Automatic conversion from float to int?

Bug

For bugs/questions:

• OS: Any
• Python version import sys; print(sys.version): 3.7
• Pydantic version import pydantic; print(pydantic.VERSION): 0.18.1

You got a misfeature there, buddy. Automatic conversion (by default!) from float to int is a terrible idea:

from pydantic import PositiveInt, BaseModel

class MySchema(BaseModel): 
    int_only: PositiveInt

MySchema(int_only=3.1415)
# <MySchema int_only=3>

I am working with 2 separate codebases that communicate with each other. One of these apps could have the wrong idea about the type of a variable, it would be great if the validation framework caught this. I wanted to use Pydantic to validate the data. How can I circumvent this misfeature? (Please add the answer to the documentation.)

[samuelcolvin]

You got a misfeature there, buddy. Automatic conversion (by default!) from float to int is a terrible idea

Wow, what a great way of not getting help.

I try really hard to understand peoples problems and always give constructive answers, but here I’m really tempted to just click close.

Do you always start conversations with volunteers where you would like help by calling them “buddy”, then telling them they have "terrible idea"s? Great idea buddy.

This is by considered design, but you can change the behaviour using validators with pre=True.

Or you can use another library. Not a problem with me.

[nandoflorestan]

Dear Samuel,

I apologize. You are absolutely right that I was arrogant. It’s nothing personal. I repeat this mistake nearly every week and then I resolve to watch it and then suddenly it happens again. I seem unable to shake it, but I must not give up. I am not being sarcastic, I have struggled with this all my life. Therapy had no power to shadow my dad’s example. If it means anything, no offense was intended, but I spoke as if I already knew you, trying to be a little funny, and that’s the way it always happens.

Again, I am sorry and I hope you can forgive me. I did not really mean to talk down to you, although it totally appears that way. I truly admire your work in this library (one that I couldn’t have written), I think it is awesome, and this is why I am going to insist.

I still think that the default should be changed – we should not build a validation library that declines to validate types by default. (Python is a strongly typed, if dynamically typed, language.) In the case I brought to you, 3.14 is being converted to 3 by default, which is information loss, happening exactly when we wanted to prevent information loss.

At a minimum, a configuration option should be added to control this behavior.

I guess that’s the best case I can make for it.

Best regards, Nando.