Question

我正在从一些模型数据创建一个列表，但我没有正确地做它，它可以正常工作，但是当我刷新broswer reportResults中的页面时，只是添加了。我希望它会在请求之间收集垃圾，但显然我做错了什么，有什么想法吗？

谢谢，伊万

reportResults = []   #the list that doesn't get collected
def addReportResult(fix,description):  
    fix.description = description
    reportResults.append(fix)

def unitHistory(request,unitid, syear, smonth, sday, shour, fyear, fmonth, fday, fhour, type=None):
   waypoints = Fixes.objects.filter(name=(unitid))
    waypoints = waypoints.filter(gpstime__range=(awareStartTime, awareEndTime)).order_by('gpstime')[:1000]
    if waypoints:
        for index in range(len(waypoints)): 
...do stuff here selecting some waypoints and generating "description" text
                    addReportResult(waypointsindex,description) ##append the list with this, adding a text description

    return render_to_response('unitHistory.html', {'fixes': reportResults})

Answer 1

每次重复使用相同的列表，要修复它，您需要重新构建代码以在每个请求上创建新列表。这可以通过多种方式完成，这是一种方式：

def addReportResult(reportResults, fix,description):  
    fix.description = description
    reportResults.append(fix)

def unitHistory(request,unitid, syear, smonth, sday, shour, fyear, fmonth, fday, fhour, type=None):

    reportResults = [] # Here we create our local list that is recreated each request.

    waypoints = Fixes.objects.filter(name=(unitid))
    waypoints = waypoints.filter(gpstime__range=(awareStartTime, awareEndTime)).order_by('gpstime')[:1000]
    if waypoints:
        for index in range(len(waypoints)):
            # Do processing
            addReportResult(reportResults, waypointsindex, description)
            # We pass the list to the function so it can use it.

return render_to_response('unitHistory.html', {'fixes': reportResults})

如果addReportResult保持较小，您还可以通过完全取消对description的调用并在同一位置执行addReportResult来内联waypointsindex.description = description属性集。

Answer 2

为了让您了解请求的生命周期，mod_wsgi将保持一个进程为多个请求提供服务。该过程每隔一段时间就会被回收，但它绝对不会像您所假设的那样受到单个请求的约束。

这意味着您需要一个本地列表。我建议直接在线移动addReportResult函数内容，但如果它需要可重用或函数太长，那不是一个好主意。相反，我会让该功能返回该项目，您可以在本地收集结果。

def create_report(fix, description): # I've changed the name to snake_casing
    fix.description = description
    return fix

def unit_history(request,unitid, syear, smonth, sday, shour, fyear, fmonth, fday, fhour, type=None):
    reports = []
    waypoints = Fixes.objects.filter(name=(unitid))
    waypoints = waypoints.filter(gpstime__range=(awareStartTime, awareEndTime)).order_by('gpstime')[:1000]
    if waypoints:
        for index in range(len(waypoints)): 
            report = create_report(waypointsindex, description)
            reports.append(report)
    return render_to_response('unitHistory.html', {'fixes': reportResults})

django列表在视图之间没有被破坏

2 个答案: