updated code

app/models.py

@@ -4,6 +4,10 @@ from datetime import datetime
 
 String_size = db.String(255)
 
+
+# ==========================
+# USER MODEL
+# ==========================
 class User(UserMixin, db.Model):
     id = db.Column(db.Integer, primary_key=True)
     username = db.Column(String_size, unique=True, nullable=False)
@@ -22,37 +26,15 @@ class User(UserMixin, db.Model):
     def __repr__(self):
         return f'<User {self.username}>'
 
-# ==========================
-# DB models below
-# ==========================
-
-class Task(db.Model):
-    id = db.Column(db.Integer, primary_key=True)
-    district = db.Column(String_size)
-    block_name = db.Column(String_size)
-    village_name = db.Column(String_size)
-    serial_number = db.Column(String_size)
-    parent_id = db.Column(String_size, nullable=True)
-    parent_task_name = db.Column(db.Text)
-    task_name = db.Column(db.Text)
-    unit = db.Column(String_size)
-    qty = db.Column(String_size)
-    rate = db.Column(String_size)
-    boq_amount = db.Column(String_size)
-    previous_billed_qty = db.Column(String_size)
-    previous_billing_amount = db.Column(String_size)
-    remaining_amount = db.Column(String_size) 
-    in_this_ra_bill_qty = db.Column(String_size)
-    in_this_ra_billing_amount = db.Column(String_size)
-    cumulative_billed_qty = db.Column(String_size)
-    cumulative_billed_amount = db.Column(String_size)
-    variation_qty = db.Column(String_size)
-    variation_amount = db.Column(String_size)
-    remark = db.Column(String_size, nullable=True)
-    uploaded_at = db.Column(db.DateTime, default=datetime.utcnow)
 
+# ==========================
+# WORK DETAIL (PARENT)
+# ==========================
 class WorkDetail(db.Model):
+    __tablename__ = 'work_detail'
+
     id = db.Column(db.Integer, primary_key=True)
+
     name_of_work = db.Column(String_size)
     cover_agreement_no = db.Column(String_size)
     name_of_contractor = db.Column(String_size)
@@ -63,12 +45,74 @@ class WorkDetail(db.Model):
     scheme_id = db.Column(String_size)
     measurement_book = db.Column(String_size)
     date_of_billing = db.Column(String_size)
-    uploaded_at = db.Column(db.DateTime, default=datetime.utcnow)
-    district = db.Column(db.String(255))
+    district = db.Column(String_size)
+
+    uploaded_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    # 🔥 RELATIONSHIP (VERY IMPORTANT)
+    tasks = db.relationship(
+        'Task',
+        backref='work_detail',
+        cascade="all, delete-orphan"
+    )
+
+
+# ==========================
+# TASK (CHILD TABLE)
+# ==========================
+class Task(db.Model):
+    __tablename__ = 'task'
 
-class ActivityLog(db.Model):  # OUTSIDE WorkDetail
     id = db.Column(db.Integer, primary_key=True)
-    user = db.Column(db.String(100))  # can link with User model later
+
+    # 🔥 ADD THIS (FIX YOUR ERROR)
+    work_detail_id = db.Column(db.Integer, db.ForeignKey('work_detail.id'))
+
+    district = db.Column(String_size)
+    block_name = db.Column(String_size)
+    village_name = db.Column(String_size)
+
+    serial_number = db.Column(String_size)
+
+    parent_id = db.Column(String_size, nullable=True)
+    parent_task_name = db.Column(db.Text)
+
+    task_name = db.Column(db.Text)
+
+    unit = db.Column(String_size)
+
+    # 👉 keep as string (your current structure)
+    qty = db.Column(String_size)
+    rate = db.Column(String_size)
+    boq_amount = db.Column(String_size)
+
+    previous_billed_qty = db.Column(String_size)
+    previous_billing_amount = db.Column(String_size)
+    remaining_amount = db.Column(String_size)
+
+    in_this_ra_bill_qty = db.Column(String_size)
+    in_this_ra_billing_amount = db.Column(String_size)
+
+    cumulative_billed_qty = db.Column(String_size)
+    cumulative_billed_amount = db.Column(String_size)
+
+    variation_qty = db.Column(String_size)
+    variation_amount = db.Column(String_size)
+
+    remark = db.Column(String_size, nullable=True)
+
+    uploaded_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    # 🔥 OPTIONAL BUT VERY USEFUL
+    row_index = db.Column(db.Integer)
+
+
+# ==========================
+# ACTIVITY LOG
+# ==========================
+class ActivityLog(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    user = db.Column(db.String(100))
     action = db.Column(db.String(255))
     details = db.Column(db.Text)
-    timestamp = db.Column(db.DateTime, default=datetime.utcnow)
+    timestamp = db.Column(db.DateTime, default=datetime.utcnow)