将 dictionary 转换为 JSON

json.dumps()返回python字典的JSON字符串表示形式。查看文档

你不能做r['rating']，因为r是一个字符串，不再是字典

也许你的意思是

r = {'is_claimed': 'True', 'rating': 3.5}
json = json.dumps(r) # note i gave it a different name
file.write(str(r['rating']))

不需要使用json.dumps()将其转换为字符串

r = {'is_claimed': 'True', 'rating': 3.5}
file.write(r['is_claimed'])
file.write(str(r['rating']))

可以直接从dict对象中获取值。

json.dumps()将字典转换为str对象，而不是json(dict)对象!所以你必须将你的str加载到一个dict中，通过使用< >强json.loads() < / >强方法来使用它

将json.dumps()作为保存方法，将json.loads()作为检索方法。

下面是代码示例，可以帮助你更好地理解它:

import json


r = {'is_claimed': 'True', 'rating': 3.5}
r = json.dumps(r)
loaded_r = json.loads(r)
loaded_r['rating'] #Output 3.5
type(r) #Output str
type(loaded_r) #Output dict

将r定义为字典可以达到这个目的:

>>> r: dict = {'is_claimed': 'True', 'rating': 3.5}
>>> print(r['rating'])
3.5
>>> type(r)
<class 'dict'>

json.dumps()用于解码JSON数据

• json.loads接受字符串作为输入，并返回一个字典作为输出。
• json.dumps接受字典作为输入，并返回一个字符串作为输出。

import json


# initialize different data
str_data = 'normal string'
int_data = 1
float_data = 1.50
list_data = [str_data, int_data, float_data]
nested_list = [int_data, float_data, list_data]
dictionary = {
'int': int_data,
'str': str_data,
'float': float_data,
'list': list_data,
'nested list': nested_list
}


# convert them to JSON data and then print it
print('String :', json.dumps(str_data))
print('Integer :', json.dumps(int_data))
print('Float :', json.dumps(float_data))
print('List :', json.dumps(list_data))
print('Nested List :', json.dumps(nested_list, indent=4))
print('Dictionary :', json.dumps(dictionary, indent=4))  # the json data will be indented

输出:

String : "normal string"
Integer : 1
Float : 1.5
List : ["normal string", 1, 1.5]
Nested List : [
1,
1.5,
[
"normal string",
1,
1.5
]
]
Dictionary : {
"int": 1,
"str": "normal string",
"float": 1.5,
"list": [
"normal string",
1,
1.5
],
"nested list": [
1,
1.5,
[
"normal string",
1,
1.5
]
]
}

• Python对象到JSON数据转换

|                 Python                 |  JSON  |
|:--------------------------------------:|:------:|
|                  dict                  | object |
|               list, tuple              |  array |
|                   str                  | string |
| int, float, int- & float-derived Enums | number |
|                  True                  |  true  |
|                  False                 |  false |
|                  None                  |  null  |

更新

在JSON文件中

nested_dictionary = {
'one': nested_list,
'two': dictionary,


}


json_dict = {'Nested Dictionary': nested_dictionary,
'Multiple':[nested_dictionary, nested_dictionary, nested_dictionary]
}


with open("test_nested.json", "w") as outfile:
json.dump(json_dict, outfile, indent=4, sort_keys=False)

图表反应

输出到test_nested.json

{
"Nested Dictionary": {
"one": [
1,
1.5,
[
"normal string",
1,
1.5
]
],
"two": {
"int": 1,
"str": "normal string",
"float": 1.5,
"list": [
"normal string",
1,
1.5
],
"nested list": [
1,
1.5,
[
"normal string",
1,
1.5
]
]
}
},
"Multiple": [
{
"one": [
1,
1.5,
[
"normal string",
1,
1.5
]
],
"two": {
"int": 1,
"str": "normal string",
"float": 1.5,
"list": [
"normal string",
1,
1.5
],
"nested list": [
1,
1.5,
[
"normal string",
1,
1.5
]
]
}
},
{
"one": [
1,
1.5,
[
"normal string",
1,
1.5
]
],
"two": {
"int": 1,
"str": "normal string",
"float": 1.5,
"list": [
"normal string",
1,
1.5
],
"nested list": [
1,
1.5,
[
"normal string",
1,
1.5
]
]
}
},
{
"one": [
1,
1.5,
[
"normal string",
1,
1.5
]
],
"two": {
"int": 1,
"str": "normal string",
"float": 1.5,
"list": [
"normal string",
1,
1.5
],
"nested list": [
1,
1.5,
[
"normal string",
1,
1.5
]
]
}
}
]
}

class实例转换为JSON

• 一个简单的解决方案:

class Foo(object):
def __init__(
self,
data_str,
data_int,
data_float,
data_list,
data_n_list,
data_dict,
data_n_dict):
self.str_data = data_str
self.int_data = data_int
self.float_data = data_float
self.list_data = data_list
self.nested_list = data_n_list
self.dictionary = data_dict
self.nested_dictionary = data_n_dict




foo = Foo(
str_data,
int_data,
float_data,
list_data,
nested_list,
dictionary,
nested_dictionary)


# Because the JSON object is a Python dictionary.
result = json.dumps(foo.__dict__, indent=4)
# See table above.


# or with built-in function that accesses .__dict__ for you, called vars()
# result = json.dumps(vars(foo), indent=4)


print(result) # same as before

• 更简单的

class Bar:
def toJSON(self):
return json.dumps(self, default=lambda o: o.__dict__,
sort_keys=False, indent=4)




bar = Bar()
bar.web = "Stackoverflow"
bar.type = "Knowledge"
bar.is_the_best = True
bar.user = Bar()
bar.user.name = "Milovan"
bar.user.age = 34


print(bar.toJSON())

图表反应

输出:

{
"web": "Stackoverflow",
"type": "Knowledge",
"is_the_best": true,
"user": {
"name": "Milovan",
"age": 34
}
}

在上面的例子中，您可以通过在默认字典中声明一个新字典来创建一个嵌套字典。

import json
dictionary = {
'fruit':{"Grapes": "10","color": "green"},
'vegetable':{"chilli": "4","color": "red"},
}
result = json.dumps(dictionary, indent = 3)

打印(结果)

这里，我使用了indent=3

参考:https://favtutor.com/blogs/dict-to-json-python