hi dev's
While working on a "hospital management system" demo project using rails.I stucked in a scenario where I need to pull "firstname" from users table. Here is detailed scenario ...
So Here are my tables :
table1 : appointments has following columns id|patient_id|physician_id| table2: patients table table3: physicians table id|user_id|... id|user_id|... table4: users (note that users table as 4 types of user admim,patient,physician and nurse )
id|firstname|lastname|role|..... ** Here user_id refers to users table primary key
** patient_id and physician_id refers to patients and physicians primary key
Now how can i fetch "firstname" from users table from appointments table????
As of now i am using following code to print appointments but this is to costly
# frozen_string_literal: true module Admin # Appointment actions class AppointmentsController < ApplicationController before_action :new_user def index @appointments = paginate(fetch_records) respond_to do |format| format.html { @appointments } end end . . . private def fetch_records @appointments = current_user.admin? ? Appointment.all : Appointment.current_user(current_user.physician) @appointments.collect do |appointment| [ appointment.id, appointment.patient.user.firstname, appointment.physician.user.firstname, appointment.status, appointment.appointment_date ] end end end end rails --versin : rails 5.2.3
ruby --version: 2.6.3
Top comments (2)
Did you start by writing a query that gave the results you wanted?
Like:
SELECT firstname
FROM users
WHERE Appointments.patient_id = patients.user_id
AND patients.user_id = user.id
(I do not have all the criteria to write the query you need.)
As your code has no literal SQL, the problem is either your query or your implementation of it in whatever you are writing.
Your query creates an N+1 issue.
Try preloading the associated data: