django輸出空csv

Question

我使用django，我試圖將CSV_data列表導出到csv文件中。下面是我的csv.py：

#coding=utf-8 
from django.http import HttpResponse 
from django.template import loader, Context 
from demo.views import CSV_data 


def output(request, filename): 
    response = HttpResponse(mimetype='text/csv') 
    response['Content-Disposition'] = 'attachment; filename=%s.csv' % filename 

    t = loader.get_template('csv.txt') 
    c = Context({ 
     'data': CSV_data, 
    }) 
    response.write(t.render(c)) 
    return response 

CSV_data是views.py一個變量，我試圖打印模板，該值是確定的。

[(u'2012-06-01', [0, 0, 0]), ('2012-06-08', [0, 0, 0]), ('2012-06-15', [0, 0, 0]), ('2012-06-22', [0, 0, 0]), ('2012-06-29', [0, 0, 0]), ('2012-07-06', [0, 0, 0]), ('2012-07-13', [0, 0, 0]), ('2012-07-20', [0, 0, 0]), ('2012-07-27', [0, 0, 0]), ('2012-08-03', [131, 164, 79.88]), ('2012-08-10', [110, 198, 55.56]), ('2012-08-17', [112, 197, 56.85]), ('2012-08-24', [147, 283, 51.94]), ('2012-08-31', [0, 306, 0.0]), ('2012-09-07', [418, 418, 100.0]), ('2012-09-14', [342, 342, 100.0]), ('2012-09-21', [732, 732, 100.0]), ('2012-09-28', [689, 689, 100.0]), ('2012-10-05', [775, 775, 100.0]), ('2012-10-12', [469, 469, 100.0]), ('2012-10-19', [477, 477, 100.0]), ('2012-10-26', [897, 897, 100.0]), ('2012-11-02', [216, 216, 100.0]), ('2012-11-09', [1046, 1046, 100.0]), ('2012-11-16', [840, 840, 100.0]), ('2012-11-23', [948, 948, 100.0])] 

但是，生成的csv始終爲空。

我試圖CSV_data定義添加到csv.py文件，像這樣：

#coding=utf-8 
from django.http import HttpResponse 
from django.template import loader, Context 

CSV_data = [(u'2012-06-01', [0, 0, 0]), ('2012-06-08', [0, 0, 0]), ('2012-06-15', [0, 0, 0]), ('2012-06-22', [0, 0, 0]), ('2012-06-29', [0, 0, 0]), ('2012-07-06', [0, 0, 0]), ('2012-07-13', [0, 0, 0]), ('2012-07-20', [0, 0, 0]), ('2012-07-27', [0, 0, 0]), ('2012-08-03', [131, 164, 79.88]), ('2012-08-10', [110, 198, 55.56]), ('2012-08-17', [112, 197, 56.85]), ('2012-08-24', [147, 283, 51.94]), ('2012-08-31', [0, 306, 0.0]), ('2012-09-07', [418, 418, 100.0]), ('2012-09-14', [342, 342, 100.0]), ('2012-09-21', [732, 732, 100.0]), ('2012-09-28', [689, 689, 100.0]), ('2012-10-05', [775, 775, 100.0]), ('2012-10-12', [469, 469, 100.0]), ('2012-10-19', [477, 477, 100.0]), ('2012-10-26', [897, 897, 100.0]), ('2012-11-02', [216, 216, 100.0]), ('2012-11-09', [1046, 1046, 100.0]), ('2012-11-16', [840, 840, 100.0]), ('2012-11-23', [948, 948, 100.0])] 

def output(request, filename): 
    response = HttpResponse(mimetype='text/csv') 
    response['Content-Disposition'] = 'attachment; filename=%s.csv' % filename 

    t = loader.get_template('csv.txt') 
    c = Context({ 
     'data': CSV_data, 
    }) 
    response.write(t.render(c)) 
    return response 

然後輸出CSV是不是空的。所以我猜想從views.py導入CSV_data時會出現問題。

問題是我測試過，視圖中的CSV_data值是正確的。那麼會出現什麼問題呢？

** * ** * ** * ** * ** * *UPDATE* ** * ** * ** * ** * ** *：

在views.py原來的代碼是這樣的：

CSV_data = [] 
def part_usage_result(request): 
    ...(details omit) 
    usageDictWeek = helper.getResultByWeek(modelName, spareCode, start, end) #returns a list 
    CSV_data=usageDictWeek 

我更改爲：

CSV_data = [] 
def part_usage_result(request): 
    ...(details omit) 
    usageDictWeek = helper.getResultByWeek(modelName, spareCode, start, end) #returns a list 
    for each in usageDictWeek: 
     CSV_data.append(each) 

現在CSV的內容是正確的。 仍然不知道爲什麼會這樣

Answer 1

由於您沒有提供細節helper.getResultByWeek，它是怎麼叫，我想它返回一個全局變量與列表值，並且這個變量在兩者之間的某處被修改。

CSV_data = usageDictWeek 

不復制列表，但創建另一個引用到現有的。當稍後原始usageDictWeek被修改時，CSV_data也被修改。

當你這樣做，而不是

CSV_data[:] = usageDictWeek 

被創建並分配給CSV_data的usageDictWeek新副本。

Answer 2

關鍵字try content_type，而不是MIME類型