UNSET

UNSET is a sentinel value that can be used to represent an unset value in a field or argument. Similar to undefined in JavaScript, this value can be used to differentiate between a field that was not set and a field that was set to None or null .

Basic Usage

import strawberry


@strawberry.input
class UpdateUserInput:
    name: str | None = strawberry.UNSET
    phone: str | None = strawberry.UNSET


@strawberry.type
class Mutation:
    @strawberry.mutation
    def update_user(self, input: UpdateUserInput) -> User:
        if input.name is not strawberry.UNSET:
            user.name = input.name
        if input.phone is not strawberry.UNSET:
            user.phone = input.phone
        return user  

Checking for UNSET

Use identity comparison to check if a value is unset:

# Correct way to check
if value is strawberry.UNSET:
    print("Value was not provided")

# Also correct
if value is not strawberry.UNSET:
    print(f"Value was provided: {value}")  

Limitations

UNSET has some limitations compared to Maybe :

1. Type Safety: UNSET doesn’t work well with type checkers since it’s typed as Any
2. Ambiguous Null Handling: With field: str | None = UNSET , it’s not immediately clear whether None means “set to null” or “not provided”
3. No Wrapper Type: Values are accessed directly, making it more difficult to distinguish the source of a None value

Migrating to Maybe

We recommend migrating to Maybe for new code. See the migration guide for details.

Quick Comparison

Related

• Maybe - The recommended alternative for input field handling
• Input Types - Defining input types