如何从 mongodb 获取动态创建的模式模型的数据 [英] How to get data from mongodb for dynamically created schema model

问题描述

我正在尝试从 mongodb 获取数据，但没有.因为下面的错误是原因.我通过动态创建模式模型将数据插入到mongodb中.所以我无法从mongodb获取数据.如何从mongodb获取数据以进行(动态创建模式)集合?请帮助任何人.我在谷歌搜索过但没有用.

I am trying to get data from mongodb but could not. Because below the error is the reason.I have inserted data into mongodb by dynamically creating schema model.So I am not able to get data from mongodb.How to get data from mongodb for (dynamically creating schema) collection? Please help anyone.I have searched in google but no use.

MissingSchemaError:尚未为模型Tea"注册架构.在 Mongoose.model 使用 mongoose.model(name, schema)

MissingSchemaError: Schema hasn't been registered for model "Tea". Use mongoose.model(name, schema) at Mongoose.model

createschema.js

createschema.js

const db = mongoose.createConnection(
     "mongodb://localhost:27017/products", {
         useNewUrlParser: true,
         useUnifiedTopology: true
     }
 );

 function dynamicModel(suffix) {
     var collsName = suffix.charAt(0).toUpperCase() + suffix.slice(1);
     var collsSmall = suffix.toLowerCase();
     var newSchema = new Schema({
         pid: {
             type: String
         },
         product_name: {
             type: String
         },
         product_price: {
             type: Number
         } 
     }, {
         versionKey: false,
         collection: collsSmall
     });
     try {
         if (db.model(collsName)) return db.model(collsName);
     } catch (e) {
         if (e.name === 'MissingSchemaError') {
             return db.model(collsName, newSchema, collsSmall);
         }
     }
 }

 module.exports = dynamicModel;

data.controller.js:

data.controller.js:

const mongoose = require('mongoose');
module.exports.getCollectionData = (req, res, next) => {
    let collection = req.query.collection;
    let tabledata = mongoose.model(collection); //Got MissingSchemaError  
    tabledata.find({}, function(err, docs) {
        if (err) {
            console.log(err);
            return;
        } else {
            res.json({ data: docs, success: true, msg: 'Products data loaded.' });
        }
    })
}

//Create model
module.exports.newCollection = (req, res, next) => {
    var collectionName = req.query.collectionName;
    var NewModel = require(path.resolve('./models/createschema.model.js'))(collectionName);           
    NewModel.create({ }, function(err, doc) {});
}

db.js:

const mongoose = require('mongoose'); 
mongoose.connect(process.env.MONGODB_URI, (err) => {
    if (!err) { console.log('MongoDB connection succeeded.'); } else { console.log('Error in MongoDB connection : ' + JSON.stringify(err, undefined, 2)); }
}); 
require('./createschema.model');

api 调用:

     http://localhost:3000/api/getCollectionData?collection='Tea'

推荐答案

1. 你从根本上滥用了 mongoose.model()/connection.model().

这个函数只能用于创建一个新的猫鼬模型，使用必需的模型名称和架构定义参数.

This function can ONLY be used to CREATE a NEW mongoose model using required model name and schema deffinition parameters.

在 createschema.js 中，当你有 try {if (db.model(collsName))return db.model(collsName);} catch 你不是在检查模型已经存在.db.model(collsName) 总是会抛出错误因为您没有为架构提供第二个必需参数定义.

In createschema.js when you have try {if (db.model(collsName)) return db.model(collsName);} catch you are NOT checking if model already exists. db.model(collsName) will always throw an error because you are not providing second required parameter with schema definition.

我想您正在尝试检查模型是否已经存在，如果存在把它返还.请参阅文档连接.原型.模型.上面的片段应该因此是:

I presume you are trying to check if model already exists and if so return it. Please see documentation for Connection.prototype.models. the fragment above should therefore be:

try {
   // db is an instance of mongoose.Connection    
   let existingModel = db.models[collsName];   
   if (existingModel) return existingModel; 
} catch 

1. 同样在 data.controller.js getCollectionData 当前你是调用一个方法来创建一个新的猫鼬模型 'mongoose.model()',但不要提供架构(因此您会收到 MissingSchemaError)

1. Likewise in data.controller.js getCollectionData currently you are calling a method to create a new mongoose model 'mongoose.model()', but don't provide a schema (hence why you get MissingSchemaError)

你需要要么

• 从猫鼬实例中获取模型(如果您似乎暗示已经注册了)

let tabledata = mongoose.connection.models[collection];

或

• 创建一个新的猫鼬模型

const dynamicModel = require('./createschema.js');
let tabledata =
dynamicModel(collection)

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