: { type: String, required: true },
  cod: { type: String, required: true },
  name: { type: String, required: true },
  visible: { type: Boolean }
},
  {
    timestamps: {
      createdAt: "created",
      updatedAt: "updated"
    }
  }

);

和：

Product = new Schema({
        name: { type: String, required: true },
        cod: String,
        storeKey: { type: String, required: true },
        categoryId: String,
        description: { type: String, required: true },
        price: { type: Number, required: true },
        stockQuantity: { type: Number, required: true },
        avatar: String,
        visible: Boolean
    }, {
            timestamps: true
        });

查询服务器猫鼬以找到具有聚合类别的产品

Product.aggregate([
        {
            $lookup: {
                from: "Category",
                localField: "categoryId",
                foreignField: "_id",
                as: "category"
            }
        }]
    ).exec((error, done) => {
        if (error) res.status(500).send({
            message: langs[req.query.lang],
            error
        });

        res.status(200).send(done);
    });

在本地终端上查询

db.Product.aggregate(
        [{
            $lookup: {
                localField: "categoryId",
                from: "Category",
                foreignField: "_id",
                as: "category"
            }
        }])

在终端中，$ lookup可以正常工作。对于猫鼬，它将带来重复的记录，并且不会带来现有的类别。怎么了？

Answer 1

@Anthony Winzlet是正确的，应该是categories（在pural中）必须离开category（在pural中）而不是ObjectId，但是，我没有定义categoryId字段在产品架构中为ObjectId，因此它正在将字符串与const ProductSchema = new Schema({ name: { type: String, required: true }, cod: String, storeKey: { type: String, required: true }, categoryId: { type: Schema.Types.ObjectId, ref: 'categories' }, description: { type: String, required: true }, price: { type: Number, required: true }, stockQuantity: { type: Number, required: true }, avatar: String, visible: Boolean }, { timestamps: true });进行比较。在终端的测试中，我保存了服务器返回值，该返回值将_id字段作为字符串返回。现在可以了。谢谢！

select rules[1] as rule_1, 
       rules[2] as rule_2,
       rules[3] as rule_3,
       rules[4] as rule_4,
       rules[5] as rule_5,
       rules[6] as rule_6
from (
  select string_to_array(rules, '|') as rules
  from rulebook
) t

$ lookup在MongoDB中工作，但在猫鼬中工作

1 个答案: