# 🎓 Q-In: Smart Geo-Fenced Attendance System
**A highly secure, serverless attendance management system built with Flutter, Google Apps Script, and Biometric Authentication.**
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🚀 Overview
Q-In is a modern, anti-proxy attendance system that entirely eliminates the need for expensive servers. It leverages a student’s own smartphone hardware (Biometrics and GPS) combined with a completely free Google Sheets backend to manage classroom attendance securely and efficiently.
✨ Key Features
- 🔒 Device Locking: Accounts are permanently bound to a single physical device ID upon the first login. Students cannot log in on their friends’ phones.
- 👤 Biometric & M-PIN Security: Uses FaceID, Fingerprint, or a custom 4-digit M-PIN to secure the student dashboard.
- 📍 Geo-Fenced QR Scanning: Attendance is only accepted if the student’s GPS location is within 100 meters of the teacher’s generated QR code location.
- ⏳ Time-Sensitive Tokens: Teacher-generated QR codes contain encrypted timestamps and expire automatically after 5 minutes to prevent sharing photos of the QR code.
- 📊 Automated Subject Matrix: The Google Apps Script automatically generates clean, day-by-day attendance spreadsheets (Matrix format) for every individual subject.
- 💸 Zero Backend Costs: 100% powered by Google Apps Script and Google Sheets API.
🏗️ System Architecture
The ecosystem consists of three parts:
- Google Sheets (Database): Acts as the central hub. Admins input student rosters and subject lists here.
- Apps Script (API): The middleware that processes attendance logic, verifies GPS/Device IDs, prevents duplicates, and builds the attendance matrix.
- Flutter App (Client): The premium dark-themed mobile app used by students to claim accounts, view detailed attendance history, and scan QR codes.
- Web Portal (Teacher): A clean, glassmorphism HTML interface for teachers to generate secure, geo-tagged QR codes live in the classroom.
🛠️ Setup Instructions
Phase 1: Google Sheet Configuration
- Create a new Google Sheet.
- Create exactly three tabs named exactly as follows:
Students (Row 1 Headers: Timestamp, Name, RollNo, Class, Semester, DeviceID)Attendance (Row 1 Headers: Timestamp, Date, Subject, RollNo, Name, DeviceID)Subjects (Row 1 Headers: Class, Semester, SubjectName, SubjectCode, TotalLectures)
- Pre-fill the
Students and Subjects tabs with your university data. Leave the DeviceID column entirely blank.
Phase 2: Deploy Google Apps Script
- In your Google Sheet, click Extensions > Apps Script.
- Delete any existing code and paste the complete
code.gs file provided below.
- Click Deploy > New deployment.
- Select Type: Web app.
- Set Execute as:
Me and Who has access: Anyone.
- Click Deploy and authorize the necessary permissions.
- Copy the generated Web App URL.
📜 Click here to view the complete Apps Script Code (code.gs)
```javascript
function doPost(e) {
var lock = LockService.getScriptLock();
try { lock.waitLock(30000); } catch (err) { return createJSONOutput({ "status": "error", "message": "Server busy" }); }
try {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var studentsSheet = ss.getSheetByName("Students");
var attendanceSheet = ss.getSheetByName("Attendance");
var subjectsSheet = ss.getSheetByName("Subjects");
var params = JSON.parse(e.postData.contents);
var action = params.action;
// 1. CLAIM ACCOUNT
if (action === "claim_account") {
var reqRoll = String(params.rollNo).trim().toUpperCase();
var reqDevice = String(params.deviceId).trim();
var data = studentsSheet.getDataRange().getValues();
for (var i = 1; i < data.length; i++) {
if (String(data[i][2]).trim().toUpperCase() === reqRoll) {
var dbDevice = String(data[i][5]).trim();
if (dbDevice !== "" && dbDevice !== "null" && dbDevice !== reqDevice && reqRoll !== "GOOGLE_TEST") {
return createJSONOutput({ "status": "error", "message": "This account is already locked to another device." });
}
studentsSheet.getRange(i + 1, 6).setValue(reqDevice);
return createJSONOutput({ "status": "success", "student": { "name": data[i][1], "rollNo": data[i][2], "class": data[i][3], "sem": data[i][4] } });
}
}
return createJSONOutput({ "status": "error", "message": "Roll Number not found. Contact Admin." });
}
// 2. GET DASHBOARD DETAILS
if (action === "get_student_details") return getStudentDetails(params, studentsSheet, subjectsSheet, ss);
// 3. MARK ATTENDANCE
if (action === "mark_attendance") return markAttendance(params, studentsSheet, attendanceSheet, ss);
// 4. GET CLASSES
if (action === "get_classes") return getAvailableClasses(subjectsSheet);
return createJSONOutput({ "status": "error", "message": "Unknown Action" });
} catch (e) {
return createJSONOutput({ "status": "error", "message": "Error: " + e.toString() });
} finally {
lock.releaseLock();
}
}
function getAvailableClasses(subjectsSheet) {
