Add fields from APIFlask?

[sloria]

apiflask has File and Config fields, which may be appropriate to have in flask-marshmallow: https://github.com/apiflask/apiflask/blob/main/src/apiflask/fields.py

as well as validators to use with File fields: https://github.com/apiflask/apiflask/blob/main/src/apiflask/validators.py

[sloria]

cc @greyli , you may be interested in this :)

[greyli]

Sure, I could help migrate them here. I thought about it, but it was lost on my to-do list.

I will submit a pull request to add the Config field.

@uncle-lv Could you help migrate the File related field and validators to flask-marshmallow?

[uncle-lv]

Sure, I could help migrate them here. I thought about it, but it was lost on my to-do list.

I will submit a pull request to add the Config field.

@uncle-lv Could you help migrate the File related field and validators to flask-marshmallow?

Of course.

[sirosen]

I haven't done very much here since I first got involved on this project, but I'd be happy to help with these too!

Config seems pretty small and easy to grasp. I'll need to read up a bit on apiflask's current File tooling.

[greyli]

Created the pull request for the Config field: #281

[sirosen]

Wow, these got done in a flash! I think this is good to close, but please reopen if I'm wrong.

I noticed that Config uses _CHECK_ATTRIBUTE, which feels a little like an implementation detail in marshmallow leaking into downstream libraries. Would it be better for the field to define serialize instead of _serialize? (I haven't thought about this very hard, so apologies if that is just wrong-headed. 😄 )

[sloria]

_CHECK_ATTRIBUTE isn't just an implementation detail--it's meant to be set by subclasses of Field when the attribute isn't meant to be accessed on the object to be serialized: https://github.com/marshmallow-code/marshmallow/blob/e099e058f8d17af08369d4485622d1c14f9084ed/src/marshmallow/fields.py#L138-L141

Config is very similar to fields.Constant, which sets _CHECK_ATTRIBUTE to False.

[sloria]

These changes are released in 1.0.0