前言：
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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录
views.py
def login(request): error_msg = "" if request.method == "POST": username = request.POST.get("username") pwd = request.POST.get("pwd") if username == "SKS" and pwd == "1366768": 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>使用form组件views.py
先定义好一个LoginForm类。
# 定义一个form组件类class LoginForm(forms.Form): # 验证的字段及条件 username = forms.CharField(min_length=10, label="用户名") pwd = forms.CharField(min_length=10, label="密码")def login(request): # 存储错误信息 error_msg = "" # 实例化对象 form_obj = LoginForm() # 判断前端页面请求是否是POST请求 if request.method == "POST": # 将数据传入form组件类中 form_obj = LoginForm(request.POST) # 存储的正确信息 if form_obj.is_valid(): username = form_obj.cleaned_data.get("username") pwd = form_obj.cleaned_data.get("pwd") if username == "SKS" and pwd == "1866768": 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组件
常用字段演示
initial
初始值，input框里面的初始值。
# 定义一个类继承forms.Formclass LoginForm(forms.Form): username = forms.CharField( min_length=10, label="用户名", initial="hewm" # 设置默认值方法 ) pwd = forms.CharField(min_length=10, label="密码")
error_messages
重写错误信息。
class LoginForm(forms.Form): username = forms.CharField( min_length=10, label="用户名", initial="rum", # 重写错误提示信息 error_messages={ "required": "不能为空", "invalid": "格式错误", "min_length": "用户名最短10位" } ) pwd = forms.CharField(min_length=10, label="密码")password
class LoginForm(forms.Form): ... pwd = forms.CharField( min_length=10, label="密码", # 密文方法 参数attrs：样式类 render_value=验证失败是否回填
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=10, label="用户名", initial="rum", error_messages={ "required": "不能为空", "invalid": "格式错误", "min_length": "用户名最短10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, "乒乓球"), ), 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 Formfrom django.forms import widgetsfrom django.forms import fields class MyForm(Form): user = fields.ChoiceField( # choices=((1, '上海'), (2, '北京'),), initial=2, widget=widgets.Select ) # 初始化init方法 （执行时间为类实例化时执行） 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 formsfrom django.forms import fieldsfrom 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())
内置字段
Field required=True, 是否允许为空 widget=None, HTML插件 label=None, 用于生成Label标签或显示内容 initial=None, 初始值 help_text='', 帮助信息(在标签旁边显示) error_messages=None, 错误信息 {'required': '不能为空', 'invalid': '格式错误'} show_hidden_initial=False, 是否在当前插件后面再加一个隐藏的且具有默认值的插件（可用于检验两次输入是否一直） validators=[], 自定义验证规则 localize=False, 是否支持本地化 disabled=False, 是否可以编辑 label_suffix=None Label内容后缀 CharField(Field) max_length=None, 最大长度 min_length=None, 最小长度 strip=True 是否移除用户输入空白 IntegerField(Field) max_value=None, 最大值 min_value=None, 最小值 FloatField(IntegerField) ... DecimalField(IntegerField) max_value=None, 最大值 min_value=None, 最小值 max_digits=None, 总长度 decimal_places=None, 小数位长度 BaseTemporalField(Field) input_formats=None 时间格式化 DateField(BaseTemporalField) 格式：2015-09-01TimeField(BaseTemporalField) 格式：11:12DateTimeField(BaseTemporalField)格式：2015-09-01 11:12 DurationField(Field) 时间间隔：%d %H:%M:%S.%f ... RegexField(CharField) regex, 自定制正则表达式 max_length=None, 最大长度 min_length=None, 最小长度 error_message=None, 忽略，错误信息使用 error_messages={'invalid': '...'} EmailField(CharField) ... FileField(Field) allow_empty_file=False 是否允许空文件 ImageField(FileField) ... 注：需要PIL模块，pip3 install Pillow 以上两个字典使用时，需要注意两点： - form表单中 enctype="multipart/form-data" - view函数中 obj = MyForm(request.POST, request.FILES) URLField(Field) ... BooleanField(Field) ... NullBooleanField(BooleanField) ... ChoiceField(Field) ... choices=(), 选项，如：choices = ((0,'上海'),(1,'北京'),) required=True, 是否必填 widget=None, 插件，默认select插件 label=None, Label内容 initial=None, 初始值 help_text='', 帮助提示 ModelChoiceField(ChoiceField) ... django.forms.models.ModelChoiceField queryset, # 查询数据库中的数据 empty_label="---------", # 默认空显示内容 to_field_name=None, # HTML中value的值对应的字段 limit_choices_to=None # ModelForm中对queryset二次筛选 ModelMultipleChoiceField(ModelChoiceField) ... django.forms.models.ModelMultipleChoiceField TypedChoiceField(ChoiceField) coerce = lambda val: val 对选中的值进行一次转换 empty_value= '' 空值的默认值 MultipleChoiceField(ChoiceField) ... TypedMultipleChoiceField(MultipleChoiceField) coerce = lambda val: val 对选中的每一个值进行一次转换 empty_value= '' 空值的默认值 ComboField(Field) fields=() 使用多个验证，如下：即验证最大长度20，又验证邮箱格式 fields.ComboField(fields=[fields.CharField(max_length=20), fields.EmailField(),]) MultiValueField(Field) PS: 抽象类，子类中可以实现聚合多个字典去匹配一个值，要配合MultiWidget使用 SplitDateTimeField(MultiValueField) input_date_formats=None, 格式列表：['%Y--%m--%d', '%m%d/%Y', '%m/%d/%y'] input_time_formats=None 格式列表：['%H:%M:%S', '%H:%M:%S.%f', '%H:%M'] FilePathField(ChoiceField) 文件选项，目录下文件显示在页面中 path, 文件夹路径 match=None, 正则匹配 recursive=False, 递归下面的文件夹 allow_files=True, 允许文件 allow_folders=False, 允许文件夹 required=True, widget=None, label=None, initial=None, help_text='' GenericIPAddressField protocol='both', both,ipv4,ipv6支持的IP格式 unpack_ipv4=False 解析ipv4地址，如果是::ffff:192.0.2.1时候，可解析为192.0.2.1， PS：protocol必须为both才能启用 SlugField(CharField) 数字，字母，下划线，减号（连字符） ... UUIDField(CharField) uuid类型Django form内置字段校验方式一：
