python construct 字符串_通过字符串变量在Python中设置和获取@property方法
目前我有一個通用函數(shù),你可以傳入一個屬性名和一個類(它也適用于特定的對象實例,但我正在使用類),該函數(shù)將通過調(diào)用查找并操作該屬性
getattr(model_class, model_attribute)
它將通過調(diào)用(此時在對象實例上)來修改屬性
settattr(model_obj,key,value)
但是,我有一個類,我們定義了@property方法而不是簡單屬性,并且setattr不起作用.如何基于該屬性方法的字符串名稱動態(tài)獲取@property?
也許我可以使用__dict__,但這看起來很臟而且不那么安全.
編輯:示例代碼
廣義函數(shù)
def process_general(mapping, map_keys, model_class, filter_fn, op_mode=op_modes.UPDATE):
"""
Creates or updates a general table object based on a config dictionary.
`mapping`: a configuration dictionary, specifying info about the table row value
`map_keys`: keys in the mapping that we use for the ORM object
`model_class`: the ORM model class we use the config data in
`op_mode`: the kind of operation we want to perform (delete, update, add, etc.)
Note that relationships between model objects must be defined and connected
outside of this function.
"""
# We construct a dictionary containing the values we need to set
arg_dict = make_keyword_args(map_keys, mapping)
# if we are updating, then we must first check if the item exists
# already
if (op_mode == op_modes.UPDATE):
# Find all rows that match by the unique token.
# It should only be one, but we will process all of them if it is the
# case that we didn't stick to the uniqueness requirement.
matches = filter_fn()
# Keep track of the length of the iterator so we know if we need to add
# a new row
num_results = 0
for match in matches:
# and we set all of the object attributes based on the dictionary
set_attrs_from_dict(match, arg_dict)
model_obj = match
num_results += 1
# We have found no matches, so just add a new row
if (num_results < 1):
model_obj = model_class(**arg_dict)
return model_obj
# TODO add support for other modes. This here defaults to add
else:
return model_class(**arg_dict)
傳入的示例類:
class Dataset(db.Model, UserContribMixin):
# A list of filters for the dataset. It can be built into the dataset filter form dict
# in get_filter_form. It's also useful for searching.
filters = db.relationship('DatasetFilter', backref='dataset')
# private, and retrieved from the @property = select
_fact_select = db.relationship('DatasetFactSelect', order_by='DatasetFactSelect.order')
@property
def fact_select(self):
"""
FIXME: What is this used for?
Appears to be a list of strings used to select (something) from the
fact model in the star dataset interface.
:return: List of strings used to select from the fact model
:rtype: list
"""
# these should be in proper order from the relationship order_by clause
sels = [sel.fact_select for sel in self._fact_select]
return sels
總結(jié)
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