Form介紹
我們之前在HTML頁面中利用form表單向后端提交數據時，都會寫一些獲取用戶輸入的標簽並且用form標簽把它們包起來。
與此同時我們在好多場景下都需要對用戶的輸入做校驗，比如校驗用戶是否輸入，輸入的長度和格式等正不正確。如果用戶輸入的內容有錯誤就需要在頁面上相應的位置顯示顯示對應的錯誤信息.。
Django form組件就實現了上面所述的功能。
總結一下，其實form組件的主要功能如下:
- 生成頁面可用的HTML標簽
- 對用戶提交的數據進行校驗
- 保留上次輸入內容
普通的登錄
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 = "用戶名或密碼錯誤"
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">用戶名</label>
<input type="text" name="username" id="username">
</p>
<p>
<label for="pwd">密碼</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>
使用form組件
views.py
先定義好一個LoginForm類。
class LoginForm(forms.Form):
username = forms.CharField(min_length=8, label="用戶名")
pwd = forms.CharField(min_length=6, label="密碼")
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 = "用戶名或密碼錯誤"
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>
看網頁效果發現 也驗證了form的功能：
• 前端頁面是form類的對象生成的 -->生成HTML標簽功能
• 當用戶名和密碼輸入為空或輸錯之后 頁面都會提示 -->用戶提交校驗功能
• 當用戶輸錯之后 再次輸入 上次的內容還保留在input框 -->保留上次輸入內容
Form那些事兒
常用字段演示
initial
初始值，input框里面的初始值。
class LoginForm(forms.Form):
username = forms.CharField(
min_length=8,
label="用戶名",
initial="張三" # 設置默認值
)
pwd = forms.CharField(min_length=6, label="密碼")
error_messages
重寫錯誤信息。
class LoginForm(forms.Form):
username = forms.CharField(
min_length=8,
label="用戶名",
initial="張三",
error_messages={
"required": "不能為空",
"invalid": "格式錯誤",
"min_length": "用戶名最短8位"
}
)
pwd = forms.CharField(min_length=6, label="密碼")
password
class LoginForm(forms.Form):
...
pwd = forms.CharField(
min_length=6,
label="密碼",
widget=forms.widgets.PasswordInput(attrs={'class': 'c1'}, render_value=True)
)
radioSelect
單radio值為字符串
class LoginForm(forms.Form):
username = forms.CharField(
min_length=8,
label="用戶名",
initial="張三",
error_messages={
"required": "不能為空",
"invalid": "格式錯誤",
"min_length": "用戶名最短8位"
}
)
pwd = forms.CharField(min_length=6, label="密碼")
gender = forms.fields.ChoiceField(
choices=((1, "男"), (2, "女"), (3, "保密")),
label="性別",
initial=3,
widget=forms.widgets.RadioSelect
)
單選Select
class LoginForm(forms.Form):
...
hobby = forms.fields.ChoiceField(
choices=((1, "籃球"), (2, "足球"), (3, "雙色球"), ),
label="愛好",
initial=3,
widget=forms.widgets.Select
)
多選Select
class LoginForm(forms.Form):
...
hobby = forms.fields.MultipleChoiceField(
choices=((1, "籃球"), (2, "足球"), (3, "雙色球"), ),
label="愛好",
initial=[1, 3],
widget=forms.widgets.SelectMultiple
)
單選checkbox
class LoginForm(forms.Form):
...
keep = forms.fields.ChoiceField(
label="是否記住密碼",
initial="checked",
widget=forms.widgets.CheckboxInput
)
多選checkbox
class LoginForm(forms.Form):
...
hobby = forms.fields.MultipleChoiceField(
choices=((1, "籃球"), (2, "足球"), (3, "雙色球"),),
label="愛好",
initial=[1, 3],
widget=forms.widgets.CheckboxSelectMultiple
)
關於choice的注意事項：
在使用選擇標簽時，需要注意choices的選項可以從數據庫中獲取，但是由於是靜態字段 ***獲取的值無法實時更新***，那么需要自定義構造方法從而達到此目的。
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())
Django form內置字段
校驗
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]+$', '請輸入數字'), RegexValidator(r'^159[0-9]+$', '數字必須以159開頭')],
)
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
# 自定義驗證規則
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('手機號碼格式錯誤')
class PublishForm(Form):
title = fields.CharField(max_length=20,
min_length=5,
error_messages={'required': '標題不能為空',
'min_length': '標題最少為5個字符',
'max_length': '標題最多為20個字符'},
widget=widgets.TextInput(attrs={'class': "form-control",
'placeholder': '標題5-20個字符'}))
# 使用自定義驗證規則
phone = fields.CharField(validators=[mobile_validate, ],
error_messages={'required': '手機不能為空'},
widget=widgets.TextInput(attrs={'class': "form-control",
'placeholder': u'手機號碼'}))
email = fields.EmailField(required=False,
error_messages={'required': u'郵箱不能為空','invalid': u'郵箱格式錯誤'},
widget=widgets.TextInput(attrs={'class': "form-control", 'placeholder': u'郵箱'}))
補充進階
應用Bootstrap樣式
復制代碼 <!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">注冊</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> 復制代碼
批量添加樣式
可通過重寫form類的init方法來實現。
復制代碼 class LoginForm(forms.Form): username = forms.CharField( min_length=8, label="用戶名", initial="張三", error_messages={ "required": "不能為空", "invalid": "格式錯誤", "min_length": "用戶名最短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' }) 復制代碼