from django.forms import Formfrom django.forms import widgetsfrom django.forms import fieldsfrom 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 refrom django.forms import Formfrom django.forms import widgetsfrom django.forms import fieldsfrom 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'}))补充进阶应用Bootstrap样式
<!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>批量添加样式
可通过重写form类的init方法来实现。
class LoginForm(forms.Form): username = forms.CharField( min_length=10, 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10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' })源码简易剖析views.py文件
def register(request): if request.method == "POST": res = {"user": None, "error_dict": None} form = RegForm(request.POST) # 存储验证通过的信息.is_valid()（源码剖析开始点） if form.is_valid(): user = form.cleaned_data.get("user") pwd = form.cleaned_data.get("pwd") email = form.cleaned_data.get("email") avatar = request.FILES.get("avatar") print(user,pwd,email,avatar) if avatar: user = UserInfo.objects.create_user(username=user, password=pwd, email=email, avatar=avatar) else: user = UserInfo.objects.create_user(username=user, password=pwd, email=email) res["user"] = user.username else: print(form.errors) res["error_dict"] = form.errors return JsonResponse(res) form = RegForm() return render(request, 'register.html', locals())点击进入forms.py文件
def is_valid(self): """ Returns True if the form has no errors. Otherwise, False. If errors are being ignored, returns False. """ # 含义：返回布尔值，只要有数据并且没有错误信息就返回True return self.is_bound and not self.errors
点击self.errors进入forms.py文件中
# 静态方法@property def errors(self): "Returns an ErrorDict for the data provided for the form" # 判断self._errors是否为空 if self._errors is None: self.full_clean() return self._errors
点击._errors进入forms.py文件中
def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None, initial=None, error_class=ErrorList, label_suffix=None, empty_permitted=False, field_order=None, use_required_attribute=None, renderer=None): self.is_bound = data is not None or files is not None self.data = data or {} self.files = files or {} self.auto_id = auto_id if prefix is not None: self.prefix = prefix self.initial = initial or {} self.error_class = error_class # Translators: This is the default suffix added to form field labels self.label_suffix = label_suffix if label_suffix is not None else _(':') self.empty_permitted = empty_permitted # 默认值为None self._errors = None # Stores the errors after clean() has been called. # The base_fields class attribute is the *class-wide* definition of # fields. Because a particular *instance* of the class might want to # alter self.fields, we create self.fields here by copying base_fields. # Instances should always modify self.fields; they should not modify # self.base_fields. self.fields = copy.deepcopy(self.base_fields) self._bound_fields_cache = {} self.order_fields(self.field_order if field_order is None else field_order)返回def errors(self)
@property def errors(self): "Returns an ErrorDict for the data provided for the form" if self._errors is None: self.full_clean() # 这个方法才是真正帮忙执行效验操作 return self._errors
点击full_clean方法
def full_clean(self): """ Cleans all of self.data and populates self._errors and self.cleaned_data. """ self._errors = ErrorDict() # 定义一个保存错误信息字典 if not self.is_bound: # Stop further processing. return self.cleaned_data = {} # If the form is permitted to be empty, and none of the form data has # changed from the initial data, short circuit any validation. if self.empty_permitted and not self.has_changed(): return self._clean_fields() self._clean_form() self._post_clean()点击self._clean_fields()进入
def _clean_fields(self): for name, field in self.fields.items(): # self.fields：类似一个字典 #for name, field in self.fields.items():解释分别获取self.fields的键和值分别赋值给 name, field # value_from_datadict() gets the data from the data dictionaries. # Each widget type knows how to retrieve its own data, because some # widgets split data over several HTML fields. if field.disabled: value = self.get_initial_for_field(field, name) else: value = field.widget.value_from_datadict(self.data, self.files, self.add_prefix(name)) try: if isinstance(field, FileField): # 如果是文件字段 initial = self.get_initial_for_field(field, name) value = field.clean(value, initial) else: # field.clean(value) 之后Dbug运行检查，为循环判断错误 value = field.clean(value) self.cleaned_data[name] = value if hasattr(self, 'clean_%s' % name): value = getattr(self, 'clean_%s' % name)() self.cleaned_data[name] = value except ValidationError as e: self.add_error(name, e)
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