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Django之ModelForm

简介

Model + Form ==> ModelForm。model和form的结合体,所以有以下功能:

  • 验证
  • 数据库操作

Form回顾

models.py

class UserType(models.Model):
    caption = models.CharField(max_length=32)

class UserInfo(models.Model):
    username = models.CharField(max_length=32)
    email = models.EmailField()
    user_type = models.ForeignKey(to='UserType',to_field='id')

forms.py

from django import forms
from django.forms import fields

class UserInfoForm(forms.Form):
    # username = models.CharField(max_length=32)    <-- models
    username = fields.CharField(max_length=32)
    # email = models.EmailField()    <-- models
    email = fields.EmailField()
    # user_type = models.ForeignKey(to='UserType',to_field='id')    <-- models
    user_type = fields.ChoiceField(
        choices=models.UserType.objects.values_list('id','caption')
    )

    # 下面的操作是让数据在网页上实时更新。
    def __init__(self, *args, **kwargs):
        super(UserInfoForm,self).__init__(*args, **kwargs)
        self.fields['user_type'].choices = models.UserType.objects.values_list('id','caption')

index.html

<body>
    <form action="/index/" method="POST" novalidate="novalidate">
        {% csrf_token %}
        {{ obj.as_p }}
        <input type="submit" value="提交">
    </form>
</body>

  从上面的小例子能看出,models的字段和forms的字段大部分都是重复的,所以,django给我们提供了一种更为简洁的ModelFrom

ModelForm的用法

forms.py

class UserInfoModelForm(forms.ModelForm):

    class Meta:
        model = models.UserInfo    # 与models建立了依赖关系
        fields = "__all__"

views.py

def index(request):
    if request.method == "GET":
        obj = UserInfoModelForm()
        return render(request,"index.html",{'obj':obj})
    elif request.method == "POST":
        obj = UserInfoModelForm(request.POST)
        print(obj.is_valid())  # 这是方法,别忘记了加括号
        print(obj.cleaned_data)
        print(obj.errors)
        return render(request,"index.html",{'obj':obj})

index.html

<body>
    <form action="/index/" method="POST" novalidate="novalidate">
        {% csrf_token %}
        {{ obj.as_p }}
        <input type="submit" value="提交">
    </form>
</body>

ModelForm常见参数

自定义字段名(html显示的字段)

如何定义http上定义的字段呢,自定义写成中文的?之前的用法是在Form里写上label。Model Form定义要用verbose_name

指定显示那些字段

class UserInfo(models.Model):
    username = models.CharField(max_length=32, verbose_name='用户')
    email = models.EmailField(verbose_name='邮箱')
    user_type = models.ForeignKey(to='UserType',to_field='id', verbose_name='类型')

如果不在model里定义,在modelForm里实现,利用labels

class UserInfoModelForm(forms.ModelForm):

    class Meta:
        model = models.UserInfo
        fields = "__all__"
        labels = {
            'username':'用户名',
            'email':'邮箱',
        }

指定需要展示的字段

fields = "__all__"上面展示所有的,也可以展示指定的列

 fields = ['username','email']   # 显示指定列
 exclude = ['username']          # 排除指定列

错误信息

 error_messages = {
            '__all__':{    # 整体错误信息

            },
            'email': {
                'required': '邮箱不能为空',
                'invalid': '邮箱格式错误..',
            }
        }

给字段添加css属性

widgets = {
            'username': Fwidgets.Textarea(attrs={'class': 'c1'})
        }

ModelForm的验证

跟form一样,ModleForm里面也有is_validcleaned_dataerrors

# Form验证:
    UserInfoForm -> Form -> BaseForm( 包含is_valid等方法)

# ModelForm验证:
    UserInfoModelForm -> ModelForm -> BaseModelForm -> BaseForm

ModelForm对数据库操作

添加数据

如果数据验证通过,直接调用save()方法,django会自动往数据库里添加一条数据(会根据modles里的字段一一对应)

if obj.is_valid():
     obj.save()      # 创建数据

如果在如下一对多、多对多关系中,如:

class UserType(models.Model):
    caption = models.CharField(max_length=32)

class UserGroup(models.Model):
    name = models.CharField(max_length=32)

class UserInfo(models.Model):
    username = models.CharField(max_length=32)
    email = models.EmailField()
    user_type = models.ForeignKey(to='UserType',to_field='id')
    u2g = models.ManyToManyField(UserGroup)

这样的话,执行上面的obj.save()会自动在UserInfo表和多对多关系表里都增加数据,灰常灰常方便。

def index(request):
    if request.method == "GET":
        obj = UserInfoModelForm()
        return render(request,'index.html',{'obj': obj})
    elif request.method == "POST":
        obj = UserInfoModelForm(request.POST)
        if obj.is_valid():
            obj.save()  # 等价以下三句
            # instance = obj.save(False)
            # instance.save()
            # obj.save_m2m()
        return render(request,'index.html',{'obj': obj})

修改数据

修改表数据是,记得把instance信息也传进去,如:mf = UserInfoModelForm(request.POST,instance=user_obj)

不然是新建数据,而不是对某行数据进行修改。

编辑用户信息,新url方式保留默认数据

urls.py

url(r'^user_list/', views.user_list),
url(r'^edit-(\d+)/', views.user_edit),

views.py

def user_list(request):
    li = models.UserInfo.objects.all().select_related('user_type')  # 这里只能是外键,多对多字段也不可以
    return render(request,'user_list.html',{'li': li})

def user_edit(request, nid):
    # 获取当前id对象的用户信息
    # 显示用户已经存在数据
    if request.method == "GET":
        user_obj = models.UserInfo.objects.filter(id=nid).first()
        mf = UserInfoModelForm(instance=user_obj)   # 把默认数据传递进去
        return render(request,'user_edit.html',{'mf': mf, 'nid': nid})
    elif request.method == 'POST':
        # 数据修改的信息,给数据库的哪一行做修改?
        user_obj = models.UserInfo.objects.filter(id=nid).first()
        mf = UserInfoModelForm(request.POST,instance=user_obj)  # 指定给谁做修改
        if mf.is_valid():
            mf.save()
        else:
            print(mf.errors.as_json())
        return render(request,'user_edit.html',{'mf': mf, 'nid': nid})

user_list.html

<body>
    <ul>
        {% for row in li %}
            <li>{{ row.username }} - {{ row.user_type.caption }} - <a href="/edit-{{ row.id }}/">编辑</a></li>
        {% endfor %}
    </ul>
</body>

user_edit.html

<body>
    <form method="POST" action="/edit-{{ nid }}/">
        {% csrf_token %}
    {{ mf.as_p }}
        <input type="submit" value="提交" />
    </form>
</body>

  

 
 
 
posted @ 2018-05-03 17:07  PythonAV  阅读(242)  评论(0编辑  收藏  举报