使用新的“虚拟"保存基于类的视图表单集项目.柱子

问题描述

我在表单中有一个表格，由表单集生成.

I have a table inside a form, generated by a formset.

在这种情况下，我的问题是在其中一项被修改后保存所有项目，添加一个新的虚拟"列作为其他两项的总和(仅在显示表格时生成，不保存).我尝试了不同的方法，但没有一种方法有效.

In this case, my problem is to save all the items after one of them is modified, adding a new "virtual" column as the sum of other two (that is only generated when displaying the table, not saved). I tried different ways, but no one is working.

问题:

• 这个 save 根本不起作用.它只有一种形式时有效，但不适用于形式集
• 我尝试将 amount 列生成为 box_one 和 box_two 的 Sum ，但没有成功.我也尝试过以这种方式生成表单，但这不起作用:

models.py

views.py

urls.py

item_list.html

... <div> <form action="" method="post"></form> <table> {% csrf_token %} {{ formset.management_form }} {% for form in formset %} <thead> <tr> {% if forloop.first %} <th>{{ form.code.label_tag }} </th> <th>{{ form.description.label_tag }} </th> <th> <label>Amount:</label> </th> <th>{{ form.box_one.label_tag }} </th> <th>{{ form.box_two.label_tag }} </th> {% endif %} </tr> </thead> <tbody> <tr> <td>{{ form.code }}</td> <td>{{ form.description }}</td> <td>{{ form.amount }}</td> <td>{{ form.box_one }}</td> <td>{{ form.box_two }}</td> </tr> </tbody> {% endfor %} <input type="submit" value="Update" /> </table> </form> </div> ...

推荐答案

用虚拟列注释查询

Sum 是 聚合表达式 而不是在这种情况下您希望注释此查询的方式.相反，您应该使用 F 表达式 将两个数字字段的值相加

Annotatingquerywithvirtualcolumn

Sum is an aggregate expression and is not how you want to be annotating this query in this case. Instead, you should use an F exrepssion to add the value of two numeric fields

qs.annotate(virtual_col=F('field_one') + F('field_two'))

所以你更正的查询集将是

So your corrected queryset would be

Item.objects.order_by('code__name').annotate(amount=F('box_one') + F('box_two'))

如果打算将该属性仅用于行级"操作，则 cezar 提供的答案非常有用.但是，如果您打算根据amount进行查询，则需要对查询进行注释.

The answer provided by cezar works great if intend to use the property only for 'row-level' operations. However, if you intend to make a query based on amount, you need to annotate the query.

您没有在视图类中提供 post 方法.您需要自己提供一个，因为您没有从为您提供一个的通用视图继承.请参阅 使用基于类的视图处理表单.您还应该考虑从处理表单的通用视图继承.例如 ListView 没有实现 post 方法，但 FormView 实现了.

You have not provided a post method in your view class. You'll need to provide one yourself since you're not inheriting from a generic view that provides one for you. See the docs on Handling forms with class-based views. You should also consider inheriting from a generic view that handles forms. For example ListView does not implement a post method, but FormView does.

请注意，您的模板也不会呈现表单错误.由于您正在手动呈现表单集，因此您应该考虑添加字段错误(例如 {{ form.field.errors}})，以便在 HTML 中显示验证问题.请参阅关于手动渲染字段的文档.

Note that your template is also not rendering form errors. Since you're rendering the formset manually, you should consider adding the field errors (e.g. {{ form.field.errors}}) so problems with validation will be presented in the HTML. See the docs on rendering fields manually.

此外，您可以在 post 方法中记录/打印错误.例如:

Additionally, you can log/print the errors in your post method. For example:

def post(self, request, *args, **kwargs):
    formset = MyFormSet(request.POST)
    if formset.is_valid():
        formset.save()
        return SomeResponse
    else:
        print(formset.errors)
        return super().post(request, *args, **kwargs)

如果表单未通过验证，您应该会在控制台/日志中看到错误.

Then if the form does not validate you should see the errors in your console/logs.

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