ObjectId 的 Mongoose Schema 默认值答案

【问题标题】：Mongoose Schema default value for ObjectIdObjectId 的 Mongoose Schema 默认值
【发布时间】：2015-11-26 00:35:52
【问题描述】：

我有一系列仓库升级。它是预定义的“模板”集合，包含例如 max_capacity、level 和 price。然后我有warehouse_levels 集合，它包含针对不同存储资源的warehouse_upgrades 的不同索引。但是我不能创建warehouse_level模型，因为我需要加载warehouse_upgrades的_ids

WarehouseUpgrade = mongoose.model("warehouse_upgrade");

// find wheat upgrade containing level 0
WarehouseUpgrade.find({ type: "wheat", level: 0 }).exec(function (err, wheat) {

    var warehouseLevelSchema = Schema({
        wheat: {
            type: Schema.Types.ObjectId,
            ref: "warehouse_upgrade",
            default: wheat._id
        },
        ... more resources
    };
    var WarehouseLevel = mongoose.model("warehouse_level", warehouseLevelSchema);
}

当我想调用 var WarehouseLevel = mongoose.model("warehouse_level");解释此代码会引发错误：

MissingSchemaError: Schema hasn't been registered for model "warehouse_level"

如果我从 WarehouseUpgrade.find 中提取模式定义，那么代码可以工作，但我无法为资源仓库设置默认值。

当我不想硬编码这些值时，如何设置来自不同集合的 ObjectId 的默认值？

编辑：我将所有模式定义加载到名为 mongoose.js 的文件中：

var mongoose            = require("mongoose"),
Animal                  = require("../models/Animal");
Warehouse_upgrade       = require("../models/Warehouse_upgrade"),
Warehouse_level         = require("../models/Warehouse_level"),
User                    = require("../models/User"),
...

module.exports = function(config) {
    mongoose.connect(config.db);
    var db = mongoose.connection;

    // And now I call methods for creating my "templates"
    Warehouse_upgrade.createUpgrades();
    Animal.createAnimals();
    User.createDefaultUser();
}

MissingSchemaError 发生在 model/User(username, hashed_password, email, warehouse_level,...) - 每个用户都引用了自己在 warehouse_level 中的文档。

// User
var mongoose = require("mongoose"),
    Schema = mongoose.Schema,
    Warehouse_level = mongoose.model("warehouse_level");

// There are no users in DB, we need create default ones
// But first, we need to create collection document for warehouse_level
// and warehouse (not shown in this code snippet)
Warehouse_level.create({}, function (err, warehouseLevel) {
    if (err) { console.error(err); return; }
    // warehouse_level document is created, let's create user
    User.create({ username: ..., warehouse_level: warehouseLevel._id });
});

【问题讨论】：

您可能必须在默认键中使用一个对象，例如 default: {
Hi 是 Schema 定义为：var Schema = DB.mongoose.Schema;
var Schema = DB.mongoose.Schema;抛出错误 - 引用错误 - 未定义数据库
那么您是如何定义数据库的，您将数据库附加到何处？ Schema 没有直接定义，只有 mongoose.Schema 存在。

标签： node.js mongodb mongoose schema odm

【解决方案1】：

实现此目的的一种可能方法是创建一个类似“setDefaultIndexes”的方法

var warehouseLevelSchema = mongoose.Schema({..});

warehouseLevelSchema.methods = {
    setDefaultUpgrades: function() {
        var self = this;
        WarehouseUpgrade.find({ level: 0 }).exec(function (err, collection) {
            for (var i = 0; i < collection.length; i++) {
                var upgrade = collection[i];
                self[upgrade.type] = upgrade._id;
            }
            self.save();
        });
    }
};

var Warehouse_level = mongoose.model("warehouse_level", warehouseLevelSchema);

并在创建新的warehouse_level 后调用它：

WarehouseLevel.create({}, function (err, warehouseLevel) {
    if (err) { console.error(err); return; }
    warehouseLevel.setDefaultUpgrades();
});

【讨论】：