在Django 1.6和Python 2.7中实现chartit：TypeError：'NoneType'没有属性__getitem__ - 需要更多信息

Question

我在参考一个StackOverflow的问题，链接是 在Django 1.6中用Python 2.7实现chartit - 类型错误：'NoneType'没有属性 __getitem__

我没有足够的积分去评论那个人的帖子，也无法联系他们，但他们提到：

“我已经解决了这个问题。问题确实出在这一行 hco['chart']['renderTo'] = render_to。我必须修复一些数据一致性的问题，现在它可以正常工作了。”

这些数据一致性问题是什么呢？这肯定和Django的新版本有关。

我在按照这个教程 http://chartit.shutupandship.com/docs/ 学习。

我遇到了同样的错误：'NoneType'对象没有属性 'getitem'

models.py

class MonthlyWeatherByCity(models.Model):
    month = models.IntegerField()
    boston_temp = models.DecimalField(max_digits=5, decimal_places=1)
    houston_temp = models.DecimalField(max_digits=5, decimal_places=1)

    def __unicode__(self):
        return unicode(self.month)

views.py

def weather_chart_view(request):
    #Step 1: Create a DataPool with the data we want to retrieve.
    context = RequestContext(request)
    weatherdata = \
        DataPool(
           series=
            [{'options': {
               'source': MonthlyWeatherByCity.objects.all()},
              'terms': [
                'month',
                'houston_temp',
                'boston_temp']}
             ])

    #Step 2: Create the Chart object
    chart_list = Chart(
            datasource = weatherdata,
            series_options =
              [{'options':{
                  'type': 'line',
                  'stacking': False},
                'terms':{
                  'month': [
                    'boston_temp',
                    'houston_temp']
                  }}],
            chart_options =
              {'title': {
                   'text': 'Weather Data of Boston and Houston'},
               'xAxis': {
                    'title': {
                       'text': 'Month number'}}})

index.html

<div id='container'> {{ weatherchart|load_charts:"container" }} </div>

<script type="text/javascript" src="/static/js/jquery-1.11.0.js"></script>
<script type="text/javascript" src="/static/js/highcharts.js"></script>

调试页面

/home/nimbus/.virtualenvs/nimbus_portal/lib/python2.7/site-packages/chartit/templatetags/chartit.py in load_charts
                hco['chart']['renderTo'] = render_to ...
▼ Local vars
Variable    Value
**chart_list    
[]**

我附上了chartit.py的代码供你查看。我不确定需要修复/更改哪些数据一致性的问题。

chartit.py

from itertools import izip_longest
from django import template
from django.utils import simplejson
from django.utils.safestring import mark_safe
from django.conf import settings
import posixpath

from ..charts import Chart, PivotChart

try:
    CHARTIT_JS_REL_PATH = settings.CHARTIT_JS_REL_PATH
    if CHARTIT_JS_REL_PATH[0] == '/':
        CHARTIT_JS_REL_PATH = CHARTIT_JS_REL_PATH[1:]
    CHART_LOADER_URL = posixpath.join(settings.STATIC_URL, 
                                      CHARTIT_JS_REL_PATH,
                                      'chartloader.js')
except AttributeError:
    CHARTIT_JS_REL_PATH = 'chartit/js/'
    CHART_LOADER_URL = posixpath.join(settings.STATIC_URL, 
                                      CHARTIT_JS_REL_PATH,
                                      'chartloader.js')

register = template.Library()

@register.filter
def load_charts(chart_list=None, render_to=''):
    """Loads the ``Chart``/``PivotChart`` objects in the ``chart_list`` to the 
    HTML elements with id's specified in ``render_to``. 

    :Arguments:

    - **chart_list** - a list of Chart/PivotChart objects. If there is just a 
      single element, the Chart/PivotChart object can be passed directly 
      instead of a list with a single element.

    - **render_to** - a comma separated string of HTML element id's where the 
      charts needs to be rendered to. If the element id of a specific chart 
      is already defined during the chart creation, the ``render_to`` for that 
      specific chart can be an empty string or a space.

      For example, ``render_to = 'container1, , container3'`` renders three 
      charts to three locations in the HTML page. The first one will be 
      rendered in the HTML element with id ``container1``, the second 
      one to it's default location that was specified in ``chart_options`` 
      when the Chart/PivotChart object was created, and the third one in the
      element with id ``container3``.

    :returns:

    - a JSON array of the HighCharts Chart options. Also returns a link
      to the ``chartloader.js`` javascript file to be embedded in the webpage. 
      The ``chartloader.js`` has a jQuery script that renders a HighChart for 
      each of the options in the JSON array"""

    embed_script = (
      '<script type="text/javascript">\n'
      'var _chartit_hco_array = %s;\n</script>\n'
      '<script src="%s" type="text/javascript">\n</script>')

    if chart_list is not None:
        if isinstance(chart_list, (Chart, PivotChart)):
            chart_list = [chart_list]
        chart_list = [c.hcoptions for c in chart_list]
        render_to_list = [s.strip() for s in render_to.split(',')]
        for hco, render_to in izip_longest(chart_list, render_to_list):
            if render_to:
                hco['chart']['renderTo'] = render_to
        embed_script = (embed_script % (simplejson.dumps(chart_list, 
                                                         use_decimal=True),
                                        CHART_LOADER_URL))
    else:
        embed_script = embed_script %((), CHART_LOADER_URL)
    return mark_safe(embed_script)

Answer 1

名字 'weatherchart' 没有和任何图表对象关联起来。

在视图函数的最后，你应该有：

return render_to_response(<template>, {'<chart_name>': <chart_object>})

在模板中（这里是 index.html）：

{{ <chart_name>|load_charts:"container" }}