Database‐Models

Database Schemas & Data Model Definitions

NQTCoder uses four primary MongoDB collections to manage users, coding challenges, submissions, and proctored test sessions.

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1. User Schema (models/User.js)

Stores user profiles, credential hashes, email verification details, and practice stats.

Field Name	Type	Description
username	String (Required, Unique)	User's unique handle.
email	String (Required, Unique)	User's email address (Google or local credentials).
password	String	Bcrypt hash of password (absent for Google OAuth).
role	String ('user' or 'admin')	Access permissions role. Defaults to 'user'.
isVerified	Boolean	Account validation status. Blocked from logging in if false.
otpCode	String	Active 6-digit verification OTP.
otpExpires	Date	Verification OTP timestamp expiration (10 minutes duration).
solvedQuestions	Array [Schema.Types.ObjectId]	List of successfully solved question references.
solvedCount	Object	Counts of solved challenges categorized by difficulty.

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2. Question Schema (models/Question.js)

Holds coding challenge details, constraints, metadata, and the test case arrays.

Field Name	Type	Description
title	String (Required)	The title of the programming challenge.
description	String (Required)	Markdown string outlining problem parameters and instructions.
inputFormat	String	Description of expected standard input formatting.
outputFormat	String	Description of expected console output formatting.
constraints	String	Code constraints (e.g. constraints on execution space or variable sizes).
difficulty	String ('Easy', 'Medium', 'Hard')	Question difficulty category.
topic	String	Tag categorization (e.g. Arrays, Recursion).
company	Array [String]	Recruitment companies using this problem (e.g. TCS, Wipro).
testCases	Array [Object]	Test cases with structure: input (String), output (String), and isPrivate (Boolean). Hidden test cases are marked isPrivate: true.
timerEnabled	Boolean	Enables a countdown timer inside the coding workspace.
timerDuration	Number	Active duration in minutes for the workspace timer.

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3. Submission Schema (models/Submission.js)

Tracks logs of compilations and submissions.

Field Name	Type	Description
user	Schema.Types.ObjectId (Required)	Reference to the submitting user profile.
question	Schema.Types.ObjectId (Required)	Reference to the challenge being solved.
code	String (Required)	Code source text submitted by the user.
language	String ('cpp', 'java', 'python')	Chosen programming language.
status	String	Output verdict (e.g., Accepted, Wrong Answer, Runtime Error, Compilation Error).
runtime	Number	Execution time in milliseconds.
error	String	Detailed compiler console output (if compilation failed).
testCasesPassed	Number	Count of total test cases successfully passed.
totalTestCases	Number	Total test cases compiled against (visible + hidden).

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4. MockTest Schema (models/MockTest.js)

Controls proctored assessments, warning stats, and time-out conditions.

Field Name	Type	Description
user	Schema.Types.ObjectId	Reference to the participating student.
q1	Schema.Types.ObjectId	Reference to the first coding challenge.
q2	Schema.Types.ObjectId	Reference to the second coding challenge.
q1Code / q2Code	String	Active source code state for question 1 and 2.
q1Language / q2Language	String	Selected compilation language.
q1Status / q2Status	String	Progress status ('not_started', 'started', 'submitted').
tabSwitchesCount	Number	Counter tracking window focus losses. Auto-submits test at 3.
status	String	Overall test session state ('active', 'completed').