refactor: fastapi dependency injections and consistent route naming

backend/todo/crud/todos.py

@@ -8,7 +8,8 @@ from todo.models import todos as todomodel
 from todo.models import users as usermodel
 from todo.schemas import todos as todoschema
 from todo.utils.exceptions import NotFoundException, InvalidFilterParameterException
-from todo.models.common import SortOrder
+from todo.dependencies.common import SortOrder
+from todo.dependencies.todos import SortableTodoItemField
 
 
 def create_todo(db: Session, todo: todoschema.TodoItemCreate, user_id: int) -> todoschema.TodoItem:
@@ -44,7 +45,7 @@ def read_todos_for_user(
         db: Session,
         user_id: int,
         skip: int = 0, limit: int = 100,
-        sortby: todomodel.SortableTodoItemField = todomodel.SortableTodoItemField('updated'),
+        sortby: SortableTodoItemField = SortableTodoItemField('updated'),
         sortorder: SortOrder = SortOrder['desc'],
     ) -> list[todoschema.TodoItem]:
     """Returns a range of todo-items of the user with the specified user_id from the database."""

backend/todo/crud/users.py

@@ -6,7 +6,8 @@ from sqlalchemy.orm import Session
 
 from todo.models import users as usermodel
 from todo.schemas import users as userschema
-from todo.models.common import SortOrder
+from todo.dependencies.common import SortOrder
+from todo.dependencies.users import SortableUserField
 from todo.utils.exceptions import NotFoundException, InvalidFilterParameterException
 
 
@@ -60,7 +61,7 @@ def read_user_by_email(db: Session, email: str) -> userschema.User:
 def read_users(
         db: Session,
         skip: int = 0, limit: int = 100,
-        sortby: usermodel.SortableUserField = usermodel.SortableUserField('id'),
+        sortby: SortableUserField = SortableUserField('id'),
         sortorder: SortOrder = SortOrder['asc'],
     ) -> list[userschema.User]:
     """Returns an range of users from the database."""

backend/todo/dependencies/common.py

@@ -0,0 +1,43 @@
+"""This module provides FastAPI dependencies for commonly used query parameters."""
+
+
+from enum import Enum
+from typing import Callable
+
+import sqlalchemy
+
+from todo.database.engine import Base
+
+
+class SortOrder(Enum):
+    """Possible sort orders for database queries."""
+
+    asc = 'asc'
+    desc = 'desc'
+
+    @property
+    def call(self) -> Callable:
+        """Returns the sqlalchemy sort function depending on the instance value."""
+
+        if self.value == 'asc':
+            return sqlalchemy.asc
+        elif self.value == 'desc':
+            return sqlalchemy.desc
+        else:
+            raise RuntimeError("Logic error.")
+
+
+class PaginationParams():
+    """Represents query parameters used for pagination, when querying for a list of items.
+
+    Attributes
+    ----------
+    skip : int
+        The number of items to be skipped from the start of the start of the list.
+    limit : int
+        Limits the total number of returned list items to the specified number.
+    """
+
+    def __init__(self, skip: int = 0, limit: int = 100):
+        self.skip = skip
+        self.limit = limit

backend/todo/dependencies/todos.py

@@ -0,0 +1,35 @@
+"""Query parameters used to sort todo-items."""
+
+from enum import Enum
+
+from sqlalchemy import Column
+
+from todo.models.todos import TodoItem
+from todo.dependencies.common import PaginationParams, SortOrder
+
+
+class SortableTodoItemField(Enum):
+    """Defines which fields todo-item lists can be sorted on."""
+
+    id = 'id'
+    title = 'title'
+    done = 'done'
+    created = 'created'
+    updated = 'updated'
+    finished = 'finished'
+
+    @property
+    def field(self) -> Column:
+        return getattr(TodoItem, self.value)
+
+
+class TodoItemSortablePaginationParams(PaginationParams):
+    def __init__(
+            self,
+            skip: int = 0, limit: int = 100,
+            sortby: SortableTodoItemField = SortableTodoItemField['updated'],
+            sortorder: SortOrder = SortOrder['desc'],
+        ):
+        super().__init__(skip=skip, limit=limit)
+        self.sortby = sortby
+        self.sortorder = sortorder

