asdict and astuple

Learn conversion with dataclasses.asdict and astuple.

asdict and astuple

The asdict and astuple functions in the dataclasses module convert a dataclass instance to a dict and a tuple respectively. This is useful for passing data in another form.

Example: asdict(p) returns {'x': 3, 'y': 4}; astuple(p) returns (3, 4). Both are imported from the dataclasses module. These conversions are common when exporting data to a dict-expecting API or a database.

Which format for what?

asdict fits when you export data to a dict-expecting API; the keys are the field names. astuple fits when you need ordered access or pass data by position to a function.

Example: you can save a Point instance with save_dict(asdict(p)) and unpack it to a distance function with distance(*astuple(p)). Neither conversion changes the original instance; a new object is returned.

Exercise Convert Point to dict and tuple

Start with from dataclasses import dataclass, asdict, astuple. Define a Point class with @dataclass; include fields x: int = 0 and y: int = 0. Then create an instance with p = Point(3, 4) and call print(asdict(p)) and print(astuple(p)).

Show example solution

# Convert the Point instance with asdict and astuple
from dataclasses import dataclass, asdict, astuple

@dataclass
class Point:
    x: int = 0
    y: int = 0

p = Point(3, 4)
print(asdict(p))
print(astuple(p))

Test yourself

What does asdict(p) return?
- A list
- A tuple
- A dict
- A set
Show answer

A dict — asdict converts the instance to a dict.

Complete the import line

from dataclasses import dataclass, ____

@dataclass
class Point:
    x: int = 0
    y: int = 0

Show answer

from dataclasses import dataclass, asdict, astuple

@dataclass
class Point:
    x: int = 0
    y: int = 0

Match the conversion functions

asdict

Converts to dict
astuple

Converts to tuple
{'x': 3, 'y': 4}

Dict result
(3, 4)

Tuple result

Next lesson: Summary - Dataclasses

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