feat: tags for expenses, filters by tags in statistics

models/expense.py

@@ -1,7 +1,7 @@
 from datetime import datetime, date
 from typing import TYPE_CHECKING
 
-from sqlalchemy import ForeignKey
+from sqlalchemy import ForeignKey, Table, Column
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from models import BaseModel
@@ -10,6 +10,14 @@ if TYPE_CHECKING:
     from models import User
 
 
+expenses_expense_tags = Table(
+    'expenses_expense_tags',
+    BaseModel.metadata,
+    Column('expense_id', ForeignKey('expenses.id', ondelete='CASCADE'), primary_key=True),
+    Column('expense_tag_id', ForeignKey('expense_tags.id'), primary_key=True),
+)
+
+
 class Expense(BaseModel):
     __tablename__ = 'expenses'
 
@@ -22,3 +30,22 @@ class Expense(BaseModel):
 
     created_by_user_id: Mapped[int] = mapped_column(ForeignKey("users.id"), nullable=False)
     created_by_user: Mapped["User"] = relationship(foreign_keys=[created_by_user_id])
+
+    tags: Mapped[list["ExpenseTag"]] = relationship(
+        secondary=expenses_expense_tags,
+        lazy='selectin',
+        back_populates='expenses',
+        cascade='all, delete',
+    )
+
+
+class ExpenseTag(BaseModel):
+    __tablename__ = 'expense_tags'
+    id: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str] = mapped_column(unique=True)
+
+    expenses: Mapped[list["Expense"]] = relationship(
+        secondary=expenses_expense_tags,
+        lazy='selectin',
+        back_populates='tags',
+    )