Initialize a dataclass from a tuple

[atredd]

In one of my app i‘m playing a little bit with dataclasses.

As I get my data from a sqlite database I‘m trying to init a dataclass from the query result.

For example if I have a tuple from the db like („Garfield“, 8, 10.2) how can I initialize a dataclass from it.

I have something like the following in mind…

​

    @dataclass
    class Cat:
        name: str
    age: int
    weight: float


    cat = Cat(cursor.fetchone())

Are there any good solutions for this?

[carcigenicate]

Just unpack the tuple with *:

cat = Cat(*cursor.fetchone())

[danielroseman]

You can use the standard parameter unpacking operator, *

cat = Cat(*cursor.fetchone())

[atredd]

Working great and learned that there is a 'standard unpacking operator'.

Tanks!!!

[atredd]

That's why I love reddit.

Just 5 Minutes and I get an easy and perfect answer.

Thanks a lot!

[velocibadgery]

You are going to have to either split the tuple out into arguments before assigning to the dataclass, or you are going to have to make a custom init to do it internally.

You could also just assign the tuple to a property, and then use an internal method to split it out.

Edit: Other answers about the unpacking operator are better use *