Nested excludes get overwritten

It seems whenever an parent level exclude is specified with dot notation, the child field level excludes are overwritten. It would be great if they could be concatenated.

Here’s an example:

from marshmallow import fields, Schema

class FooChildSchema(Schema):
    boo = fields.String()
    far = fields.String()
    faz = fields.String()

class FooSchema(Schema):
    foo = fields.String()
    bar = fields.String()
    baz = fields.String()
    child = fields.Nested(FooChildSchema, exclude=('boo',))

obj = {
    'foo': 'foo',
    'bar': 'bar',
    'baz': 'baz',
    'child': {
        'boo': 'boo',
        'far': 'far',
        'faz': 'faz',
    },
}

serialized = FooSchema(exclude=('foo', 'child.faz')).dump(obj).data
print(serialized)

I expect :

{'child': {'far': 'far'}, 'baz': 'baz', 'bar': 'bar'}

instead, I get:

{'child': {'far': 'far', 'boo': 'boo'}, 'baz': 'baz', 'bar': 'bar'}

[deckar01]

I will pick this back up now that #772 is fixed. Thanks @lafrech.

[timc13]

@deckar01 don’t mean to be annoying - but hopefully you havent forgotten about this? 😃