Fields generated by inlineformset_factory disappears when validation fails

I have a simple Book Author relationship

class Author(models.Model):
    first_name = models.CharField(max_length=125)
    last_name = models.CharField(max_length=125)
    created = models.DateTimeField(auto_开发者_JAVA百科now_add=True)
    updated = models.DateTimeField(auto_now=True)

class Book(models.Model):
    title = models.CharField(max_length=225)
    author = models.ForeignKey(Author)

class AuthorForm(forms.ModelForm):
    class Meta:
        model = Author

class BookForm(forms.ModelForm):
    class Meta:
        model = Book

This is what I have in my view

def addbook(request):

    BookFormSet = inlineformset_factory(models.Author, models.Book, extra=1)

    if request.method == 'GET':
        author = models.AuthorForm()
        books = BookFormSet()
    else:
        author = models.AuthorForm(request.POST)
        if author.is_valid():
            books = BookFormSet(request.POST)
            if books.is_valid():
                print(books)

    return render_to_response('bookadd.html', locals(), context_instance = RequestContext(request))

My template looks like this

<form action="/books/add_new" method="post">
      {% csrf_token %}
      <table>
        <tr>
          <td>First name: </td>
          <td>{{ author.first_name }}</td>
          <td>{{author.first_name.errors}}</td>
        </tr>
        <tr>
          <td>Last name</td>
          <td>{{ author.last_name }}</td>
          <td>{{author.last_name.errors}}</td>
        </tr>
      </table>
      {{ books.management_form }}
      {{ books.as_table }}
      <br/>
      <input type="submit" value="Submit" />
    </form>

If I leave the title field blank and hit enter, on post back the book title field disappears, and I cannot figure out what to do about it. I want the field to be there with any data that was entered by the user.

You might try

    author = models.AuthorForm(request.POST)
    books = BookFormSet(request.POST)
    if author.is_valid():

instead of

    author = models.AuthorForm(request.POST)
    if author.is_valid():
        books = BookFormSet(request.POST)