Express : Does mysql queries in app.js make sense

Question

Does app.js get processed only once?. In that case, does it make sense to run setup queries in app.js so that I don't have to run it on every request?.

I have a table to countries and regions that I need in several requests.

I am looking at an implementation something like this https://stackoverflow.com/a/21133217/406659

Answer 1

No putting this in app.js does not make sense. I would create a models folder and encapsulate all of your database logic in a module within that folder. Then on startup of the app (ie on app.listen() callback) I would call a method from that module which does the setup for me. For example:

Some DB module in models

module.exports = {
   setup: () => {
    // Set up logic here - checking if tables exist etc
   }
}

Then in app.js or equal

require <SOME DB MODULE>

app.listen(<PORT>, () => {
   <SOME DB MODULE>.setup();
})

Note this is a generalised approach as I don't know the specifics of your setup - This approach just ensures encapsulated and reusable code. I've also used ES6 syntax where possible.

Hope this helps

Dylan