FORM表单

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FORM简介

我们之前在html页面中利用form表单向后端提交数据时，都会写一些获取用户输入的标签并且用form标签把它们包起来。

与此同时我们在好多场景下都需要对用户的输入做校验，比如校验用户是否输入，输入的长度和格式等正不正确。如果用户输入的内容有错误就需要在页面上相应的位置显示显示对应的错误信息.。

Django form组件就实现了上面所述的功能。

总结一下，其实form组件的主要功能如下:

生成页面可用的HTML标签
对用户提交的数据进行校验
保留上次输入内容

普通的登陆

views.py

def login(request):
    error_msg = ""
    if request.method == "POST":
        username = request.POST.get("username")
        pwd = request.POST.get("pwd")
        if username == "Q1mi" and pwd == "123456":
            return HttpResponse("OK")
        else:
            error_msg = "用户名或密码错误"
    return render(request, "login.html", {"error_msg": error_msg})

login.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="x-ua-compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>login</title>
  <style>
    .error {
      color: red;
    }
  </style>
</head>
<body>
<form action="/login/" method="post">
  {% csrf_token %}
  <p>
    <label for="username">用户名</label>
    <input type="text" name="username" id="username">
  </p>
  <p>
    <label for="pwd">密码</label>
    <input type="password" name="pwd" id="pwd">
    <span class="error"></span>
  </p>
  <p>
    <input type="submit">
    <span class="error">{{ error_msg }}</span>
  </p>
</form>
</body>
</html>

form组件登陆

views.py

先定义好一个LoginForm类。

class LoginForm(forms.Form):
    username = forms.CharField(min_length=8, label="用户名")
    pwd = forms.CharField(min_length=6, label="密码")


def login2(request):
    error_msg = ""
    form_obj = LoginForm()
    if request.method == "POST":
        form_obj = LoginForm(request.POST)
        if form_obj.is_valid():
            username = form_obj.cleaned_data.get("username")
            pwd = form_obj.cleaned_data.get("pwd")
            if username == "Q1mi" and pwd == "123456":
                return HttpResponse("OK")
            else:
                error_msg = "用户名或密码错误"
    return render(request, "login2.html", {"form_obj": form_obj, "error_msg": error_msg})

login2.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="x-ua-compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>login</title>
  <style>
    .error {
      color: red;
    }
  </style>
</head>
<body>
<form action="/login2/" method="post" novalidate>
  {% csrf_token %}
  <p>
    {{ form_obj.username.label }}
    {{ form_obj.username }}
    <span class="error">{{ form_obj.username.errors.0 }}</span>
  </p>
  <p>
    {{ form_obj.pwd.label }}
    {{ form_obj.pwd }}
    <span class="error">{{ form_obj.pwd.errors.0 }}</span>
  </p>
  <p>
    <input type="submit">
    <span class="error">{{ error_msg }}</span>
  </p>
</form>
</body>
</html>

看网页效果发现 也验证了form的功能：
• 前端页面是form类的对象生成的                                      -->生成HTML标签功能
• 当用户名和密码输入为空或输错之后 页面都会提示        -->用户提交校验功能
• 当用户输错之后 再次输入 上次的内容还保留在input框   -->保留上次输入内容

FORM常用字段

initial

初始值，input框里面的初始值。

class LoginForm(forms.Form):
    username = forms.CharField(
        min_length=8,
        label="用户名",
        initial="张三"  # 设置默认值
    )
    pwd = forms.CharField(min_length=6, label="密码")

error_messages

重写错误信息。

class LoginForm(forms.Form):
    username = forms.CharField(
        min_length=8,
        label="用户名",
        initial="张三",
        error_messages={
            "required": "不能为空",
            "invalid": "格式错误",
            "min_length": "用户名最短8位"
        }
    )
    pwd = forms.CharField(min_length=6, label="密码")

password

class LoginForm(forms.Form):
    ...
    pwd = forms.CharField(
        min_length=6,
        label="密码",
        widget=forms.widgets.PasswordInput(attrs={‘class‘: ‘c1‘}, render_value=True)
    )

radioselect

单radio值为字符串

class LoginForm(forms.Form):
    username = forms.CharField(
        min_length=8,
        label="用户名",
        initial="张三",
        error_messages={
            "required": "不能为空",
            "invalid": "格式错误",
            "min_length": "用户名最短8位"
        }
    )
    pwd = forms.CharField(min_length=6, label="密码")
    gender = forms.fields.ChoiceField(
        choices=((1, "男"), (2, "女"), (3, "保密")),
        label="性别",
        initial=3,
        widget=forms.widgets.RadioSelect
    )

单选Select

class LoginForm(forms.Form):
    ...
    hobby = forms.fields.ChoiceField(
        choices=((1, "篮球"), (2, "足球"), (3, "双色球"), ),
        label="爱好",
        initial=3,
        widget=forms.widgets.Select
    )

多选Select

class LoginForm(forms.Form):
    ...
    hobby = forms.fields.MultipleChoiceField(
        choices=((1, "篮球"), (2, "足球"), (3, "双色球"), ),
        label="爱好",
        initial=[1, 3],
        widget=forms.widgets.SelectMultiple
    )

单选checkbox

class LoginForm(forms.Form):
    ...
    keep = forms.fields.ChoiceField(
        label="是否记住密码",
        initial="checked",
        widget=forms.widgets.CheckboxInput
    )

