ValueError: 'missing' must not be set for required fields.

[MoonlightCapital]

I have recently updated to v3.0.0 and those errors are now popping up while trying to instantiate a schema:

Traceback (most recent call last):
  File "C:\Users\Redacted\lab-assistant\lab-assistant-env\lib\site-packages\discord\client.py", line 343, in _run_event
    await coro(*args, **kwargs)
  File "C:\Users\Redacted\lab-assistant\cogs\botmonitor.py", line 45, in on_member_update
    guild_data = await self.bot.get_guild_data(guild)
  File "C:\Users\Redacted\lab-assistant\internal\botclass.py", line 62, in get_guild_data
    from database.Guild import Guild
  File "C:\Users\Redacted\lab-assistant\database\Guild.py", line 6, in <module>
    from database.Team import Team
  File "C:\Users\Redacted\lab-assistant\database\Team.py", line 7, in <module>
    class Team(Document):
  File "C:\Users\Redacted\lab-assistant\database\Team.py", line 12, in Team
    role_id = IntField(required=True, default=0)
  File "C:\Users\Redacted\lab-assistant\lab-assistant-env\lib\site-packages\umongo\abstract.py", line 133, in __init__
    super().__init__(*args, **kwargs)
  File "C:\Users\Redacted\lab-assistant\lab-assistant-env\lib\site-packages\marshmallow\fields.py", line 940, in __init__
    super().__init__(**kwargs)
  File "C:\Users\Redacted\lab-assistant\lab-assistant-env\lib\site-packages\marshmallow\fields.py", line 889, in __init__
    super().__init__(**kwargs)
  File "C:\Users\Redacted\lab-assistant\lab-assistant-env\lib\site-packages\marshmallow\fields.py", line 188, in __init__
    raise ValueError("'missing' must not be set for required fields.")
ValueError: 'missing' must not be set for required fields.

However, I am never setting 'missing' anywhere. Here's a document registration example:

from umongo import Document, validate
from umongo.fields import *

from internal.database_init import instance

@instance.register
class Team(Document):
    """A team table"""

    guild = IntField(required=True)
    name = StrField(required=True, validate=validate.Length(min=1, max=32))
    role_id = IntField(required=True, default=0)
    description = StringField(required=True, validate=validate.Length(min=1, max=1000))
    joinable = BoolField(required=True, default=False)
    leader_id = IntField(required=True, default=0)
    member_perms = ListField(StrField, required=True, default=[])

    codes = ListField(StrField, required=True, default=[])

Could anyone tell me why this is happening? I use defaults to not create duplicated code on my insertions.

[lafrech]

default in umongo translates to missing in marshmallow.

missing + required is forbidden in marshmallow.

Admittedly, the error message is not that helpful. Perhaps we could catch that earlier.

What's the point of having a default on a required field?

[MoonlightCapital]

What's the point of having a default on a required field?

It's so when I create a document I need to initialize some defaults that are always the same and also required for the doc to work without many checks, and since I have multiple sources of insertions, it's better to have those static values set in there. If there's another recommended way to do this, I'm all ears.

[lafrech]

I don't get it.

• required means that if the value is missing, an exception is raised.
• default is the value used if the value is missing

You can't have both. If you set a default, the value may be missing in the input, it will be replaced by the default value. No need to set required.