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将JSON转换为Python字典

pythondjangojsondictionary
26

我一直在四处搜索寻找这个问题的答案，但似乎无法找到。也许已经太晚了，难以找到答案，所以我转向这里优秀的读者们。

我正在从CouchDB记录中提取以下JSON数据：

"{\"description\":\"fdsafsa\",\"order\":\"1\",\"place\":\"22 Plainsman Rd, Mississauga, ON, Canada\",\"lat\":43.5969175,\"lng\":-79.7248744,\"locationDate\":\"03/24/2010\"},{\"description\":\"sadfdsa\",\"order\":\"2\",\"place\":\"50 Dawnridge Trail, Brampton, ON, Canada\",\"lat\":43.7304774,\"lng\":-79.8055435,\"locationDate\":\"03/26/2010\"},"

这些数据被存储在名为'my_plan'的字典中，键名为'locations'。我想将这些数据从CouchDB转换成Python字典，以便在Django模板中执行以下操作:

{% for location in my_plan.locations %}                                                           
<tr>
    <td>{{ location.place }}</td>
    <td>{{ location.locationDate }}</td>
</tr>

{% endfor %}

我在转换字典为JSON方面已经找到了很多信息，但是没有关于反向转换的。

6个回答
39

  • 使用json模块来加载JSON。（对于2.6之前的版本，请使用第三方的simplejson模块，它具有完全相同的API。）

>>> import json
>>> s = '{"foo": 6, "bar": [1, 2, 3]}'
>>> d = json.loads(s)
>>> print d
{u'foo': 6, u'bar': [1, 2, 3]}

  • 因为实际数据是由两个JSON对象组成，它们之间用逗号分隔并以逗号结尾，所以无法通过这种方式加载。您需要将它们分开或以其他方式处理。

    • 您从哪里获取了此字符串？
    • 那个字符串来自我正在开发的应用程序生成的数据，这是一种针对计划旅行、酒吧爬行等活动的位置和日期社交应用程序。 - GrumpyCanuck
    20
    你展示的字符串不是一个JSON编码的对象（相当于Python字典）——更像是一个缺少括号且末尾有一个多余逗号的数组（相当于列表）。所以（为了版本可移植性，可以使用simplejson，当然在2.6中，标准库的json也可以使用!-）：
    >>> import simplejson
>>> js = "{\"description\":\"fdsafsa\",\"order\":\"1\",\"place\":\"22 Plainsman Rd, Mississauga, ON, Canada\",\"lat\":43.5969175,\"lng\":-79.7248744,\"locationDate\":\"03/24/2010\"},{\"description\":\"sadfdsa\",\"order\":\"2\",\"place\":\"50 Dawnridge Trail, Brampton, ON, Canada\",\"lat\":43.7304774,\"lng\":-79.8055435,\"locationDate\":\"03/26/2010\"},"
>>> simplejson.loads('[%s]' % js[:-1])
[{'description': 'fdsafsa', 'order': '1', 'place': '22 Plainsman Rd, Mississauga, ON, Canada', 'lat': 43.596917500000004, 'lng': -79.724874400000004, 'locationDate': '03/24/2010'}, {'description': 'sadfdsa', 'order': '2', 'place': '50 Dawnridge Trail, Brampton, ON, Canada', 'lat': 43.730477399999998, 'lng': -79.805543499999999, 'locationDate': '03/26/2010'}]

    如果你真的想要一个字典，你需要指定如何处理这两个未命名的项，也就是你想要添加什么任意键？

    1
    你的解决方案完美地运行了。谢谢！在将数据放入CouchDB之前，我会修复生成数据的程序，以便不再添加额外的逗号。这是一些深夜编码的疏忽。 - GrumpyCanuck
    1
    @Grumpy，当然-如果我是你，我也会在数据库中的字符串周围加上括号，以确保它是有效的JSON，而不是接收代码必须完成的“有些不完整的JSON”。 - Alex Martelli
    1
    我以前做过那件事，但不记得为什么停止了...我想从现在开始，深夜编程需要笔记。 - GrumpyCanuck
    为什么不使用json模块呢？simplejson已经过时了，应该在很久以前就被弃用了。请查看下面的答案 :) - holms
    2
    django.utils.simplejson.loads(someJson)
    1
    不要将其转换为字典。我尝试过了 ;) - GrumpyCanuck
    它实际给出的错误是“额外的数据：第1行第151列 - 第1行第304列（字符151-304）” - GrumpyCanuck
    1
    @GrumpyCanuck，仔细看。这不是一个对象。它是一个对象，然后是逗号，然后是另一个对象，再然后是逗号。 - Mike Graham
    是的，当我看到@Alex Martelli的回答时，我就明白了。 - GrumpyCanuck
    0
    Hello here my example
import json
class SimpleObject(object):
    def __init__(self, _dict):
        self.__dict__.update(_dict)

data=json.loads("{\"name\":\"Rishikesh Agrawani\", \"age\": 25}" )  
so=SimpleObject(data)
print (so.name)
print (so.age)

