Mongoose/NodeJS - Sort button in .EJS template - node.js

Question

In my Mongoose controller I am sorting according to creation date of the product:
let products = await Product.find().sort({ 'createdAt': -1 });
I want to create a button in EJS template which allows the user to select different criteria to sort by (e.g. price). Creating the button itself is no problem, but I don't know how to access the sort function in the controller when an option is selected (e.g. if price selected, sort by price), and where I should be putting the code, in the controller or in the EJS template?
I assume I should be using req.query, but I don't know how. Thanks.

Answer 1

Part One - Abstraction Mongoose API to JS
Mongoose allows you to build your query in sections. Let say you have a function the query Product with additional options object.
findOptions - contains the filter options (the where part of the query)
pagingOptions - contains sorting+ordering,, page and pageSize.
This is all the context you need to build a query.
async function getProducts(findOptions, pagingOptions) {
const query = Product.find(findOptions);
if(pagingOptions.sort) {
// Note: This example assumes that paging.sort has the same structure as Monguse sort object.
query.sort(paging.sort);
}
let products = await query.exec();
...
return products;
}
Usage:
let products = await getProducts({}, { 'createdAt': -1 });
let products = await getProducts({ 'createdAt': { $gt: Date.now() }}, { '_id': 1 });
You can add or restrict many many things using the options object to manage the query context
See: mongoose query doc
Part Two - Exposing an API
Now that we have a method at the server-side that can query the Products using only JS object (JSON) you will need to expose an HTTP API so a client will be able to call the server with his query criteria.
Let defined this is the HTTP API that we will send to the client to integrate with:
POST /products
// request body
{
sort: { FIELD_NAME: ASC|DESC }, // ASC=1, DESC=-1
}
Usage:
curl -X POST -H "Content-Type: application/json" --data '{ sort: { "createdAt": "1" } }' http:localhost:3000
Note: you can extend both the HTTP API and the Backend method options to extend the functionality further.
See the following to check how to implement HTTP endpoint via express
https://expressjs.com/en/guide/routing.html
http://expressjs.com/en/resources/middleware/body-parser.html#bodyparserjsonoptions
Part Three - FrontEnd Integration
Now all is left is to implement an HTTP client and expose the HTTP API so the rest of the FrontEnd modules will be able to call the backend.
The following is a simple fetch example but you can use any HTTP client lib that you like.
const productsEndpoint = baseUrl + '/products';
async function getProducts(options) {
const response = await fetch(productsEndpoint, {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify(options)
});
return response.json();
}
These three steps will you to have a well-defined API across components and the layers within them.