python-jsonstore 1.1.2

基础知识

# by default JsonStore commits on every change unless in a transactionstore=JsonStore('config.json')store.a_string="something"store.a_list=[1,2,3]store.a_dictionary={'dict-list':[{}],'ln(2)':0.69314718056,'for-you':u"?",}# you can use […] to set/get/delete string keysstore['some_key']="a value"# the key is split on '.'s and works on dictionariesdelstore['a_dictionary.dict-list']store['a_dictionary.new_value']="old value"#  you can also use the syntactic sugar for tuple keys (explicit lists work too)assertstore['a_dictionary','new_value']=="old value"# you can traverse lists tooassertstore['a_list',-1]==3# you can use slices in listsassertlen(store['a_list',1:])==2# deep copies are made when assigning valuesmy_list=['fun']store.a_list=my_listassertstore.a_listisnotmy_listassert'a_list'instore# deep copies are also returned to avoid unsanitary changes being madestore.a_dictionary['new_value']="new value"# won't update the store!assertstore.a_dictionary['new_value']=="old value"assertstore.a_dictionaryisnotstore.a_dictionary

交易

JsonStore对象可以用作context managers来提供 在发生异常时回滚的事务。这个 事务模型是原始的；您只能嵌套事务。

当将存储放入事务中时，它不会将更改保存到 在所有交易结束前归档。

fromjsonstoreimportJsonStore# even with auto_commit=True, the file won't be saved until the last contexts has been closedwithJsonStore('config.json',indent=None,auto_commit=False)asstore:self.value=1# the context manager will roll back changes made if an exception is raisedstore=JsonStore('config.json',indent=None)try:withstore:store.value="new"raiseExceptionexceptException:pass# here we see the value that was saved previouslyassertstore.value==1