[英]Python List Comprehension to Delete Dict in List
{
"Credentials": [
{
"realName": "Jimmy John",
"toolsOut": null,
"username": "291R"
},
{
"realName": "Grant Hanson",
"toolsOut": null,
"username": "98U9"
},
{
"realName": "Gill French",
"toolsOut": null,
"username": "F114"
}
]
}
我有一个格式如上的 json 文件,我试图让 function 根据用户输入的用户名删除一个条目。 我希望文件被删除的条目覆盖。
我试过这个:
def removeUserFunc(SID):
print(SID.get())
with open('Credentials.json','r+') as json_file:
data = json.load(json_file)
data['Credentials'][:] = [item for item in data['Credentials'] if item['username'] != SID.get()]
json_file.seek(0)
json.dump(data,json_file,indent=3,sort_keys=True)
它部分工作,因为 Credentials 部分中的所有内容看起来都很正常,但它在末尾附加了一个奇怪的复制片段,打破了 JSON。假设我正在删除 Grant 并运行此代码,我的 JSON 如下所示:
{
"Credentials": [
{
"realName": "Marcus Koga",
"toolsOut": null,
"username": "291F"
},
{
"realName": "Gill French",
"toolsOut": null,
"username": "F114"
}
]
} "realName": "Gill French",
"toolsOut": null,
"username": "F114"
}
]
}
我对 Python 和编辑 JSON 比较陌生。
您需要在写入后截断文件:
def removeUserFunc(SID):
print(SID.get())
with open('Credentials.json','r+') as json_file:
data = json.load(json_file)
data['Credentials'][:] = [item for item in data['Credentials'] if item['username'] != SID.get()]
json_file.seek(0)
json.dump(data,json_file,indent=3,sort_keys=True)
json_file.truncate()
您可以关闭文件,然后以只写方式打开文件,这将在写入新内容之前清除原始文件的内容。例如:
def removeUserFunc(SID):
# open file for reading
with open('Credentials.json','r') as json_file:
# read the data to variable:
data = json.load(json_file)
# open file for writing:
with open('Credentials.json','w') as json_file:
data['Credentials'][:] = [item for item in data['Credentials'] if item['username'] != SID.get()]
json.dump(data,json_file,indent=3,sort_keys=True)
file.seek(0)
只是移动文件指针但不改变文件的长度。 因此,如果您不覆盖文件的全部内容,您将留下残留内容。 在写入之前使用file.truncate()
将文件长度设置为零。
json_file.seek(0)
json_file.truncate() # set file length to zero
json.dump(data,json_file,indent=3,sort_keys=True)
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