if you transform your data to objects is better and more fast work.
    0

    以下是其他答案的结合：

    import json
yourString = "{\"description\":\"fdsafsa\",\"order\":\"1\",\"place\":\"22 Plainsman Rd, Mississauga, ON, Canada\",\"lat\":43.5969175,\"lng\":-79.7248744,\"locationDate\":\"03/24/2010\"},{\"description\":\"sadfdsa\",\"order\":\"2\",\"place\":\"50 Dawnridge Trail, Brampton, ON, Canada\",\"lat\":43.7304774,\"lng\":-79.8055435,\"locationDate\":\"03/26/2010\"},"
target = json.loads("[" + yourString[:-1] + "]")

    输出

    [{u'description': u'fdsafsa', u'order': u'1', u'place': u'22 Plainsman Rd, Mississauga, ON, Canada', u'lat': 43.5969175, u'lng': -79.7248744, u'locationDate': u'03/24/2010'}, {u'description': u'sadfdsa', u'order': u'2', u'place': u'50 Dawnridge Trail, Brampton, ON, Canada', u'lat': 43.7304774, u'lng': -79.8055435, u'locationDate': u'03/26/2010'}]

    如上所述

    • 该字符串包含两个JSON对象，因此将其放入一个数组中（[]）
    • 它有一个尾随的,，可以通过[:-1]切片语法移除
    0

    首先，要做的是第一件事。

    在这里，我已经将您提取的数据字符串存储到一个名为data_str的变量中，其中包含两个字典。

    >>> data_str = "{\"description\":\"fdsafsa\",\"order\":\"1\",\"place\":\"22 Plainsman Rd, Mississauga, ON, Canada\",\"lat\":43.5969175,\"lng\":-79.7248744,\"locationDate\":\"03/24/2010\"},{\"description\":\"sadfdsa\",\"order\":\"2\",\"place\":\"50 Dawnridge Trail, Brampton, ON, Canada\",\"lat\":43.7304774,\"lng\":-79.8055435,\"locationDate\":\"03/26/2010\"},"

    然后我将它转换成另一个名为data_str2的字符串，它是以列表形式存在的，并从最后移除了额外的逗号(,)（因为在将字符串数据转换为Python对象时会出现错误）。

    >>> data_str2 = "[" + data_str[0: 1] + data_str[1: len(data_str)-1] + "]"

    最后，我将这个包含两个字典的列表字符串转换成原始的Python列表，并将其存储在一个名为data_list的变量中。
    >>> import json
>>> data_list = json.loads(data_str2) # Now data_list is a list having 2 dictionaries

    现在让我们打印我们的数据。

    >>> print data_list
[{u'description': u'fdsafsa', u'order': u'1', u'place': u'22 Plainsman Rd, Mississauga, ON, Canada', u'lat': 43.5969175, u'lng': -79.7248744, u'locationDate': u'03/24/2010'}, {u'description': u'sadfdsa', u'order': u'2', u'place': u'50 Dawnridge Trail, Brampton, ON, Canada', u'lat': 43.7304774, u'lng': -79.8055435, u'locationDate': u'03/26/2010'}]
>>> 
>>> print type(data_list)
<type 'list'>
>>> 
>>> print data_list[0]
{u'description': u'fdsafsa', u'order': u'1', u'place': u'22 Plainsman Rd, Mississauga, ON, Canada', u'lat': 43.5969175, u'lng': -79.7248744, u'locationDate': u'03/24/2010'}
>>> 
>>> print data_list[1]
{u'description': u'sadfdsa', u'order': u'2', u'place': u'50 Dawnridge Trail, Brampton, ON, Canada', u'lat': 43.7304774, u'lng': -79.8055435, u'locationDate': u'03/26/2010'}
>>>

    将这个名为data_list的列表从视图中传递，并在您的Django模板中按如下方式访问：
    {% for data in locations %}
      <tr>
           <td> {{ data.place }} </td>
           <td> {{ data.locationDate }} </td>
      </tr>
{% endfor %}

    以下是一个代码片段，供您参考。

    def locations(request):
    # YOU HAVE TO WRITE YOUR CODE LOGIC HERE TO GET THE LIST, 
    # I AM WRITING IT DIRECTLY
    data_list = [{u'description': u'fdsafsa', u'order': u'1', u'place': u'22 Plainsman Rd, Mississauga, ON, Canada', u'lat': 43.5969175, u'lng': -79.7248744, u'locationDate': u'03/24/2010'}, {u'description': u'sadfdsa', u'order': u'2', u'place': u'50 Dawnridge Trail, Brampton, ON, Canada', u'lat': 43.7304774, u'lng': -79.8055435, u'locationDate': u'03/26/2010'}]
    return render(request, "locations.html", {"locations": data_list})

