将"true"(JSON)转换为Python等效的"True"

Question

我最近使用的Train状态API (has_arrived, has_departed)在JSON对象中添加了两个额外的键值对,这导致我的脚本崩溃.

这是字典:

{
"response_code": 200,
  "train_number": "12229",
  "position": "at Source",
  "route": [
    {
      "no": 1,
      "has_arrived": false,
      "has_departed": false,
      "scharr": "Source",
      "scharr_date": "15 Nov 2015",
      "actarr_date": "15 Nov 2015",
      "station": "LKO",
      "actdep": "22:15",
      "schdep": "22:15",
      "actarr": "00:00",
      "distance": "0",
      "day": 0
    },
    {
      "actdep": "23:40",
      "scharr": "23:38",
      "schdep": "23:40",
      "actarr": "23:38",
      "no": 2,
      "has_departed": false,
      "scharr_date": "15 Nov 2015",
      "has_arrived": false,
      "station": "HRI",
      "distance": "101",
      "actarr_date": "15 Nov 2015",
      "day": 0
    }
  ]
}

毫不奇怪,我收到以下错误:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'false' is not defined

如果我没有弄错,我认为这是因为JSON响应中的布尔值是false/ true而Python识别False/ True.它有什么办法吗？

PS:我尝试将JSON响应转换has_arrived为字符串,然后将其转换回布尔值,但发现True如果字符串中有任何字符,我将始终获得一个值.我有点被困在这里.

Answer 1

尽管Python的对象声明语法与JSON语法非常相似,但它们是截然不同且不兼容的.除了True/ trueissue之外,还有其他问题(例如Json和Python处理日期的方式非常不同,而python允许注释而Json没有).

解决方案是从一个转换为另一个.

Python的json库可用于在字符串中解析(读取)Json并将其转换为python对象...

data_from_api = '{...}'  # data_from_api should be a string containing your json
info = json.loads(data_from_api)
# info is now a python dictionary (or list as appropriate) representing your Json

你也可以将python对象转换为json ...

info_as_json = json.dumps(info)

例:

# Import the json library
import json

# Get the Json data from the question into a variable...
data_from_api = """{
"response_code": 200,
  "train_number": "12229",
  "position": "at Source",
  "route": [
    {
      "no": 1, "has_arrived": false, "has_departed": false,
      "scharr": "Source",
      "scharr_date": "15 Nov 2015", "actarr_date": "15 Nov 2015",
      "station": "LKO", "actdep": "22:15", "schdep": "22:15",
      "actarr": "00:00", "distance": "0", "day": 0
    },
    {
      "actdep": "23:40", "scharr": "23:38", "schdep": "23:40",
      "actarr": "23:38", "no": 2, "has_departed": false,
      "scharr_date": "15 Nov 2015", "has_arrived": false,
      "station": "HRI", "distance": "101",
      "actarr_date": "15 Nov 2015", "day": 0
    }
  ]
}"""

# Convert that data into a python object...
info = json.loads(data_from_api)
print(info)

第二个例子展示了True/true转换的发生方式.另请注意引用的更改以及如何删除注释...

info = {'foo': True,  # Some insightful comment here
        'bar': 'Some string'}

# Print a condensed representation of the object
print(json.dumps(info))

# Or print a formatted version which is more human readable but uses more bytes
print(json.dumps(info, indent=2))

输出:

{"bar": "Some string", "foo": true}
{
  "bar": "Some string",
  "foo": true
}

Answer 2

不要根据eval答案进行操作，而是使用该json模块。

Answer 3

您还可以使用该值对布尔值进行强制转换。例如，假设您的数据名为“json_data”：

value = json_data.get('route')[0].get('has_arrived') # this will pull "false" into *value

boolean_value = bool(value == 'true') # resulting in False being loaded into *boolean_value

这有点像hackey，但它有效。

Answer 4

可以利用 Python 的布尔值来表示 int、str、list 等。

例如：

bool(1)     # True
bool(0)     # False

bool("a")   # True
bool("")    # False

bool([1])   # True
bool([])    # False

在 Json 文件中，您可以设置

"has_arrived": 0,

然后在你的Python代码中

if data["has_arrived"]:
    arrived()
else:
    not_arrived()

这里的问题是不要混淆代表 False 的 0 和代表其值的 0。