How do you do deep input data validation?

[Amirouche Boubekki]

It seems that aiohttp recommends using one of trafaret, colander or
jsonschema
<http://aiohttp.readthedocs.io/en/stable/tutorial.html?highlight=colander>.
I am not very familiar with those libraries.

I am wondering what's the rational behind this choice. Why is trafaret the
first in this list? Is it a strong recommendation to use trafaret?

I tried to ask a question on SO about deep validation
<https://stackoverflow.com/questions/45252612/how-do-you-validate-application-logic-using-pyramids-colander>.
Basically, how do you validate data in your project? What are the best
pratices?

TIA!