django 添加动态表格的方法

传统方法（基于方法的视图）：http://stellarchariot.com/blog/2011/02/dynamically-add-form-to-formset-using-javascript-and-django/

概要：

     服务器端，使用了formset  ， 文档在这里：https://docs.djangoproject.com/en/dev/topics/forms/formsets/

     客户端，使用脚本动态添加内容。

class based view ,参考这里：http://kevindias.com/writing/django-class-based-views-multiple-inline-formsets/

总结：

      重写了get/post方法。

      要点： 

         1. form里面做关联：

# forms.py
from django.forms import ModelForm
from django.forms.models import inlineformset_factory

from .models import Recipe, Ingredient, Instruction


class RecipeForm(ModelForm):
    class Meta:
        model = Recipe


IngredientFormSet = inlineformset_factory(Recipe, Ingredient)
InstructionFormSet = inlineformset_factory(Recipe, Instruction)

　　2. 重写post/get方法，并在里面对子表初始化，注意get里面构造时无参，post里有参。

ingredient_form = IngredientFormSet()  vs  ingredient_form = IngredientFormSet(self.request.POST)

class RecipeCreateView(CreateView):
    template_name = 'recipe_add.html'
    model = Recipe
    form_class = RecipeForm
    success_url = 'success/'

    def get(self, request, *args, **kwargs):
        """
        Handles GET requests and instantiates blank versions of the form
        and its inline formsets.
        """
        self.object = None
        form_class = self.get_form_class()
        form = self.get_form(form_class)
        ingredient_form = IngredientFormSet()
        instruction_form = InstructionFormSet()
        return self.render_to_response(
            self.get_context_data(form=form,
                                  ingredient_form=ingredient_form,
                                  instruction_form=instruction_form))

    def post(self, request, *args, **kwargs):
        """
        Handles POST requests, instantiating a form instance and its inline
        formsets with the passed POST variables and then checking them for
        validity.
        """
        self.object = None
        form_class = self.get_form_class()
        form = self.get_form(form_class)
        ingredient_form = IngredientFormSet(self.request.POST)
        instruction_form = InstructionFormSet(self.request.POST)
        if (form.is_valid() and ingredient_form.is_valid() and
            instruction_form.is_valid()):
            return self.form_valid(form, ingredient_form, instruction_form)
        else:
            return self.form_invalid(form, ingredient_form, instruction_form)

　　3. 保存时做关联：

ingredient_form.instance = self.object

   def form_valid(self, form, ingredient_form, instruction_form):
        """
        Called if all forms are valid. Creates a Recipe instance along with
        associated Ingredients and Instructions and then redirects to a
        success page.
        """
        self.object = form.save()
        ingredient_form.instance = self.object
        ingredient_form.save()
        instruction_form.instance = self.object
        instruction_form.save()
        return HttpResponseRedirect(self.get_success_url())

　　4. 模板注意包含两个隐藏域：

                {{ ingredient_form.management_form }}
                {{ ingredient_form.non_form_errors }}

　　

 3. 自己写了个demo，完整代码看这里： https://github.com/TommyU/dynamic_form/