根据先前选择的元素过滤Django表单选择元素

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中解决这个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:

图片示例

<!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>

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选择了Brand1,则第二个选择将仅使用Brand为Brand1的汽车进行过滤,这只是"Model1_B1".

OBS.我看过很多带有forms.ModelChoiceField的解决方案,但只能用于编辑,因为用户不会改变品牌.

Answer 1

经过几个小时的研究,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的或更优雅的,但是有效.(要下载完整的Django项目,请单击此repo => 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

目标是在车队登记汽车.将记录的唯一字段:Car(外键)和描述.在表单上,​​将有一个选择元素的品牌,只能作为过滤汽车的组合框的帮手.

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是一个用于注册汽车的表单,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})

该视图几乎是自动解释的.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 %}

该模板只是呈现表单并加载脚本JS.没有其他的.

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/