kevinya

使用session方式跟其他程式語言很像，以home page作為範例：
先改/locallibrary/catalog/views.py的index()如下：
如此便在server side加入了session變數

# Create your views here.
from .models import Book, Author, BookInstance, Genre

def index(request):
    """
    View function for home page of site.
    """
    # Generate counts of some of the main objects
    num_books=Book.objects.all().count()
    num_instances=BookInstance.objects.all().count()
    # Available books (status = 'a')
    num_instances_available=BookInstance.objects.filter(status__exact='a').count()
    num_authors=Author.objects.count()  # The 'all()' is implied by default.
    num_book_title_icontain_how = Book.objects.filter(title__icontains = 'how').count()

    #這是利用session來記錄訪客的來訪次數
    # Number of visits to this view, as counted in the session variable.
    num_visits=request.session.get('num_visits', 0)
    request.session['num_visits'] = num_visits+1
    
    # Render the HTML template index.html with the data in the context variable
    return render(
        request,
        #index()最後將會導向到下列這個.html檔案:index.html
        'index.html',
        #並且把剛剛從db取得的物件傳送到index.html
        # context={'num_books':num_books,'num_instances':num_instances,'num_instances_available':num_instances_available,'num_authors':num_authors},
        # context={'num_books':num_books,'num_instances':num_instances,'num_instances_available':num_instances_available,'num_authors':num_authors,'num_book_title_icontain_how':num_book_title_icontain_how},
        
        #把session的num_visits變數也加進去
        context={'num_books':num_books,'num_instances':num_instances,
        'num_instances_available':num_instances_available,'num_authors':num_authors,
        'num_book_title_icontain_how':num_book_title_icontain_how,'num_visits':num_visits},
    )

接著再修改/locallibrary/catalog/templates/index.html，在(block content + endblock)區塊的最後加入下面這行：
讓網頁端去讀取這個訪客變數

<p>You have visited this page {{ num_visits }}{% if num_visits == 1 %} time{% else %} times{% endif %}.</p>

如此一來變可以在catalog的home page看到訪客來訪次數了：

這篇大概先這樣…

參考資料：
Django Tutorial Part 7: Sessions framework
https://developer.mozilla.org/en-US/docs/Learn/Server-side/Django/Sessions