What is TypedDict and when to use it?

Question

Accepted Answer

**TypedDict** defines **dictionary schemas** with type hints.

```python
from typing import TypedDict, Required, NotRequired

class UserDict(TypedDict):
    name: str
    email: str
    age: int
    bio: NotRequired[str]  # Optional key

class ProductDict(TypedDict, total=False):
    name: Required[str]  # Required key
    price: float
    description: str

# Usage
user: UserDict = {
    "name": "Alice",
    "email": "alice@example.com",
    "age": 25
}

# With defaults
from typing import TypeGuard

def is_user_dict(data: dict) -> TypeGuard[UserDict]:
    return (
        "name" in data and
        "email" in data and
        "age" in data
    )

def process(data: dict):
    if is_user_dict(data):
        print(data["name"])  # Type-safe access

# Inheriting
class ExtendedUser(UserDict):
    role: str
    is_active: bool
```

**Use cases:**
- JSON API responses.
- Configuration files.
- Database row representations.
- Replacing untyped dicts.

Python: What is TypedDict and when to use it?