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from dataclasses import dataclass
import pytest
from apischema import Undefined, ValidationError, alias, deserialize, schema, serialize
from apischema.tagged_unions import Tagged, TaggedUnion, get_tagged
@dataclass
class Bar:
field: str
class Foo(TaggedUnion):
bar: Tagged[Bar]
# Tagged can have metadata like a dataclass fields
i: Tagged[int] = Tagged(alias("baz") | schema(min=0))
# Instantiate using class fields
tagged_bar = Foo.bar(Bar("value"))
# you can also use default constructor, but it's not typed-checked
assert tagged_bar == Foo(bar=Bar("value"))
# All fields that are not tagged are Undefined
assert tagged_bar.bar is not Undefined and tagged_bar.i is Undefined
# get_tagged allows to retrieve the tag and it's value
# (but the value is not typed-checked)
assert get_tagged(tagged_bar) == ("bar", Bar("value"))
# (De)serialization works as expected
assert deserialize(Foo, {"bar": {"field": "value"}}) == tagged_bar
assert serialize(Foo, tagged_bar) == {"bar": {"field": "value"}}
with pytest.raises(ValidationError) as err:
deserialize(Foo, {"unknown": 42})
assert err.value.errors == [{"loc": ["unknown"], "err": "unexpected property"}]
with pytest.raises(ValidationError) as err:
deserialize(Foo, {"bar": {"field": "value"}, "baz": 0})
assert err.value.errors == [
{"loc": [], "err": "property count greater than 1 (maxProperties)"}
]
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