How to get data from mongodb for dynamically created schema model - node.js

Question

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: Schema hasn't been registered for model "Tea".
Use mongoose.model(name, schema) at Mongoose.model
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:
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 call:
http://localhost:3000/api/getCollectionData?collection='Tea'

Answer 1

Try db.model instead of mongoose.model in function getCollectionData
Since you created the collection on that particular connection, you have to use the same connection to get the model as well.
const db = mongoose.createConnection(
"mongodb://localhost:27017/products", {
useNewUrlParser: true,
useUnifiedTopology: true
}
);
module.exports.getCollectionData = (req, res, next) => {
let collection = req.query.collection;
let tabledata = db.model(collection); //Change here
tabledata.find({}, function(err, docs) {
if (err) {
console.log(err);
return;
} else {
res.json({ data: docs, success: true, msg: 'Products data loaded.' });
}
})
}

Answer 2

You fundamentally misuse mongoose.model() / connection.model().
This function can ONLY be used to CREATE a NEW mongoose model using
required model name and schema deffinition parameters.
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.
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
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)
you need to EITHER
get the model from mongoose instance (if already registered as you seem to imply)
let tabledata = mongoose.connection.models[collection];
OR
create a new mongoose model
const dynamicModel = require('./createschema.js');
let tabledata =
dynamicModel(collection)