如何限制表单集中的字段选择？

Question

我在限制表单集中的可选选项时遇到问题。我有以下模型：员工、部门、项目、项目类型、成员资格和角色。员工可以在表单集中添加/删除他们为给定部门项目所扮演的角色，表单应将可选项目限制为仅属于员工所属部门的项目。

型号：

class Department(models.Model):
    name = models.CharField(max_length=20)
    def __unicode__(self):
    return self.name

class Employee(models.Model):
    fname = models.CharField(max_length=15)
    department = models.ForeignKey(Department)
    def __unicode__(self):
        return self.fname

class Projecttype(models.Model):
    name = models.CharField(max_length=20)
    def __unicode__(self):
        return self.name

class Project(models.Model):
    projecttype = models.ForeignKey(Projecttype)
    department = models.ForeignKey(Department)
    members = models.ManyToManyField(Employee, through='Membership')
    def __unicode__(self):
       return "%s > %s" % (self.department, self.projecttype)

class Role(models.Model):
    name = models.CharField(max_length=20)
    def __unicode__(self):
       return self.name

class Membership(models.Model):
    project = models.ForeignKey(Project, null=True)
    department = models.ForeignKey(Department)
    employee = models.ForeignKey(Employee)
    role = models.ManyToManyField(Role, blank=True, null=True)
    class Meta:
        unique_together = (("project", "employee",),)

查看：

def employee_edit(request, employee_id):
    i = get_object_or_404(Employee, pk=employee_id)
    MembershipFormSet = modelformset_factory(Membership, exclude=('department', 'employee'),)
    f = MembershipFormSet(queryset=Membership.objects.filter(employee=i),)
    return render_to_response('gcs/edit.html', {'item': i, 'formset': f, }, context_instance=RequestContext(request))

目前，欧盟可以为任何部门的项目选择一个角色。它的行为是这样的：

项目选项：

Projects.objects.all()

我想通过以下方式限制项目：LIMIT PROJECT CHOCIES TO：

Projects.objects.filter(department=i.department)

Answer 1

这个Stack Overflow question 非常相似。我喜欢马修回答的方法，您可以在一个可以通过闭包访问员工的函数中动态构建表单。在你的情况下，你想要这样的东西：

from django.http import HttpResponseRedirect

def make_membership_form(employee):
    """
    Returns a Membership form for the given employee, 
    restricting the Project choices to those in the 
    employee's department. 
    """
    class MembershipForm(forms.ModelForm):
        project = forms.ModelChoiceField(queryset=Projects.objects.filter(department=employee.department))
        class Meta:
            model = Membership
            excludes = ('department', 'employee',)
    return MembershipForm

def employee_edit(request, employee_id):
    employee = get_object_or_404(Employee, pk=employee_id)
    # generate a membership form for the given employee
    MembershipForm = make_membership_form(employee)
    MembershipFormSet = modelformset_factory(Membership, form=MembershipForm)

    if request.method == "POST":
        formset = MembershipFormSet(request.POST, queryset=Membership.objects.filter(employee=employee))
        if formset.is_valid():
            instances = formset.save(commit=False)
                for member in instances:
                    member.employee = employee
                    member.department = employee.department
                    member.save()
            formset.save_m2m()
            # redirect after successful update
            return HttpResponseRedirect("")
    else:
        formset = MembershipFormSet(queryset=Membership.objects.filter(employee=employee),)
    return render_to_response('testdb/edit.html', {'item': employee, 'formset': formset, }, context_instance=RequestContext(request))

Answer 2

编辑

该死。所有这些打字都是因为我错过了一部分代码；）。正如 @Alasdair 在 cmets 中提到的那样，您已将 department 从表单中排除，因此您可以使用 Django 来限制它。不过，我将保留我原来的答案，以防万一它可能对其他人有所帮助。

根据您的情况，您只需要：

class MembershipForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super(MembershipForm, self).__init__(*args, **kwargs)
        self.fields['project'].queryset = self.fields['project'].queryset.filter(department_id=self.instance.department_id)

然后：

MembershipFormSet = modelformset_factory(Membership, form=MembershipForm, exclude=('department', 'employee'),)

原始答案（供后代使用）

您不能在 Django 中对此进行限制，因为部门的值是可变的，因此项目列表可能会根据当前选择的特定部门而有所不同。为了验证表单，您必须向 Django 提供所有可能允许的项目，因此您唯一的选择是 AJAX。

创建一个视图，该视图将返回一个 JSON 响应，其中包含馈入视图的特定部门的项目。大致如下：

from django.http import HttpResponse, HttpResponseBadRequest
from django.shortcuts import get_list_or_404
from django.utils import simplejson

def ajax_department_projects(request):
    department_id = request.GET.get('department_id')
    if department_id is None:
        return HttpResponseBadRequest()

    project_qs = Project.objects.select_related('department', 'project_type')
    projects = get_list_or_404(project_qs, department__id=department_id)
    data = []
    for p in projects:
        data.append({
            'id': p.id,
            'name': unicode(p),
        })

    return HttpResponse(simplejson.dumps(data), mimetype='application/json')

然后，创建一些 JavaScript 来在更改部门选择框时获取此视图：

(function($){
    $(document).ready(function(){
        var $department = $('#id_department');
        var $project = $('#id_project');

        function updateProjectChoices(){
            var selected = $department.val();
            if (selected) {
                $.getJSON('/path/to/ajax/view/', {department_id: selected}, function(data, jqXHR){
                    var options = [];
                    for (var i=0; i<data.length; i++) {
                        output = '<option value="'+data[i].id+'"';
                        if ($project.val() == data[i].id) {
                            output += ' selected="selected"';
                        }
                        output += '>'+data[i].name+'</option>';
                        options.push(output);
                    }
                    $project.html(options.join(''));
                });
            }
        }

        updateProjectChoices();
        $project.change(updateProjectChoices);
    });
})(django.jQuery);