Django的Form组件

2020-02-17

本文阅读量：

原生Form组件缺点：

①无法记住上次提交的内容，刷新页面数据消失

②重复进行用户数据校验：正则，长度，是否为空

Django提供的Form组件可完成：

①数据验证 ②生成Html标签 ③保留上次输入内容

1. 数据验证定义规则

from django.forms import Form
from django.forms import fileds

class xxx(Form):
    xx=fields.CharField(
        required=True,max_lenth=18,min_lenth=6,
        error_message={
            'required': '用户名不能为空',
            'min_length': '太短了',
            'max_length': '太长了',
        }
    )

obj=xxx(request.POST)
obj.is_valid()  # 是否校验成功
obj.errors  # 错误信息
obj.cleaned_data  # 正确信息

'''
<p>用户：<input type="text" name="username">
html标签name属性需与Form类中的字段名xx一致
'''

2. 生成Html标签

class LoginForm(forms.Form):
    username_or_email = forms.CharField(
        label='用户名或邮箱',
        widget=forms.TextInput(
            attrs={'class': 'form-control', 'placeholder': '用户名或邮箱'}
        )
    )
'''
    widget=widgets.Textarea, 同于指定生成怎样的HTML标签，select、text、input等
    label='用户名',
    label_suffix='--->',
    help_text='提示',
    disabled=True,
    initial='默认值',
'''
def login(request):
    login_form = LoginForm()
    context['login_form'] = login_form
    return render(request, 'login.html', context)

{% for field in login_form %}
    {{ field }}
{% endfor %}

3. 保留上次输入的内容

'''
- GET
	obj=Form()
	Form生成HTML标签<input .../>

- POST
	obj=Form(request.POST)
	Form生成HTML标签<input ... value='xx'/>
'''

class RegisterForm(Form): 
    user = fields.CharField(min_length=8)
    password = fields.CharField()   
    phone = fields.RegexField('139\d+')
    
def login(request):
    if request.method == 'GET':
        return render(request, 'login.html')
    else:
        obj = LoginForm(request.POST)
        if obj.is_valid():
            print(obj.cleaned_data)
            return render(request, 'index.html')
        else:
            print(obj.errors)
        return render(request, 'login.html', {'obj': obj})

<form id="f1" method="post" action="/login/">
    {% csrf_token %}
    <p><input type="text" name="user">{{ obj.errors.user.0 }}</p>
    <p><input type="password" name="pwd">{{ obj.errors.pwd.0 }}</p>
    <p><input type="submit" value="提交"></p>
</form>

3. 内部原理

# 1. LoginForm实例化时，
self.fields={       
    'user':正则表达式       
    'pwd':正则表达式   
}

# 2. 循环self.fields
flag=True 
errors 
clean_data    
for k,v in self.field.items(): 
    # k是user,pwd     
    # v是正则表达式      
    input_value=request.POST.get(k)   
    # input_value和正则表达式进行匹配     
    # 不满足，flag=False  
return flag

数据验证+保留上次输入内容，可有以下两种方式实现：

①Django ‘s Form生成Html标签+验证数据

②Ajax提交数据+Django’s Form验证数据

方法一：Django ‘s Form

class LoginForm(forms.Form):
    username_or_email = forms.CharField(
        label='用户名或邮箱',
        widget=forms.TextInput(
            attrs={'class': 'form-control', 'placeholder': '用户名或邮箱'}
        )
    )
    password = forms.CharField(
        label='密码',
        widget=forms.PasswordInput(
            attrs={'class': 'form-control', 'placeholder': '密码'}
        )
    )

def login(request):
    context = {}
    if request.method == 'GET':
        login_form = LoginForm()
    else:
        login_form = LoginForm(request.POST)
        if login_form.is_valid():
            user = login_form.cleaned_data['user']
            auth.login(request, user)
            return redirect(request.GET.get('from', reverse('home')))
    context['login_form'] = login_form
    return render(request, 'login.html', context)

<form method="post">
    {% csrf_token %}
    {% for field in login_form %}
        <label for="{{ field.id_for_label }}">{{ field.label }}</label>
        {{ field }}
        <p class="text-danger">{{ field.errors.as_text }}</p>
    {% endfor %}
    <span class="text-danger">{{ login_form.non_field_errors }}</span>
    <div class="clearfix"></div>
    <a href="{% url 'forget_password' %}" class="pull-left">忘记密码</a>
    <input type="submit" value="登录" class="btn btn-primary pull-right">
</form>

Ajax+Django’s Form

class RegisterForm(Form): 
    user = fields.CharField(min_length=8)  
    email = fields.EmailField()   
    password = fields.CharField()   
    phone = fields.RegexField('139\d+')

def login(request):
    return render(request, 'login.html')

def ajax_login(request):
    ret = {'status': True, 'msg': None}
    obj = LoginForm(request.POST)
    if obj.is_valid():
        print(obj.cleaned_data)
    else:
        import json
        ret['status'] = False
        ret['msg'] = obj.errors
    v = json.dumps(ret)
    return HttpResponse(v)

<form id="f1" method="post" action="/login/">
    {% csrf_token %}
    <p><input type="text" name="user">{{ obj.errors.user.0 }}</p>
    <p><input type="password" name="pwd">{{ obj.errors.pwd.0 }}</p>
    <a onclick="submitForm();">Ajax提交</a>
</form>


<script src="/static/jquery-1.10.2.js"></script>
<script>
    function submitForm() {
        $('.c1').remove();
        $.ajax({
            url: '/ajax_login/',
            type: 'POST',
            data: $('#f1').serialize(),//user=xxx&pwd=xxx&csrftoken=xxx
            dataType: 'JSON',
            success: function (arg) {
                console.log(arg)
                if (arg.status) {

                } else {
                    $.each(arg.msg, function (index, value) {
                        console.log(index, value);
                        var tag = document.createElement('span');
                        tag.innerHTML = value[0];
                        tag.className='c1';
                        $('#f1').find('input[name="'+index+'"]').after(tag);
                    })
                }
            }
        })
    }
</script>