PyPI 官网下载 | mappr-0.1.20.tar.gz

from typing import Any from . import types def map_directly(src_obj: Any, name: str) -> Any: if not hasattr(src_obj, name): cls_name = src_obj.__class__.__name__ raise ValueError(f"{cls_name} does not have '{name}' property.") return getattr(src_obj, name) def set_const(value: Any) -> types.MappingFn: """ Always set the field to the given value during conversion. You can use `mappr.set_const` if you want to set an attribute to a constant value during conversion, without concern about the source object. Every call to `mappr.convert` will return the same *value*. Args: value: The value to set on the field. Instead of using the source object attribute or target type field default, this value will be set on the field during conversion. Returns: A mapping function. Example: >>> from dataclasses import dataclass >>> import mappr >>> >>> @dataclass ... class Src: ... text: str = 'hello' ... num: int = 10 >>> >>> @dataclass ... class Dst: ... text: str ... num: int = 20 >>> >>> mappr.register(Src, Dst, mapping=dict( ... num=mappr.set_const(100) ... )) >>> >>> src = Src() >>> dst = mappr.convert(Dst, src) >>> >>> dst.text 'hello' >>> dst.num 100 """ def mapper(src_obj: Any, name: str) -> Any: return value return mapper def use_default(src_obj: Any, name: str) -> Any: """ Indicate we want to use default field value rather than value from source object Args: src_obj: The converted object. Not used here, but part of the mappers interface so has to be defined. name: l Name of the converted field. Not used here, but part of the mappers interface. Returns: A mapping function for the field. This is just a stub, as `mappr.convert` will just skip the field if it's mapper is set to `mappr.use_default`. By default, if the attribute exists on the source object, it's value will be used when creating the result. That happens even if the destination type defines a default value for that field. If you want to use the default provided by the target type you can achive that with `mappr.use_default` mapper. You simply set the field to `mappr.use_default` and the attribute value from the source object won't be used (the target default is used). If the target type does not define a default value an exception will be raised during the creation of the final result. Example: >>> from dataclasses import dataclass >>> import mappr >>> >>> @dataclass ... class Src: ... text: str = 'hello' ... num: int = 10 >>> >>> @dataclass ... class Dst: ... text: str ... num: int = 20 >>> >>> mappr.register(Src, Dst, mapping=dict( ... num=mappr.use_default ... )) >>> >>> src = Src() >>> dst = mappr.convert(Dst, src) >>> >>> dst.text 'hello' >>> dst.num 20 """ return lambda src_obj, name: None # nocov