如果尚未将数据附加到 json 文件中[重复]

Question

我有一个 .json 文件，我想将数据附加到该文件中。但前提是此字符串不在 .json 文件中。

JSON 文件：

[{"filename":"file1"}, {"filename":"file2"}, {"filename":"file3"}]

最终结果 JSON 文件：

[{"filename":"file1"}, {"filename":"file2"}, {"filename":"file3"}, {"filename":"file4"}]

我目前有这个：

with open('gdrivefiles.json', 'r') as f:
     filenameslist = json.load(f)    #Loads the .json file into a string (If I'm right)
for distro in filenameslist:
     filenames = distro["filename"]  #Gets a list of all the filenames

if name in filenames:
   print("yes")                      #If name is in the list of filenames print 'yes'
else:
   print("no")                       #If name is in the list of filenames print 'no'

（这段代码放在一个for循环中，所以它会为name的每个新值运行这段代码）

如果 json 文件中还没有 name ({"filename":"name"})，我该如何添加它？

Answer 1

这段代码应该做你想做的：

import json

new_file = {"filename":"name"}

data = json.load(open("data.json"))
if not any([new_file['filename'] == x['filename'] for x in data]):
    data.append(new_file)

    json.dump(data, open("data.json","w"))

Answer 2

只需要在回写时创建数据结构：

import json

name = "file4"
with open('gdrivefiles.json', 'r') as f:
    filenameslist = json.load(f)

filenames = [distro["filename"] for distro in filenameslist]

if name in filenames:
    print("yes")                      #If name is in the list of filenames print 'yes'
else:
    print("no")                       #If name is in the list of filenames print 'no'
    filenames.append(name)

#  write filenames back to file as list of dicts!
with open('gdrivefiles.json', 'w') as f:
    f.write(json.dumps([{'filename': name} for name in filenames]))

Answer 3

import json

new_object = {"filename":"file5"}

with open('data.json') as json_file:
    data = json.load(json_file)
    if new_object not in data: 
      data.append(new_object)        
      json_file.close()

with open('data.json', 'w') as outfile:
   json.dump(data, outfile)
   outfile.close()