Add x-nullable support for body validators

[dmksnnk]

Closes #439

Add x-nullable support in properties by adding property validator to default Draft4Validator. It skips null-property with "x-nullable": true and then adds it back.

[coveralls]

Coverage remained the same at 100.0% when pulling d248434 on dmksnnk:nullable-in-definitions into 79e0e3d on zalando:master.

[dtkav]

It looks like this is breaking the build by not throwing the right exception when the function is given an integer as input.
See the travis build for the failure.

[dtkav]

This looks really close - there are some minor changes needed to fix the build, plus a rebase on master. Thanks for putting this together!

[dtkav]

Unfortunately this breaks the isort step in the build. See the end of the python 3.6 travis run for details.

[dmksnnk]

Can you please check for Pypy build? It can't download Pypy binaries. Otherwise all other builds are passed.

[dtkav]

hey @dmksnnk , sorry this fell off my radar. I kicked the build - seems like the problem was with travis-ci.
You code looks great to me, and I'd love to use this in the dev-2.0 branch for nullable support in openapi 3 validation.

[dtkav]

Looks great.
Did you consider pulling this into a "connexion/validators.py" file?

[dmksnnk]

@dtkav thank you for checking this. What should be my next step? Move it to connexion/validators.py? Or you are just going to use it in next 2.0 branch?

[dtkav]

Only zalando employees can merge PRs into master, so we'll have to wait for either @jmcs or @hjacobs to have a look.

I've merged it into dev-2.0 for my own purposes, but I think it would make sense to merge it into master too (so it can get out sooner). I can sort out any rebase/merge conflicts that may come up on the dev-2.0 branch.

Moving the code into another file is totally optional, I just wanted to raise the idea. I don't have a strong preference.

[dtkav]

actually, @dmksnnk if you can rebase on master, that would help.

[dtkav]

Hey @jmcs - This is looking good from my perspective. I recommend we merge this into master, what do you think?

[jmcs]

👍

[kinokrt]

Isn't this a bug ? Why x-nullable does not work on $ref ? For example:

changes:
      type: object
      properties:
        Bla:
          $ref: "#/definitions/Muhehe"
          x-nullable: true
      additionalProperties:
        $ref: "#/definitions/Muhehe"
        x-nullable: true

[dmksnnk]

@jankontrik you need to set x-nullable: true inside referenced object:

Muhehe:
    title: Muhehe
    type: object
    x-nullable: true

[kinokrt]

@dmksnnk Indeed I had that this way (x-nullable: true inside referenced object) but always ends with:
validation error: None is not of type 'object'
So that's why I've tried to define x-nullable alongside $ref.

[kinokrt]

I'm using python 3.6, connexion==1.5.2.

[dmksnnk]

if you check releases, this feature was added for version 1.5.3

[kinokrt]

@dmksnnk Yep. Sorry I know about which release. Of course I tried that on 1.5.3 but with the result above :(. Then I returned to 1.5.2 and forgot about the right version.

[dmksnnk]

I'm investigating this, but have you considered using {} for empty object instead of None/null?
I'm not sure if it is a good idea to set object to None.
Summoning help @dtkav, @jmcs

[kinokrt]

Of course it is not good I absolutely agree. But this is some legacy stuff, no way to change.

[kinokrt]

BTW the problem is always on additionalProperties when there is a x-nullable ref and None comes.