Question

I’m new to django. I’m reading blog tutorial.From blog tutorial I’m unable to understand following part. Can any one explain me? I shall be very thankful. thanks

from django.forms import ModelForm

class CommentForm(ModelForm):
    class Meta:
        model = Comment
        exclude = ["post"]

    def add_comment(request, pk):
        """Add a new comment."""
        p = request.POST

        if p.has_key("body") and p["body"]:
            author = "Anonymous"
            if p["author"]: author = p["author"]

            comment = Comment(post=Post.objects.get(pk=pk))
            cf = CommentForm(p, instance=comment)
            cf.fields["author"].required = False

            comment = cf.save(commit=False)
            comment.author = author
            comment.save()
        return HttpResponseRedirect(reverse("dbe.blog.views.post", args=[pk]))

Answer 1

class CommentForm(ModelForm):
    class Meta:
        model = Comment
        exclude = ["post"]

    def add_comment(request, pk):
        """Add a new comment."""
        p = request.POST 

        # if POST has key "body" and p["body"] evalutes to True
        if p.has_key("body") and p["body"]: #


            author = "Anonymous"
            # if the value for key "author" in p evaluates to True
            # assign its value to the author variable.
            if p["author"]: author = p["author"]

            # create comment pointing to Post id: pk passed into this function
            comment = Comment(post=Post.objects.get(pk=pk))

            # generate modelform to edit comment created above
            cf = CommentForm(p, instance=comment)
            cf.fields["author"].required = False

            # use commit=False to return an unsaved comment instance
            # presumably to add in the author when one hasn't been specified.
            comment = cf.save(commit=False)
            comment.author = author
            comment.save()
        return HttpResponseRedirect(reverse("dbe.blog.views.post", args=[pk]))

The author is trying to assign a default value to the author field if one isn’t passed in.

You could probably shorten the code quite a bit by making a mutable copy of the POST QueryDict to solve the same problem.

Does this make more sense to you?

class CommentForm(ModelForm):
    class Meta:
        model = Comment
        exclude = ["post"]

    def add_comment(request, pk):
        """Add a new comment."""
        p = request.POST.copy()

        if p.has_key("body") and p["body"]:
            if not p["author"]:
                p["author"] = 'Anonymous'

            comment = Comment(post=Post.objects.get(pk=pk))
            cf = CommentForm(p, instance=comment)
            cf.save()

        return HttpResponseRedirect(reverse("dbe.blog.views.post", args=[pk]))