javascript - 通过 GET 发送嵌套对象

Question

我有一个非常基本的模式，其中有另一个名为 Vehicle 的对象

let rentSchema = new Schema({
    code: {
        type: Number
    },
    vehicle: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Vehicle'
    },
    ongoing: {
        type: Boolean,
        default: false
    }
}, {collection: 'RentCollection'});

在 Controller 中查找所有内容

exports.getRent = function (req, res) {
    // Find in the DB
     rentSchema.find({}, function (err, rent) {
        if (err) res.status(400).send(err);

        res.json(rent);
     });
 };

响应以租金数组形式出现，但租金对象中缺少车辆对象。这是为什么？

_id: "5e04c19d0a0a100f58bd64b5"
 __v: 0 
ongoing: false

Answer 1

以下是使其发挥作用的分步说明:

1-) 首先，您需要创建一个模型并将其导出，如下所示:

租金.js

const mongoose = require("mongoose");
const Schema = mongoose.Schema;

let rentSchema = new Schema(
  {
    code: {
      type: Number
    },
    vehicle: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "Vehicle"
    },
    ongoing: {
      type: Boolean,
      default: false
    }
  },
  { collection: "RentCollection" }
);

module.exports = mongoose.model("Rent", rentSchema);

2-) 假设您有以下车辆型号:

车辆.js

const mongoose = require("mongoose");
const Schema = mongoose.Schema;

let vehicleSchema = new Schema(
  {
    name: String
  },
  { collection: "VehicleCollection" }
);

module.exports = mongoose.model("Vehicle", vehicleSchema);

3-) 首先让我们在 VehicleCollection 中创建这样的车辆:

{
    "_id": "5e0f465205515667746fd51a",
    "name": "Vehicle 1",
    "__v": 0
}

4-) 然后让我们使用此车辆 ID 在 RentCollection 中创建一个租赁文档，如下所示:

{
    "ongoing": false,
    "_id": "5e0f46b805515667746fd51d",
    "code": 1,
    "vehicle": "5e0f465205515667746fd51a",
    "__v": 0
}

5-) 现在我们可以使用下面的代码，到populate车辆与租金。

const Rent = require("../models/rent"); //todo: change to path to the rent.js

exports.getRent = function(req, res) {
  Rent.find({})
    .populate("vehicle")
    .exec(function(err, rent) {
      if (err) {
        res.status(500).send(err);
      } else {
        if (!rent) {
          res.status(404).send("No rent found");
        } else {
          res.json(rent);
        }
      }
    });
};

6-) 结果将是:

[
    {
        "ongoing": false,
        "_id": "5e0f46b805515667746fd51d",
        "code": 1,
        "vehicle": {
            "_id": "5e0f465205515667746fd51a",
            "name": "Vehicle 1",
            "__v": 0
        },
        "__v": 0
    }
]