Django中实现可选ForeignKey字段的表单验证指南

from django.db import models

class CourtOrderCategory(models.Model):
    name = models.CharField(max_length=100)
    # ... 其他字段

class Institution(models.Model):
    name = models.CharField(max_length=100)
    # ... 其他字段

class CourtOrder(models.Model):
    sign = models.CharField('Court Order Sign', max_length=50)
    category = models.ForeignKey(CourtOrderCategory, blank=True, null=True, on_delete=models.PROTECT)
    description = models.CharField('Description', blank=True, max_length=50)
    show_in_sidebar = models.BooleanField('Show in Sidebar', default=True)
    institution = models.ForeignKey(Institution, blank=True, null=True, on_delete=models.PROTECT)
    date = models.DateField('Court Order date', blank=True, null=True)
    effect_date = models.DateField('Court Order Date of Effect', blank=True, null=True)
    next_update = models.DateField('Next Update', blank=True, null=True)
    # ... 其他字段

from django import forms
from django.forms import ModelForm
# 假设 CourtOrder, Institution, CourtOrderCategory 已导入

class CourtOrderForm(ModelForm):
    institution = forms.ModelChoiceField(queryset=Institution.objects.filter(category__category__icontains="gericht"))
    category = forms.ModelChoiceField(queryset=CourtOrderCategory.objects.order_by('name'))

    class Meta:
        model = CourtOrder
        fields = (
            'sign',
            'category',
            'description',
            'show_in_sidebar',
            'institution',
            'date',
            'effect_date',
            'next_update',
            # ... 其他字段
        )

from django import forms
from django.forms import ModelForm
# 假设 CourtOrder, Institution, CourtOrderCategory 已导入

class CourtOrderForm(ModelForm):
    # 明确设置 required=False
    institution = forms.ModelChoiceField(queryset=Institution.objects.filter(category__category__icontains="gericht"), required=False)
    category = forms.ModelChoiceField(queryset=CourtOrderCategory.objects.order_by('name'), required=False)

    class Meta:
        model = CourtOrder
        fields = (
            'sign',
            'category',
            'description',
            'show_in_sidebar',
            'institution',
            'date',
            'effect_date',
            'next_update',
            # ... 其他字段
        )

from django.shortcuts import render, HttpResponseRedirect
from .models import Record # 假设 Record 模型存在
# from .forms import CourtOrderForm # 确保导入了修正后的表单

def add_court_order(request, record_pk):
    record = Record.objects.get(pk=record_pk)
    sign_submitted = False

    if request.method == "POST":
        new_courtorder_form = CourtOrderForm(request.POST) # 使用修正后的表单
        if new_courtorder_form.is_valid(): # 检查表单是否有效
            courtorder = new_courtorder_form.save() # 保存数据，此时可选字段可为空
            return HttpResponseRedirect(f'/add_court_order/{record.pk}?courtorder_pk={courtorder.pk}')
        else:
            # 如果表单无效，需要将表单实例传回模板以显示错误信息
            # 此时 courtorder 变量未定义，需要确保模板能处理这种情况
            print(new_courtorder_form.errors) # 打印错误以便调试
            courtorder_instance = new_courtorder_form # 将无效表单传给模板
            # 保持 sign_submitted 为 False 或根据逻辑调整
    else:
        # GET 请求，初始化一个空表单
        courtorder_instance = CourtOrderForm()
        if 'courtorder_pk' in request.GET:
            courtorder_pk = request.GET.get('courtorder_pk')
            # 这里的逻辑似乎有误，应该获取 CourtOrder 实例而不是 Record
            # 假设这里是为了显示已创建的 CourtOrder 详情
            try:
                courtorder_instance = CourtOrder.objects.get(pk=courtorder_pk)
                sign_submitted = True
            except CourtOrder.DoesNotExist:
                pass # 处理找不到 CourtOrder 的情况

    return render(request, 'add_court_order.html', {
        'courtorder': courtorder_instance, # 确保传递一个有效的表单或模型实例
        'record': record,
        'sign_submitted': sign_submitted
    })