refactor: set default meta values to None (null)

# meta字段和默认值

REQUIRED_KEYS_IN_META = dict(

    # 编排信息

    dataset="null",

    instrument="null",

    obs_type="null",

    obs_group="null",

    obs_id="null",

    dataset=None,

    instrument=None,

    obs_type=None,

    obs_group=None,

    obs_id=None,

    # 探测信息

    detector="null",

    filter="null",

    detector=None,

    filter=None,

    # 参考信息

    pmapname="null",

    ref_cat="null",

    pmapname=None,

    ref_cat=None,

    # 数据处理信息

    custom_id="null",

    batch_id="null",

    dag_group="null",

    dag_group_run="null",

    dag="null",

    dag_run="null",

    custom_id=None,

    batch_id=None,

    dag_group=None,

    dag_group_run=None,

    dag=None,

    dag_run=None,

    priority=-1,

    data_list=[],

    extra_kwargs={},

    created_time="1970-01-01T00:00:00.000",

    rerun=-1,

    # 数据产品信息

    data_model="null",  # 数据产品类型，手动设置

    data_uuid="null",  # UUID，自动设置

    data_model=None,  # 数据产品类型，手动设置

    data_uuid=None,  # UUID，自动设置

    qc_status=-1024,  # QC状态

    # Docker镜像名称和版本

    docker_image="null",  # 镜像名称，自动设置

    build="null",  # 镜像版本，自动设置

    docker_image=None,  # 镜像名称，自动设置

    build=None,  # 镜像版本，自动设置

    # 额外的观测筛选参数

    object="null",  # 观测目标

    proposal_id="null",  # 观测申请ID

    object=None,  # 观测目标

    proposal_id=None,  # 观测申请ID

    ra=-3.141592653589793,  # 赤经

    dec=-3.141592653589793,  # 赤纬

    healpix=-1,  # HEALPix，每种数据产品的nside可以不一样

        else:

            raise KeyError(f"未知的meta参数: {k}")

    # automatically set docker_image, build, and created_date

    meta["docker_image"] = os.getenv("PIPELINE_ID", default="null")

    meta["build"] = os.getenv("BUILD", default="null")

    meta["docker_image"] = os.getenv("PIPELINE_ID", default=None)

    meta["build"] = os.getenv("BUILD", default=None)

    meta["prc_date"] = now()

    meta["data_uuid"] = str(uuid.uuid4())

    return meta

def get_proc_info(**kwargs):

    cards = [("BUILD", os.getenv("BUILD", default="null"), "")]

    cards = [("BUILD", os.getenv("BUILD", default=""), "")]

    for k, v in kwargs.items():

        cards.append((k, v, ""))

    header = fits.Header(cards=cards)