    它运行得很好。

    现在我想要解释一下我是如何达到这个解决方案的，我认为这对初学者会有所帮助。请看下面逐步解释的过程或在这里查看。

    >>> import json   
>>>
>>> # A simple attempt
>>> s = "{\"description\":\"fdsafsa\"}"
>>> python_dict = json.loads(s)
>>> python_dict
{u'description': u'fdsafsa'}
>>> # Accessing value using key
>>> python_dict["description"]
u'fdsafsa'
>>> 
>>> # It worked, lets test our given string containing 2 dictionaries(in string form) one by one
>>> # Converting 1st JSON string to Dict
>>> s2 = "{\"description\":\"fdsafsa\",\"order\":\"1\",\"place\":\"22 Plainsman Rd, Mississauga, ON, Canada\",\"lat\":43.5969175,\"lng\":-79.7248744,\"locationDate\":\"03/24/2010\"}"
>>> python_dict2 = json.loads(s2)                                                                                      >>> python_dict2
{u'description': u'fdsafsa', u'order': u'1', u'place': u'22 Plainsman Rd, Mississauga, ON, Canada', u'lat': 43.5969175, u'lng': -79.7248744, u'locationDate': u'03/24/2010'}
>>> 
>>> # Converting 2nd JSON string to Dict
>>> # remove comma(,) from end otherwise you will get the following error
>>> s3 = "{\"description\":\"sadfdsa\",\"order\":\"2\",\"place\":\"50 Dawnridge Trail, Brampton, ON, Canada\",\"lat\":43.7304774,\"lng\":-79.8055435,\"locationDate\":\"03/26/2010\"},"
>>> python_dict3 = json.loads(s3)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 339, in loads
    return _default_decoder.decode(s)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 367, in decode
    raise ValueError(errmsg("Extra data", s, end, len(s)))
ValueError: Extra data: line 1 column 152 - line 1 column 153 (char 151 - 152)
>>> 
>>> # Now I removed comma(,) from end and retried, it worked
>>> s3 = "{\"description\":\"sadfdsa\",\"order\":\"2\",\"place\":\"50 Dawnridge Trail, Brampton, ON, Canada\",\"lat\":43.7304774,\"lng\":-79.8055435,\"locationDate\":\"03/26/2010\"}"
>>> python_dict3 = json.loads(s3) 
>>> 
>>> # So now we knew that we have not to include any extra comma at end in the string form of JSON
>>> # For example (Correct form)
>>> details_str = "{\"name\":\"Rishikesh Agrawani\", \"age\": 25}" 
>>> details_dict = json.loads(details_str)
>>> details_dict["name"]
u'Rishikesh Agrawani'
>>> details_dict["age"]
25
>>> # Now (Incorrect form), here comma(,) is at end, just after } 
>>> details_str = "{\"name\":\"Rishikesh Agrawani\", \"age\": 25},"
>>> details_dict = json.loads(details_str)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 339, in loads
    return _default_decoder.decode(s)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 367, in decode
    raise ValueError(errmsg("Extra data", s, end, len(s)))
ValueError: Extra data: line 1 column 41 - line 1 column 42 (char 40 - 41)
>>> 
>>> # The problem is the string does not denote any single python object 
>>> # So we will convert the string into a list form by appending [ at beginning and ] at end
>>> # Now our string will denote a single Python object that is list of 2 dictioanaries
>>> # Lets do this, here I am storing the given string into variable s4
>>> data_str = "{\"description\":\"fdsafsa\",\"order\":\"1\",\"place\":\"22 Plainsman Rd, Mississauga, ON, Canada\",\"lat\":43.5969175,\"lng\":-79.7248744,\"locationDate\":\"03/24/2010\"},{\"description\":\"sadfdsa\",\"order\":\"2\",\"place\":\"50 Dawnridge Trail, Brampton, ON, Canada\",\"lat\":43.7304774,\"lng\":-79.8055435,\"locationDate\":\"03/26/2010\"},"
>>> s5 = "[" + s4[0:1] + s4[1: len(s4)-1] + "]"
>>> s5
'[{"description":"fdsafsa","order":"1","place":"22 Plainsman Rd, Mississauga, ON, Canada","lat":43.5969175,"lng":-79.7248744,"locationDate":"03/24/2010"},{"description":"sadfdsa","order":"2","place":"50 Dawnridge Trail, Brampton, ON, Canada","lat":43.7304774,"lng":-79.8055435,"locationDate":"03/26/2010"}]'
>>> # l is a list of 2 dictionaries
>>> l = json.loads(s5)
>>> l[0]
{u'description': u'fdsafsa', u'order': u'1', u'place': u'22 Plainsman Rd, Mississauga, ON, Canada', u'lat': 43.5969175, u'lng': -79.7248744, u'locationDate': u'03/24/2010'}
>>> 
>>> l[1]
{u'description': u'sadfdsa', u'order': u'2', u'place': u'50 Dawnridge Trail, Brampton, ON, Canada', u'lat': 43.7304774, u'lng': -79.8055435, u'locationDate': u'03/26/2010'}
>>>

    谢谢

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