Django - show loading message during long processing

Question

How can I show a please wait loading message from a django view?

I have a Django view that takes significant time to perform calculations on a large dataset

Answer 1

Iterating HttpResponse

https://stackoverflow.com/a/1371061/198062

Edit:

I found an example to sending big files with django: http://djangosnippets.org/snippets/365/ Then I look at FileWrapper class(django.core.servers.basehttp):

class FileWrapper(object):
    """Wrapper to convert file-like objects to iterables"""

    def __init__(self, filelike, blksize=8192):
        self.filelike = filelike
        self.blksize = blksize
        if hasattr(filelike,'close'):
            self.close = filelike.close

    def __getitem__(self,key):
        data = self.filelike.read(self.blksize)
        if data:
            return data
        raise IndexError

    def __iter__(self):
        return self

    def next(self):
        data = self.filelike.read(self.blksize)
        if data:
            return data
        raise StopIteration

I think we can make a iterable class like this

class FlushContent(object):
    def __init__(self):
        # some initialization code

    def __getitem__(self,key):
        # send a part of html

    def __iter__(self):
        return self

    def next(self):
        # do some work
        # return some html code
        if finished:
            raise StopIteration

then in views.py

def long_work(request):
    flushcontent = FlushContent()
    return HttpResponse(flushcontent)

Edit:

Example code, still not working:

class FlushContent(object):
    def __init__(self):
        self.stop_index=2
        self.index=0

    def __getitem__(self,key):
        pass

    def __iter__(self):
        return self

    def next(self):
        if self.index==0:
            html="loading"
        elif self.index==1:
            import time
            time.sleep(5)
            html="finished loading"

        self.index+=1

        if self.index>self.stop_index:
            raise StopIteration

        return html