python-3.x - 附加到 pickle 文件而不删除

Question

我尝试使用 pickle 模块使用二进制模式写入文件。这是一个例子:

    import pickle
    file = open("file.txt","wb")
    dict = {"a":"b","c":"d"}
    pickle.dump(dict, file)
    file.close()

但是这个方法删除了之前写的其他dicts。如何在不删除文件中其他内容的情况下写入？

Answer 1

您需要附加到原始文件，但首先要解开内容(我假设原始文件有已 pickle 的内容)。您所做的只是用新的 pickle 对象覆盖现有文件

import pickle

#create the initial file for test purposes only
obj = {"a":"b","c":"d"}
with open("file.txt","wb") as f:
    pickle.dump(obj, f)

#reopen and unpickle the pickled content and read to obj
with open("file.txt","rb") as f:
    obj = pickle.load(f)
    print(obj)

#add to the dictionary object 
obj["newa"]="newb"
obj["newc"]="newd"

with open("file.txt","wb") as f:
    pickle.dump(obj, f)

#reopen and unpickle the pickled content and read to obj
with open("file.txt","rb") as f:
    obj = pickle.load(f)
    print(obj)