django的forms

base知识

参考博文：https://www.cnblogs.com/yuanchenqi/articles/9036474.html

用户表单是Web端的一项基本功能,大而全的Django框架中自然带有现成的基础form对象,Python的Django框架中forms表单类的使用方法详解

1，demo1
	form表单的那么属性值对应UserForm属性值
	class UserForm(forms.Form): 
		name=forms.CharField(min_length=4) 	
		pwd=forms.CharField(min_length=4)
	form=UserForm({"name":"yuan","email":"123"})
	print(form.is_valid()) # 返回布尔值
2，form渲染组件
	{{ form.name }}

Form表单的功能

自动生成HTML表单元素
检查表单数据的合法性
如果验证错误，重新显示表单（数据不会重置）
数据类型转换（字符类型的数据转换成相应的Python类型）

Form相关的对象包括

Widget：用来渲染成HTML元素的工具，如：forms.Textarea对应HTML中的<textarea>标签
Field：Form对象中的一个字段，如：EmailField表示email字段，如果这个字段不是有效的email格式，就会产生错误。
Form：一系列Field对象的集合，负责验证和显示HTML元素
Form Media：用来渲染表单的CSS和JavaScript资源。

forms里面的字段：

required：是否可以为空。required=True 不可以为空，required=False 可以为空
max_length=4 最多4个值，超过不会显示
min_length=2 至少两个值，少于两个会返回提示信息
error_messages={'required': '邮箱不能为空', 'invalid': '邮箱格式错误'}  自定义错误信息，invalid 是格式错误
widget=forms.TextInput(attrs={'class': 'c1'}) 给自动生成的input标签自定义class属性
widget=forms.Textarea()  生成Textarea标签。widget默认生成input标签

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校验字段功能

精简示例：

form表单校验字段

from django import forms
class UserForm(forms.Form):
    name=forms.CharField(min_length=4,label="用户名")
    pwd=forms.CharField(min_length=4)
    r_pwd=forms.CharField(min_length=4)
    email=forms.EmailField()
    tel=forms.CharField()

class reg(request):
    if request.method=="POST":
        # form=UserForm({"name":"yuan","email":"123"})
        
        form=UserForm(request.POST)
        
        print(form.is_valid())
        if form.is_valid():
            print(form.cleaned_data)
        else:
            print(form.cleaned_data) # 正确的键值对
            print(form.errors) # 错误的键：错误的信息
        return HttpResponse("ok")
    return render(request,"reg.html")

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针对一个实例：注册用户讲解。

模型：models.py

class UserInfo(models.Model):
    name=models.CharField(max_length=32)
    pwd=models.CharField(max_length=32)
    email=models.EmailField()
    tel=models.CharField(max_length=32)

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模板: register.html:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

</head>
<body>

<form action="" method="post">
    {% csrf_token %}
    <div>
        <label for="user">用户名</label>
        <p><input type="text" name="name" id="name"></p>
    </div>
    <div>
        <label for="pwd">密码</label>
        <p><input type="password" name="pwd" id="pwd"></p>
    </div>
    <div>
        <label for="r_pwd">确认密码</label>
        <p><input type="password" name="r_pwd" id="r_pwd"></p>
    </div>
     <div>
        <label for="email">邮箱</label>
        <p><input type="text" name="email" id="email"></p>
    </div>
    <input type="submit">
</form>

</body>
</html>

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视图函数：register

# forms组件
from django.forms import widgets

wid_01=widgets.TextInput(attrs={"class":"form-control"})
wid_02=widgets.PasswordInput(attrs={"class":"form-control"})

class UserForm(forms.Form):
    name=forms.CharField(max_length=32,
                         widget=wid_01
                         )
    pwd=forms.CharField(max_length=32,widget=wid_02)
    r_pwd=forms.CharField(max_length=32,widget=wid_02)
    email=forms.EmailField(widget=wid_01)
    tel=forms.CharField(max_length=32,widget=wid_01)



def register(request):

    if request.method=="POST":
        form=UserForm(request.POST)
        if form.is_valid():
            print(form.cleaned_data)       # 所有干净的字段以及对应的值
        else:
            print(form.cleaned_data)       #
            print(form.errors)             # ErrorDict : {"校验错误的字段":["错误信息",]}
            print(form.errors.get("name")) # ErrorList ["错误信息",]
        return HttpResponse("OK")
    form=UserForm()
    return render(request,"register.html",locals())

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渲染标签功能

精简示例：

渲染标签
方式1
form=UserForm()
return render(request,"reg.html",locals())
<p>用户名：{{form.name}}</p>
<p>{{form.name.label}}：{{form.name}}</p>
方式2
{% csrf_token %}
{% for field in form %}
    <div>
        <label for="">{{field.label}}</label>
        {{field}}
    </div>
{% endfor %}

方式3 # 了解，不建议使用
{% csrf_token %}
{{form as_p}}

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渲染方式1

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
   <!-- 最新版本的 Bootstrap 核心 CSS 文件 -->
    <link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
</head>
<body>
<h3>注册页面</h3>
<div class="container">
    <div class="row">
        <div class="col-md-6 col-lg-offset-3">