backend/todo/dependencies/users.py

@@ -0,0 +1,35 @@
+"""Query parameters used to sort users."""
+
+from enum import Enum
+
+from sqlalchemy import Column
+
+from todo.models.users import User
+from todo.dependencies.common import PaginationParams, SortOrder
+
+
+class SortableUserField(Enum):
+    """Defines which fields user lists can be sorted on."""
+
+    id = 'id'
+    email = 'email'
+    created = 'created'
+    updated = 'updated'
+    first_name = 'first_name'
+    last_name = 'last_name'
+
+    @property
+    def field(self) -> Column:
+        return getattr(User, self.value)
+
+
+class UserSortablePaginationParams(PaginationParams):
+    def __init__(
+            self,
+            skip: int = 0, limit: int = 100,
+            sortby: SortableUserField = SortableUserField['id'],
+            sortorder: SortOrder = SortOrder['asc'],
+        ):
+        super().__init__(skip=skip, limit=limit)
+        self.sortby = sortby
+        self.sortorder = sortorder

backend/todo/models/common.py

@@ -1,26 +0,0 @@
-"""This module contains common utilities for handling models."""
-
-import enum
-from typing import Callable
-
-import sqlalchemy
-
-
-class SortOrder(enum.Enum):
-    """Possible sort orders for database queries."""
-
-    asc = 'asc'
-    ASC = 'asc'
-    desc = 'desc'
-    DESC = 'desc'
-
-    @property
-    def call(self) -> Callable:
-        """Returns the sqlalchemy sort function depending on the instance value."""
-
-        if self.value == 'asc':
-            return sqlalchemy.asc
-        elif self.value == 'desc':
-            return sqlalchemy.desc
-        else:
-            raise RuntimeError("Logic error.")

backend/todo/models/todos.py

@@ -1,8 +1,6 @@
 """This module defines the SQL data model for todo items."""
 
-import enum
-
-from sqlalchemy import Column, ForeignKey, Integer, String, DateTime, Date, Enum, CheckConstraint, Boolean
+from sqlalchemy import Column, ForeignKey, Integer, String, DateTime, Boolean
 from sqlalchemy.sql.functions import now
 from sqlalchemy.orm import relationship
 
@@ -26,18 +24,3 @@ class TodoItem(Base):
 
     user_id = Column('user_id', Integer, ForeignKey('users.id', ondelete="CASCADE"), nullable=False, index=True)
     user = relationship(User, back_populates="todo_items", uselist=False)
-
-
-class SortableTodoItemField(enum.Enum):
-    """Defines which fields todo-item lists can be sorted on."""
-
-    id = 'id'
-    title = 'title'
-    done = 'done'
-    created = 'created'
-    updated = 'updated'
-    finished = 'finished'
-
-    @property
-    def field(self) -> Column:
-        return getattr(TodoItem, self.value)

backend/todo/models/users.py

@@ -1,7 +1,5 @@
 """This module defines the SQL data model for users."""
 
-import enum
-
 from sqlalchemy import Column, Integer, String, DateTime
 from sqlalchemy.sql.functions import now
 from sqlalchemy.orm import relationship
@@ -23,18 +21,3 @@ class User(Base):
     last_name = Column('last_name', String, nullable=False, index=True)
 
     todo_items = relationship("TodoItem", back_populates="user", uselist=True, cascade="all, delete")
-
-
-class SortableUserField(enum.Enum):
-    """Defines which fields user lists can be sorted on."""
-
-    id = 'id'
-    email = 'email'
-    created = 'created'
-    updated = 'updated'
-    first_name = 'first_name'
-    last_name = 'last_name'
-
-    @property
-    def field(self) -> Column:
-        return getattr(User, self.value)

backend/todo/routes/todos.py

@@ -1,5 +1,7 @@
 """This module contains endpoints for operations related to users."""
 
+from typing import Annotated
+
 from fastapi import APIRouter, Depends, HTTPException
 from sqlalchemy.orm import Session
 
@@ -8,12 +10,11 @@ from todo.schemas import todos as todoschema
 from todo.crud import todos as todocrud
 from todo.utils.exceptions import NotFoundException, InvalidFilterParameterException
 from todo.utils.exceptions import create_exception_dict as fmt
-from todo.models.todos import SortableTodoItemField
-from todo.models.common import SortOrder
+from todo.dependencies.todos import TodoItemSortablePaginationParams
 
 
 router = APIRouter(
-    prefix="/todo",
+    prefix="/todos",
     tags=["todo-items"]
 )
 