if (!subjectsSheet) return createJSONOutput({"status": "error", "message": "Subjects sheet missing"});
var data = subjectsSheet.getDataRange().getValues();
var classMap = {};
for (var i = 1; i < data.length; i++) {
var cls = String(data[i][0]).trim(); var sem = String(data[i][1]).trim();
if (cls && sem) { if (!classMap[cls]) classMap[cls] = {}; classMap[cls][sem] = true; }
}
var result = {};
for (var c in classMap) { result[c] = Object.keys(classMap[c]).sort(); }
return createJSONOutput({"status": "success", "data": result});
}
function getStudentDetails(params, studentsSheet, subjectsSheet, ss) {
var deviceId = String(params.deviceId).trim();
var studentData = studentsSheet.getDataRange().getValues();
var foundStudent = null;
for (var i = 1; i < studentData.length; i++) {
if (String(studentData[i][5]).trim() == deviceId) {
foundStudent = { "name": studentData[i][1], "rollNo": studentData[i][2], "class": String(studentData[i][3]).trim(), "sem": String(studentData[i][4]).trim() };
break;
}
}
if (!foundStudent) return createJSONOutput({ "status": "error", "message": "Device not recognized. Please claim account again." });
var subjectList = [];
if (subjectsSheet) {
var subData = subjectsSheet.getDataRange().getValues();
for (var j = 1; j < subData.length; j++) {
if (String(subData[j][0]).trim() == foundStudent.class && String(subData[j][1]).trim() == foundStudent.sem) {
subjectList.push({ "name": subData[j][2], "code": String(subData[j][3]).trim(), "total": subData[j][4] || 1 });
}
}
}
var history = [];
var stats = {};
for (var s = 0; s < subjectList.length; s++) {
var subCode = subjectList[s].code;
var subSheet = ss.getSheetByName(subCode);
if (subSheet) {
var data = subSheet.getDataRange().getValues();
if (data.length > 0) {
var headers = data[0];
var studentRow = null;
for (var r = 1; r < data.length; r++) {
if (String(data[r][0]) == String(foundStudent.rollNo)) { studentRow = data[r]; break; }
}
for (var c = 4; c < headers.length; c++) {
var isPresent = studentRow ? (studentRow[c] === "P") : false;
history.push({
"lecture": headers[c] + " (" + subCode + ")",
"status": isPresent ? "Present" : "Absent"
});
if (isPresent) {
stats[subCode] = (stats[subCode] || 0) + 1;
}
}
}
}
}
history.sort(function(a, b) {
return b.lecture.localeCompare(a.lecture);
});
return createJSONOutput({ "status": "success", "student": foundStudent, "subjects": subjectList, "attendance_counts": stats, "history": history });
}
function markAttendance(params, studentsSheet, attendanceSheet, ss) {
var inputDevice = String(params.deviceId).trim();
var inputSubject = String(params.subject).trim().toUpperCase();
var inputDate = String(params.date).trim();
var studentData = studentsSheet.getDataRange().getValues();
var sName = "", sRoll = "", sClass = "", sSem = "", found = false;
for (var i = 1; i < studentData.length; i++) {
if (String(studentData[i][5]).trim() == inputDevice) {
sName = studentData[i][1];
sRoll = studentData[i][2];
sClass = studentData[i][3];
sSem = studentData[i][4];
found = true; break;
}
}
if (!found) return createJSONOutput({ "status": "error", "message": "Device not registered" });
var attData = attendanceSheet.getDataRange().getValues();
for (var j = 1; j < attData.length; j++) {
var rowDate = attData[j][1];
var sheetDateStr = (rowDate instanceof Date) ? Utilities.formatDate(rowDate, Session.getScriptTimeZone(), "yyyy-MM-dd") : String(rowDate).trim().substring(0, 10);
if (sheetDateStr == inputDate && String(attData[j][2]).trim().toUpperCase() == inputSubject && String(attData[j][5]).trim() == inputDevice) {
return createJSONOutput({ "status": "error", "message": "Already marked today!" });
}
}
attendanceSheet.appendRow([new Date(), "'" + inputDate, "'" + inputSubject, sRoll, sName, inputDevice]);
updateSubjectMatrix(ss, sRoll, sName, sClass, sSem, inputDate, inputSubject);
return createJSONOutput({ "status": "success", "message": "Attendance Marked!" });
}
function createJSONOutput(data) { return ContentService.createTextOutput(JSON.stringify(data)).setMimeType(ContentService.MimeType.JSON); }
function updateSubjectMatrix(ss, rollNo, name, sClass, sSem, date, subjectCode) {
var sheet = ss.getSheetByName(subjectCode);
if (!sheet) {
sheet = ss.insertSheet(subjectCode);
}
var data = sheet.getDataRange().getValues();
if (data.length == 0) {
sheet.appendRow(["Roll No", "Student Name", "Class", "Semester"]);
data = sheet.getDataRange().getValues();
}
var headerRow = data[0];
var colIndex = headerRow.indexOf(date);
if (colIndex == -1) {
colIndex = headerRow.length;
sheet.getRange(1, colIndex + 1).setValue(date);
}
var rowIndex = -1;
for (var i = 1; i < data.length; i++) {
if (String(data[i][0]) == String(rollNo)) { rowIndex = i; break; }
}
if (rowIndex == -1) {
sheet.appendRow([rollNo, name, sClass, sSem]);
rowIndex = sheet.getLastRow() - 1;
}
sheet.getRange(rowIndex + 1, colIndex + 1).setValue("P");
}