Best practice for do validation when creating/updating object?

as title.

use cloud function:
Parse.Cloud.define(
or
Parse.Cloud.beforeSave(
or
else

Both approach work, but I personally prefer to user triggers.

Thanks very much

For example, user age should be in range, there should be some validation, eg >15, what I need? listeners? rules? triggers? some programming logics? in where?

And I think the root problem is that, switch to low code platform from traditional programmer experience, I had many similar problems, but find it hard to find document/tutorial/sample
Even the commerical back4app website has only beginner level tutorials/docs

What should I start to learn?

Thanks

The documentation discusses what you need:

In particular, the More Advanced Validation section.

thanks,

so the work needed between “mbaas” and “traditional backend api programming”, has no big differences?

(edited)
i predict or guess that can save 20+% development time