Reject blank task titles

app/schemas/task.py

@@ -1,14 +1,33 @@
 from datetime import datetime
 from typing import Optional
 
-from pydantic import BaseModel
+from pydantic import BaseModel, field_validator
+
+
+def _clean_optional_text(value: Optional[str]) -> Optional[str]:
+    if value is None:
+        return None
+    return " ".join(value.split())
 
 
 class TaskBase(BaseModel):
     title: str
     description: Optional[str] = None
     completed: bool = False
 
+    @field_validator("title")
+    @classmethod
+    def title_must_not_be_blank(cls, value: str) -> str:
+        title = " ".join(value.split())
+        if not title:
+            raise ValueError("Title cannot be blank")
+        return title
+
+    @field_validator("description")
+    @classmethod
+    def normalize_description(cls, value: Optional[str]) -> Optional[str]:
+        return _clean_optional_text(value)
+
 
 class TaskCreate(TaskBase):
     pass
@@ -19,11 +38,24 @@ class TaskUpdate(BaseModel):
     description: Optional[str] = None
     completed: Optional[bool] = None
 
+    @field_validator("title")
+    @classmethod
+    def title_must_not_be_blank(cls, value: Optional[str]) -> Optional[str]:
+        title = _clean_optional_text(value)
+        if title == "":
+            raise ValueError("Title cannot be blank")
+        return title
+
+    @field_validator("description")
+    @classmethod
+    def normalize_description(cls, value: Optional[str]) -> Optional[str]:
+        return _clean_optional_text(value)
+
 
 class TaskResponse(TaskBase):
     id: int
     created_at: datetime
     updated_at: datetime
 
     class Config:
-        from_attributes = True
+        from_attributes = True

tests/test_tasks.py

@@ -17,6 +17,12 @@ def test_create_task(client):
     assert "id" in data
 
 
+def test_create_task_rejects_blank_title(client):
+    response = client.post("/tasks/", json={"title": "   "})
+
+    assert response.status_code == 422
+
+
 def test_get_tasks(client):
     client.post("/tasks/", json={"title": "Task 1"})
     client.post("/tasks/", json={"title": "Task 2"})
@@ -47,10 +53,18 @@ def test_update_task(client):
     assert response.json()["completed"] == True
 
 
+def test_update_task_rejects_blank_title(client):
+    created = client.post("/tasks/", json={"title": "Old title"})
+    task_id = created.json()["id"]
+    response = client.put(f"/tasks/{task_id}", json={"title": "   "})
+
+    assert response.status_code == 422
+
+
 def test_delete_task(client):
     created = client.post("/tasks/", json={"title": "To delete"})
     task_id = created.json()["id"]
     response = client.delete(f"/tasks/{task_id}")
     assert response.status_code == 204
     response = client.get(f"/tasks/{task_id}")
-    assert response.status_code == 404
+    assert response.status_code == 404