Export data as excel from class based view-CodePudding

I have class based view and when request is post, self.readdb() will give dictionary result to self.db_result variable which will be populated as html table. This is working fine.

I need to export this table as excel.

My view.py

  class Download(View):
    def __init__(self, logger=None, **kwargs):
        self.logger = logging.getLogger(__name__)
        self.db_result = []

  def post(self, request):
    if request.method == 'POST':
        form = DownloadForm(request.POST, request.FILES)
        if form.is_valid():  
            self.db_result = self.readdb() 
            if self.db_result != False:
                return render(request,'download.html',{'present': self.db_result[0]})

        <table >
            <caption>Present in DB</caption>
            <tbody>
                {% for key, value in present.items %}
                    <tr>
                        <td> {{ key }} </td> <td> {{ value }} </td>
                    </tr>
                {% endfor %}
            </tbody>
            <a href="{% url 'export_excel' %}">Download excel file</a>
        </table>
    {% endif %}

I tried following which is generating excel file when click but it doesn't have any data. print(self.db_result) in get function is printing []. Looks like result from "post" is not available in "get".

    def get(self, request):
       if request.method == 'GET':    
            if request.path_info == '/export/excel':
                print(self.db_result)
                response = self.export_users_xls()
                return response

    def export_users_xls(self):
        response = HttpResponse(content_type='text/csv')
        response['Content-Disposition'] = 'attachement; filename="report.csv"'
        print(self.db_result)
        writer = csv.writer(response)
        writer.writerow(['Command', 'XML data'])

        return response

How can I access self.db_result from "post" function in "get" so that I can generate excel file. If I'm doing wrong, please guide me to correct steps. I'm not using Models. self.db_result from post has the required result which should be populated as excel.

CodePudding user response：

You can't as such. The GET action and the POST actions are separate types of request - one loads a page and possibly sends name/value pairs from a form via the URL, and the other posts the pairs behind the scenes. A variable created in one function isn't immediately available in another, because they are run as different requests/page loads.

If you need to refer to a previous variable you can store it as a session variable for later (see docs for more)

eg in your post()

    if form.is_valid():  
        self.db_result = self.readdb() 
        request.session['db_result'] = self.db_result

and then later, in your get()

   #use session.get() to return None if variable has not been set.
   self.db_result = request.session.get('db_result')