棉花糖父架构 - 如何在子架构之间共享验证修饰器

Question

我有一个父棉花糖模式"ParentSchema"和2个嵌套的子模式"ChildSchema1"和"ChildSchema2"。两个嵌套子架构都利用 @validates_schema 修饰器从棉花糖进行字段验证。它们看起来像这样：

ParenSchema.py

from marshmallow import Schema, fields
from schemas.childSchema1 import ChildSchema1
from schemas.childSchema2 import ChildSchema2
    class ParentSchema(Schema):
        child1 = fields.Nested(ChildSchema1)
        child2 = fields.Nested(ChildSchema2)
        foo = fields.String()
        bar = fields.String()

ChildSchema1.py

from marshmallow import Schema, pprint, post_load
from marshmallow import fields, ValidationError, validates, validates_schema
class ChildSchema1(Schema):
    field1 = fields.String()
    field2 = fields.String()
    common_field = fields.String()
    @validates("common_field")
    def validate_common_field(self, common_field):
        try:
            # Validation logic
        except:
            raise ValidationError('common_field is not valid')

ChildSchema2.py

from marshmallow import Schema, pprint, post_load
from marshmallow import fields, ValidationError, validates, validates_schema
class ChildSchema2(Schema):
    common_field = fields.String()
    field3 = fields.String()
    @validates("common_field")
    def validate_common_field(self, common_field):
        try:
            # Exact Same Validation logic as common_field from ChildSchema1
        except:
            raise ValidationError('common_field is not valid')

鉴于 ChildSchema1 和 ChildSchema2 都有一个同名的字段，具有相同的验证器函数，我很想遵循 DRY 原则并将该函数拉出 ParentSchema.py。

Answer 1

我发现的一个解决方案是创建一个单独的类来托管共享验证函数：

def validate_common_field(self, common_field):
    try:
        # Exact Same Validation logic as common_field from ChildSchema1
    except:
        raise ValidationError('common_field is not valid')

并通过删除@validates装饰器并在架构字段中使用 validate 参数来从 ChildSchema1 和 ChildSchema2 中使用它，如下所示。

ChildSchema1.py

from marshmallow import Schema, pprint, post_load
from marshmallow import fields, ValidationError, validates, validates_schema
from validators import *
class ChildSchema1(Schema):
    field1 = fields.String()
    field2 = fields.String()
    common_field = fields.String(validate=validate_common_field)

validators.py 从棉花糖导入验证错误，验证

def validate_common_field(self, common_field):
        try:
            # Validation logic
        except:
            raise ValidationError('common_field is not valid')

Answer 2

您使用单独函数的方法很好。

如果公共字段由两个子字段共享，则还可以使用继承来反映这一点，并对字段和逻辑进行分解。

class ChildSchema(Schema):
    common_field = fields.String()
    @validates("common_field")
    def validate_common_field(self, common_field):
        try:
            # Validation logic
        except:
            raise ValidationError('common_field is not valid')
class ChildSchema1(ChildSchema):
    field1 = fields.String()
    field2 = fields.String()
class ChildSchema2(ChildSchema):
    field3 = fields.String()