多选checkbox

class LoginForm(forms.Form):
    ...
    hobby = forms.fields.MultipleChoiceField(
        choices=((1, "篮球"), (2, "足球"), (3, "双色球"),),
        label="爱好",
        initial=[1, 3],
        widget=forms.widgets.CheckboxSelectMultiple
    )

关于choice的注意事项：

在使用选择标签时，需要注意choices的选项可以从数据库中获取，但是由于是静态字段 ***获取的值无法实时更新***，那么需要自定义构造方法从而达到此目的。

方式一：

from django.forms import Form
from django.forms import widgets
from django.forms import fields

 
class MyForm(Form):
 
    user = fields.ChoiceField(
        # choices=((1, ‘上海‘), (2, ‘北京‘),),
        initial=2,
        widget=widgets.Select
    )
 
    def __init__(self, *args, **kwargs):
        super(MyForm,self).__init__(*args, **kwargs)
        # self.fields[‘user‘].widget.choices = ((1, ‘上海‘), (2, ‘北京‘),)
        # 或
        self.fields[‘user‘].widget.choices = models.Classes.objects.all().values_list(‘id‘,‘caption‘)

方式二：

from django import forms
from django.forms import fields
from django.forms import models as form_model

 
class FInfo(forms.Form):
    authors = form_model.ModelMultipleChoiceField(queryset=models.NNewType.objects.all())
    # authors = form_model.ModelChoiceField(queryset=models.NNewType.objects.all())

校验

方式一：

from django.forms import Form
from django.forms import widgets
from django.forms import fields
from django.core.validators import RegexValidator
 
class MyForm(Form):
    user = fields.CharField(
        validators=[RegexValidator(r‘^[0-9]+$‘, ‘请输入数字‘), RegexValidator(r‘^159[0-9]+$‘, ‘数字必须以159开头‘)],
    )

方式二：

import re
from django.forms import Form
from django.forms import widgets
from django.forms import fields
from django.core.exceptions import ValidationError
 
 
# 自定义验证规则
def mobile_validate(value):
    mobile_re = re.compile(r‘^(13[0-9]|15[012356789]|17[678]|18[0-9]|14[57])[0-9]{8}$‘)
    if not mobile_re.match(value):
        raise ValidationError(‘手机号码格式错误‘)
 
 
class PublishForm(Form):
 
 
    title = fields.CharField(max_length=20,
                            min_length=5,
                            error_messages={‘required‘: ‘标题不能为空‘,
                                            ‘min_length‘: ‘标题最少为5个字符‘,
                                            ‘max_length‘: ‘标题最多为20个字符‘},
                            widget=widgets.TextInput(attrs={‘class‘: "form-control",
                                                          ‘placeholder‘: ‘标题5-20个字符‘}))
 
 
    # 使用自定义验证规则
    phone = fields.CharField(validators=[mobile_validate, ],
                            error_messages={‘required‘: ‘手机不能为空‘},
                            widget=widgets.TextInput(attrs={‘class‘: "form-control",
                                                          ‘placeholder‘: u‘手机号码‘}))
 
    email = fields.EmailField(required=False,
                            error_messages={‘required‘: u‘邮箱不能为空‘,‘invalid‘: u‘邮箱格式错误‘},
                            widget=widgets.TextInput(attrs={‘class‘: "form-control", ‘placeholder‘: u‘邮箱‘}))

FORM应用BootStrap样式

技术分享图片 
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="x-ua-compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="/static/bootstrap/css/bootstrap.min.css">
  <title>login</title>
</head>
<body>
<div class="container">
  <div class="row">
    <form action="/login2/" method="post" novalidate class="form-horizontal">
      {% csrf_token %}
      <div class="form-group">
        <label for="{{ form_obj.username.id_for_label }}"
               class="col-md-2 control-label">{{ form_obj.username.label }}</label>
        <div class="col-md-10">
          {{ form_obj.username }}
          <span class="help-block">{{ form_obj.username.errors.0 }}</span>
        </div>
      </div>
      <div class="form-group">
        <label for="{{ form_obj.pwd.id_for_label }}" class="col-md-2 control-label">{{ form_obj.pwd.label }}</label>
        <div class="col-md-10">
          {{ form_obj.pwd }}
          <span class="help-block">{{ form_obj.pwd.errors.0 }}</span>
        </div>
      </div>
      <div class="form-group">
      <label class="col-md-2 control-label">{{ form_obj.gender.label }}</label>
        <div class="col-md-10">
          <div class="radio">
            {% for radio in form_obj.gender %}
              <label for="{{ radio.id_for_label }}">
                {{ radio.tag }}{{ radio.choice_label }}
              </label>
            {% endfor %}
          </div>
        </div>
      </div>
      <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
          <button type="submit" class="btn btn-default">注册</button>
        </div>
      </div>
    </form>
  </div>
</div>

<script src="/static/jquery-3.2.1.min.js"></script>
<script src="/static/bootstrap/js/bootstrap.min.js"></script>
</body>
</html>
View Code

批量添加样式

可通过重写form类的init方法来实现。

技术分享图片 
class LoginForm(forms.Form):
    username = forms.CharField(
        min_length=8,
        label="用户名",
        initial="张三",
        error_messages={
            "required": "不能为空",
            "invalid": "格式错误",
            "min_length": "用户名最短8位"
        }
    ...

    def __init__(self, *args, **kwargs):
        super(LoginForm, self).__init__(*args, **kwargs)
        for field in iter(self.fields):
            self.fields[field].widget.attrs.update({
                ‘class‘: ‘form-control‘
            })
View Code

 

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