10 Form表单

一：什么是Form？什么是Django Form

Django的表单系统中,所有的表单类都作为django.forms.Form的子类创建,包括ModelForm

关于django的表单系统，主要分为两种：

• 基于django.forms.Form：所有表单类的父类
• 基于django.forms.ModelForm：可以和模型类绑定的Form

案例：实现添加出版社信息的功能

不使用Django Form的情况

建立urls映射，在views里添加逻辑代码

if request.method == "POST":
    # 如果是POST,接收用户输入
    name = request.POST['name']
    address = request.POST['address']
    city = request.POST['city']
    state_province = request.POST['state_province']
    country = request.POST['country']
    website = request.POST['website']
    
    # 这里最好要做非空验证
    Publisher.objects.create(
        name=name,
        address=address,
        city=city,
        state_province=state_province,
        country=country,
        website=website,
    )
    return HttpResponse("添加出版社信息成功")
else:
    return render(request, "add.html", locals())

add.html 内容

    {% csrf_token %}
    名称：

    地址：

    城市：

    省 ：

    国家：

    网站：

    提交：

使用Form的情况

在app里新建forms.py，添加代码:

from django import forms


class Publisher(forms.Form):
    name = forms.CharField()
    address = forms.CharField()
    city = forms.CharField()
    state_province = forms.CharField()
    country = forms.CharField()
    website = forms.URLField()

views代码修改成:

from hello.forms import PublisherForm

if request.method == "POST":
    # 如果是POST,接收用户输入
    publisher_form = PublisherForm(request.POST)
    # 表单验证
    if publisher_form.is_valid():
        # 这里最好要做非空验证
        Publisher.objects.create(
            name=publisher_form.cleaned_data['name'],
            address=publisher_form.cleaned_data['address'],
            city=publisher_form.cleaned_data['city'],
            state_province=publisher_form.cleaned_data['state_province'],
            country=publisher_form.cleaned_data['country'],
            website=publisher_form.cleaned_data['website'],
        )
        return HttpResponse("添加出版社信息成功")
else:
    publisher_form = PublisherForm()
return render(request, "add.html", locals())

实例化PublisherForm(),传入模板中

模板简化成：

    {% csrf_token %}
    {{ publisher_form.as_p }}
    提交：

# as_p p标签  还有 as_table  还有as_ul

使用ModelForm的情况

首先forms简化了

from django import forms
from hello.models import Publisher


class PublisherForm(forms.ModelForm):
    class Meta:
        model = Publisher     
        # fields设置绑定到forms的 exclude设置不绑定的    
        exclude = ("id", )

views也更简单了

if request.method == "POST":
    # 如果是POST,接收用户输入
    publisher_form = PublisherForm(request.POST)
    # 表单验证
    if publisher_form.is_valid():
        # 这里最好要做非空验证
        publisher_form.save()
        return HttpResponse("添加出版社信息成功")
else:
    publisher_form = PublisherForm()
return render(request, "add.html", locals())

哈 少了很多~~~

总结：Django Form可以大大简化代码，常用的表单功能特性都整合到了Form中，ModelForm可以和Model进行绑定，更进一步简化代码

---

关于Form的验证:

表单-->自定义验证

1. 表单字段的验证器
2. clean_filename,验证字段，针对某个字段进行验证
3. 表单clean方法，可针对整个表单进行验证

案例：自定义验证,不能插入重复的出版社名称

1.表单字段的验证器

from django import forms
from hello.models import Publisher
from django.core.exceptions import ValidationError


def validate_name(vaule):
    try:
        Publisher.objects.get(name=vaule)
        raise ValidationError("%s的信息已经存在" % vaule)
    except Publisher.DoesNotExist:
        pass


class PublisherForm(forms.ModelForm):
    name = forms.CharField(label="名称", validators=[validate_name])
    
    class Meta:
        model = Publisher
        # fields设置绑定到forms的 exclude设置不绑定的
        exclude = ("id", )

2. clean_filename,验证字段，针对某个字段进行验证

class PublisherForm(forms.ModelForm):

    def clean_name(self):
        vaule = self.cleaned_data.get("name")
        try:
            Publisher.objects.get(name=vaule)
            raise ValidationError("%s的信息已经存在llllllllll" % vaule)
        except Publisher.DoesNotExist:
            pass
        return value

    class Meta:
        model = Publisher
        # fields设置绑定到forms的 exclude设置不绑定的
        exclude = ("id", )

3. 表单clean方法，可针对整个表单进行验证

class PublisherForm(forms.ModelForm):

    def clean(self):
        cleaned_data = super(PublisherForm, self).clean()
        vaule1 = cleaned_data.get("name")
        vaule2 = cleaned_data.get("address")
        if vaule1 != vaule2:
            self._errors['address'] = self.error_class(["信息不一致"])
        return cleaned_data

    class Meta:
        model = Publisher
        # fields设置绑定到forms的 exclude设置不绑定的
        exclude = ("id", )

由于clean方法是获取的全部的数据,所有对于判断表单中关系的的字段 尤其好用