                <form action="" method="post">
                    {% csrf_token %}
                    <div>
                        <label for="">用户名</label>
                        {{ form.name }}
                    </div>
                    <div>
                        <label for="">密码</label>
                        {{ form.pwd }}
                    </div>
                    <div>
                        <label for="">确认密码</label>
                        {{ form.r_pwd }}
                    </div>
                    <div>
                        <label for=""> 邮箱</label>
                        {{ form.email }}
                    </div>

                    <input type="submit" class="btn btn-default pull-right">
                </form>
        </div>
    </div>
</div>



</body>
</html>

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渲染方式2

<form action="" method="post">
                    {% csrf_token %}
                    
                    {% for field in form %}
                        <div>
                            <label for="">{{ field.label }}</label>
                            {{ field }}
                        </div>
                    {% endfor %}
                    <input type="submit" class="btn btn-default pull-right">
                
</form>

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渲染方式3

<form action="" method="post">
    {% csrf_token %}
    
    {{ form.as_p }}
    <input type="submit" class="btn btn-default pull-right">

</form>

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显示错误与重置输入信息功能

精简示例：

渲染错误信息
<p>{{form.name.label}}：{{form.name}}<span>{{form.name.errors.0}}</span></p>

forms组件的参数配置
from django.forms import widgets

name=forms.CharField(min_length=4,label="用户名",error_message={"required":"该字段不能为空"})
pwd=forms.CharField(min_length=4,label="密码",widgets=widgets.PasswordInput(attrs={"class":"form-control"}))

email=forms.EmailField(label="邮箱",error_message={"required":"该字段不能为空","invalid":"格式错误"})

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视图

def register(request):

    if request.method=="POST":
        form=UserForm(request.POST)
        if form.is_valid():
            print(form.cleaned_data)       # 所有干净的字段以及对应的值
        else:
            print(form.cleaned_data)       #
            print(form.errors)             # ErrorDict : {"校验错误的字段":["错误信息",]}
            print(form.errors.get("name")) # ErrorList ["错误信息",]
        return render(request,"register.html",locals())
    form=UserForm()
    return render(request,"register.html",locals())

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模板

<form action="" method="post" novalidate>
    {% csrf_token %}
    
    {% for field in form %}
        <div>
            <label for="">{{ field.label }}</label>
            {{ field }} <span class="pull-right" style="color: red">{{ field.errors.0 }}</span>
        </div>
    {% endfor %}
    <input type="submit" class="btn btn-default">

</form>

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局部钩子与全局钩子

精简示例：

钩子

from django.core.exceptions import ValidationError
def clean_name(self):
    val = self.cleaned_data.get("name")
    ret = UserInfo.objects.filter(name=val)
    if not ret:
        return val
    else:
        raise ValidationError("该用户已经注册！")


全局钩子
def clean(self):
    pwd = self.cleaned_data.get("pwd")
    r_pwd = self.cleaned_data.get("r_pwd")
    if pwd and r_pwd: # 都不为空
        if pwd == r_pwd:
            return self.cleaned_data
        else:
            raise ValidationError("俩次密码不一致")
    else:
        return self.cleaned_data
全局错误        
print("error",form.errors.get("__all__")[0])
errors = form.errors.get("__all__")        

return render(request,"reg.html",locals())
<p>{{form.name.label}}：{{form.name}}<span class="pull-right error">{{form.name.errors.0}}</span></p>

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模板

# forms组件
from django.forms import widgets

wid_01=widgets.TextInput(attrs={"class":"form-control"})
wid_02=widgets.PasswordInput(attrs={"class":"form-control"})

from django.core.exceptions import ValidationError
class UserForm(forms.Form):
    name=forms.CharField(max_length=32,
                         widget=wid_01
                         )
    pwd=forms.CharField(max_length=32,widget=wid_02)
    r_pwd=forms.CharField(max_length=32,widget=wid_02)
    email=forms.EmailField(widget=wid_01)
    tel=forms.CharField(max_length=32,widget=wid_01)


    # 局部钩子
    def clean_name(self):
        val=self.cleaned_data.get("name")
        if not val.isdigit():
            return val
        else:
            raise ValidationError("用户名不能是纯数字!")

    # 全局钩子

    def clean(self):
        pwd=self.cleaned_data.get("pwd")
        r_pwd=self.cleaned_data.get("r_pwd")

        if pwd==r_pwd:
            return self.cleaned_data
        else:
            raise ValidationError('两次密码不一致!')


def register(request):

    if request.method=="POST":
        form=UserForm(request.POST)
        if form.is_valid():
            print(form.cleaned_data)       # 所有干净的字段以及对应的值
        else:
            clean_error=form.errors.get("__all__")

        return render(request,"register.html",locals())
    form=UserForm()
    return render(request,"register.html",locals())

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视图

<form action="" method="post" novalidate>
            {% csrf_token %}

            {% for field in form %}
                <div>
                    <label for="">{{ field.label }}</label>
                    {{ field }}
                    <span class="pull-right" style="color: red">
                          {% if field.label == 'R pwd' %}
                          <span>{{ clean_error.0 }}</span>
                          {% endif %}
                          {{ field.errors.0 }}
                    </span>
                </div>
            {% endfor %}
            <input type="submit" class="btn btn-default">

</form>

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