Question

让我们考虑以下模型

models.py

Class Brand(models.Model):
    company_name = models.CharField(max_length=100)


class CarModel(models.Model):
    brand = models.ForeignKey(Brand)
    name = models.CharField(max_length=100)


Class FleetCars(models.Model):
    model_car = models.Foreignkey(CarModel)

在django中解决此问题的最佳方法是什么？假设一个表单（用于FleetCars中的插入）由两个选择元素组成，如下所示：

Image example

＆＃13;

<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>

<br />Brand:
<select>
   <option value="Brand1">Brand1</option>
   <option value="Brand2">Brand2</option>
</select>
<br />
<br />Model:
<select>
   <option value="Model1_B1">Model1_B1</option>
   <option value="Model1_B2">Model1_B2</option>
</select>

</body>
</html>

＆＃13;

在这种情况下，我希望第二个选项中的选项取决于在第一个选择中选择的值，例如，如果用户在第一个选择中为Brand选择Brand1，则第二个选择将仅使用其中的汽车进行过滤品牌是Brand1，这只是＆＃34; Model1_B1＆＃34;。

OB的。我看过很多带有forms.ModelChoiceField的解决方案，但只适用于编辑，因为用户不会改变品牌。

Answer 1

经过数小时和数小时的研究，没有成功，我决定尝试自己解决。我找到的解决方案可能不是最好或更优雅，但是正在发挥作用。（要下载完整的Django项目，请单击此repo =＆gt; https://github.com/Sidon/djfkf/。）

models.py

from django.db import models

class Brand(models.Model):
    company_name = models.CharField(max_length=100)

    def __str__(self):
        return self.company_name


class Car(models.Model):
    brand = models.ForeignKey(Brand)
    name = models.CharField(max_length=100)

    def brand_name(self):
        return self.brand.company_name

    def __str__(self):
        return self.name


class Fleet(models.Model):
    car = models.ForeignKey(Car)
    description = models.CharField(max_length=100)

    def car_name(self):
        return self.car.name

    def brand(self):
        return self.car.brand.company_name

    def __str__(self):
        return self.description

目标是在车队登记车辆。将记录的唯一字段：Car（外键）和描述。在表单上，将有一个品牌选择元素，仅作为过滤汽车组合框的助手。

forms.py

import json
from django import forms
from .models import *

class RegCarForm(forms.ModelForm):

    dcars = {}
    list_cars = []
    for car in Car.objects.all():
        if car.brand.company_name in dcars:
            dcars[car.brand.company_name].append(car.name)
        else:
            dcars[car.brand.company_name] = [car.name]
        list_cars.append((car.name,car.name))

    brands = [str(brand) for brand in Brand.objects.all()]

    brand_select = forms.ChoiceField(choices=([(brand, brand) for brand in brands]))
    car_select = forms.ChoiceField(choices=(list_cars))

    brands = json.dumps(brands)
    cars = json.dumps(dcars)

    class Meta:
        model = Fleet
        fields = ('brand_select', 'car_select', 'description',)

RegCarForm是注册汽车的表格，有三个字段：brand_select，car_select和description。另外，我定义了两个JSON属性：1）一个字典，其键是品牌（字符串），值是各自汽车的列表，以及2）代表品牌的字符串列表。这两个属性将作为JS函数的助手。

views.py

from django.shortcuts import render
from .forms import RegCarForm
from .models import *

def regcar(request):
    if request.method == 'POST':
        car_form = RegCarForm(data=request.POST)

        if car_form.is_valid():
            cdata = car_form.cleaned_data.get
            car_selected = Car.objects.filter(name=cdata('car_select'))
            reg1 = Fleet(car_id=car_selected[0].id, description=cdata('description'))
            reg1.save()
        else:
            print ('Invalid')

    else:
        car_form = RegCarForm()
    return render(request, 'core/regcar.html', {'car_form': car_form})

该视图实际上是自动解释的。将Form分配给car_form变量，渲染模板core / regcar.html，然后在Post之后，对表单进行验证并保存数据。

regcar.html（模板django）

{% extends "base.html" %}

{% block head %}
{% endblock %}

{% block content %}
    <h1>Registering cars on the fleet. <br />(Populate one drop down based on selection in another)</h1>
    <p>Change the contents of drop down Car based on the selection in dropdown Brand, using Django-forms + Javascritp</p>
    <div class="select-style">
        <form action="." method="post">
            {% csrf_token %}
            {{ car_form.as_p }}
            <p><input type="submit" value="Register a car"></p>
        </form>
    </div>
{% endblock %}

{% block js %}
    {% include "js1.html" %}
{% endblock %}

模板只是呈现表单并加载脚本JS。没别了。

最后，js脚本，这使得努力工作。

{% block js %}
    <script language="javascript">
        $('#id_brand_select').change(function() {populateCar(this)});
        $('#id_description').addClass('descriptions');
        cars = {{ car_form.cars | safe }}
        brands = {{ car_form.brands | safe}};
        populateBrand();
        $("#id_car_select").empty();
        $("#id_car_select").append('<option value="" disabled selected>First select a brand</option>');
        function populateBrand() {
            $('#id_brand_select').empty();
            $("#id_brand_select").append('<option value="" disabled selected>Select your option</option>');
            $.each(brands, function(v) {
                $('#id_brand_select')
                    .append($("<option></option>")
                    .attr("value", brands[v])
                    .text(brands[v]));
            });
        }

        function populateCar(event) {
            brand = $("#id_brand_select option:selected").text();
            $("#id_car_select").empty();
            $("#id_car_select").append('<option value="" disabled selected>Select your option</option>');
            for (let [b, bcars] of Object.entries(cars)) {
                if (b == brand) {
                    //alert(b);
                    for (car in bcars) {
                        $('#id_car_select')
                            .append($("<option></option>")
                                .attr("value", bcars[car])
                                .text(bcars[car]));
                    }
                }
            }
        }
    </script>
{% endblock %}

加载文档时，此脚本会将brand_select的更改事件（用于选择品牌的组合）分配给函数poplulateCar，将表单的JASON属性（汽车和品牌）分配给JS变量并调用populateBrand函数。

链接：

Django的完整项目：
https://github.com/Sidon/djfkf/

根据先前选择的元素过滤Django表单选择元素

1 个答案:

链接：