Python marshmallow.fields 模块，Decimal() 实例源码

def resolve_numeric_string_field(field):
    """
    Numeric fields should respect the `as_string` parameter.

    """
    if isinstance(field, fields.Decimal):
        return dict(
            type="string",
            format="decimal",
        )
    else:
        return dict(
            type="string",
        )