@@ -42,13 +43,16 @@ def read_todo(todo_id: int, db: Session = Depends(get_db)):
 @router.get("/user/{user_id}", response_model=list[todoschema.TodoItem])
 def read_todos(
         user_id: int,
-        skip: int = 0, limit: int = 100,
-        sortby: SortableTodoItemField = SortableTodoItemField['updated'],
-        sortorder: SortOrder = SortOrder['desc'],
+        commons: Annotated[TodoItemSortablePaginationParams, Depends(TodoItemSortablePaginationParams)],
         db: Session = Depends(get_db)
     ):
     try:
-        return todocrud.read_todos_for_user(db=db, user_id=user_id, skip=skip, limit=limit, sortby=sortby, sortorder=sortorder)
+        return todocrud.read_todos_for_user(
+            db=db,
+            user_id=user_id,
+            skip=commons.skip, limit=commons.limit,
+            sortby=commons.sortby, sortorder=commons.sortorder,
+        )
     except InvalidFilterParameterException as e:
         raise HTTPException(400, fmt(str(e)))
     except NotFoundException as e:

backend/todo/routes/users.py

@@ -1,5 +1,7 @@
 """This module contains endpoints for operations related to users."""
 
+from typing import Annotated
+
 from fastapi import APIRouter, Depends, HTTPException
 from sqlalchemy.orm import Session
 
@@ -8,8 +10,7 @@ from todo.schemas import users as userschema
 from todo.crud import users as usercrud
 from todo.utils.exceptions import NotFoundException, InvalidFilterParameterException
 from todo.utils.exceptions import create_exception_dict as fmt
-from todo.models.common import SortOrder
-from todo.models.users import SortableUserField
+from todo.dependencies.users import UserSortablePaginationParams
 
 
 router = APIRouter(
@@ -43,13 +44,17 @@ def read_user(id: int, db: Session = Depends(get_db)):
 
 @router.get("/", response_model=list[userschema.User])
 def read_users(
-        skip: int = 0, limit: int = 100,
-        sortby: SortableUserField = SortableUserField['id'],
-        sortorder: SortOrder = SortOrder['asc'],
+        commons: Annotated[UserSortablePaginationParams, Depends(UserSortablePaginationParams)],
         db: Session = Depends(get_db)
     ):
     try:
-        return usercrud.read_users(db=db, skip=skip, limit=limit, sortby=sortby, sortorder=sortorder)
+        return usercrud.read_users(
+            db=db,
+            skip=commons.skip,
+            limit=commons.limit,
+            sortby=commons.sortby,
+            sortorder=commons.sortorder
+        )
     except InvalidFilterParameterException as e:
         raise HTTPException(400, fmt(str(e)))
 

backend/todo/schemas/common.py

@@ -0,0 +1,12 @@
+"""This module contains common functions for schema validation."""
+
+def is_valid_id(id: int) -> bool:
+    """Checks whether the specified id is a valid ID.
+
+    Performs a shallow check on whether the ID is a valid primary key.
+    """
+
+    if not isinstance(id, int):
+        raise TypeError(f"Expected an integer but got: {type(id)}")
+
+    return id > 0

backend/todo/schemas/todos.py

@@ -6,6 +6,8 @@ from typing import Optional
 
 from pydantic import BaseModel, validator
 
+from todo.schemas.common import is_valid_id
+
 
 class AbstractTodoItemValidator(BaseModel, ABC):
     """Base class for todo-item validators shared with child classes."""
@@ -55,5 +57,11 @@ class TodoItem(AbstractTodoItem):
     updated: datetime
     finished: datetime | None
 
+    @validator('id')
+    def assert_id_is_valid(cls, id):
+        if not is_valid_id(id):
+            raise ValueError("ID is invalid.")
+        return id
+
     class Config:
         orm_mode = True

backend/todo/schemas/users.py

@@ -7,6 +7,8 @@ from re import compile
 
 from pydantic import BaseModel, validator
 
+from todo.schemas.common import is_valid_id
+
 
 def is_valid_email_format(input_str: str) -> bool:
     """Checks whether the input string is a valid email address format.
@@ -106,5 +108,11 @@ class User(AbstractUser):
     created: datetime
     updated: datetime
 
+    @validator('id')
+    def assert_id_is_valid(cls, id):
+        if not is_valid_id(id):
+            raise ValueError("ID is invalid.")
+        return id
+
     class Config:
         orm_mode = True

frontend/src/routes/users/[user]/todos/+page.svelte

@@ -44,8 +44,8 @@
   const table = {
     caption: `List of TODOs for user ${data.user.first_name} ${data.user.last_name}`,
     columns: cols,
-    itemsEndpoint: `/api/todo/user/${data.user.id}/`,
-    itemCountEndpoint: `/api/todo/user/${data.user.id}/total/`,
+    itemsEndpoint: `/api/todos/user/${data.user.id}/`,
+    itemCountEndpoint: `/api/todos/user/${data.user.id}/total/`,
   };
 </script>