Django的Forms组件主要有以下几大功能：
- 页面初始化，生成HTML标签
- 校验用户数据（显示错误信息）
- HTML Form提交保留上次提交数据
一、小试牛刀
1、定义Form类
from django import forms
class EmpForm(forms.Form):
name = forms.CharField(min_length=5, label="姓名", error_messages={"required": "该字段不能为空!",
"min_length": "用户名太短。"})
age = forms.IntegerField(label="年龄")
salary = forms.DecimalField(max_digits=5, decimal_places=2, label="工资")
class Emp(models.Model): name = models.CharField(max_length=32) age = models.IntegerField() salary = models.DecimalField(max_digits=8, decimal_places=2)
2、设计url与视图对应关系
from django.contrib import admin from django.urls import path from app01 import views urlpatterns = [ path('admin/', admin.site.urls), path('index/', views.index), path('add_emp/', views.add_emp), ]
3、视图函数
from django.shortcuts import render,redirect from app01 import models # Create your views here. from django.http.response import HttpResponse def index(request): return HttpResponse("okok!") from app01.MyForms import EmpForm def add_emp(request): if request.method == "GET": form = EmpForm() # 初始化form对象 return render(request, "add_emp.html", {"form":form}) #传送一个实例对象 else: form = EmpForm(request.POST) # 将数据传给form对象 if form.is_valid(): # 进行校验 data = form.cleaned_data # 校验通过的数据，字典 print(data)#{'name': 'alex01', 'age': 12, 'salary': Decimal('21')} models.Emp.objects.create(**data) return redirect("/index/") else: # 校验失败 print(form.errors) #<ul class="errorlist"><li>name<ul class="errorlist"><li>用户名太短。</li></ul></li><li>age<ul class="errorlist"><li>This field is required.</li></ul></li><li>salary<ul class="errorlist"><li>This field is required.</li></ul></li></ul> '''<ul class="errorlist"> <li> name <ul class="errorlist"> <li>用户名太短。</li> 可能会有多个错误 ... </ul> </li> <li>age<ul class="errorlist"><li>This field is required.</li></ul></li> <li>salary<ul class="errorlist"><li>This field is required.</li></ul></li> </ul>''' return render(request, "add_emp.html", {"form": form}) #传送一个带错误信息实例对象
4、模板文件
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title></title> </head> <body> <h3>添加员工</h3> {#1、自己手动写HTML页面#} {#<form action="" method="post">#} {# <p>姓名：<input type="text" name="name"></p>#} {# <p>年龄：<input type="text" name="age"></p>#} {# <p>工资：<input type="text" name="salary"></p>#} {# <input type="submit">#} {#</form>#} {#2、通过form对象的as_p方法实现#} {#<form action="" method="post" novalidate>#} {# {% csrf_token %}#} {# {{ form.as_p }}#} {# <input type="submit">#} {#</form>#} </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <form action="" method="post" novalidate> <!--novalidate novalidate 属性规定当提交表单时不对其进行验证。如果使用该属性，则表单（浏览器）不会验证表单的输入。--> {% csrf_token %} <div> <label for="id_{{ form.name.name }}">姓名</label> <!--form.name.name等价于表单类的字段名 等价于 name age salary ... --> {{ form.name }} <span>{{ form.name.errors.0 }}<!--form.name.errors.0 表单类可能定义了多个错误信息 先显示第一个 解决完 --></span> </div> <div> <label for="id_{{ form.age.name }}">年龄</label> {{ form.age }} <span>{{ form.age.errors.0 }}</span> </div> <div> <label for="id_salary">工资</label> {{ form.salary }} <span>{{ form.salary.errors.0 }}</span> </div> <input type="submit"> </form> <!--以下为浏览器显示的页面--> <!--<form action="" method="post" novalidate>--> <!--<input type="hidden" name="csrfmiddlewaretoken" value="oVa3cSt17v5ie9bQBWo3MEBiv32zysmCAvY2QMCGHk3aDyaMFPhnR8ikIniQoA0H">--> <!--<div>--> <!--<label for="id_name">姓名</label>--> <!--<input type="text" name="name" value="alex" minlength="5" required id="id_name"> <span>用户名太短。</span>--> <!--</div>--> <!--<div>--> <!--<label for="id_age">年龄</label>--> <!--<input type="number" name="age" required id="id_age"> <span>This field is required.</span>--> <!--</div>--> <!--<div>--> <!--<label for="id_salary">工资</label>--> <!--<input type="number" name="salary" step="0.01" required id="id_salary"> <span>This field is required.</span>--> <!--</div>--> <!--<input type="submit">--> <!--</form>--> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <form action="" method="post" novalidate> {% csrf_token %} {% for field in form %} <!-- 遍历form表单类所有的字段信息 field 相当于 第三种方式的 form.name/form.age/form.salary--> <div> <label for="id_{{ field.name }}">{{ field.label }}</label> <!--发现：name = forms.CharField(min_length=5, label="姓名", error_messages={"required": "该字段不能为空!","min_length": "用户名太短。"}) 表单类定义的字段属性 字段都可以在前端调用 field.label --> {{ field }} <span>{{ field.errors.0 }}</span> <!-- field.errors.0 跟这个error_messages={"required": "该字段不能为空!","min_length": "用户名太短。"} 有关联--> </div> {% endfor %} <input type="submit"> </form> </body> </html>
附：Django内置的字段及属性
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：2015-09-01 TimeField(BaseTemporalField) 格式：11:12 DateTimeField(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 ...
二、局部钩子和全局钩子
1、定义Form类
from django import forms from django.core.exceptions import ValidationError #导包 from django.core.exceptions import ValidationError from app01 import models class EmpForm(forms.Form): name = forms.CharField(min_length=5, label="姓名", error_messages={"required": "该字段不能为空!", "min_length": "用户名太短。"}) age = forms.IntegerField(label="年龄") salary = forms.DecimalField(max_digits=5, decimal_places=2, label="工资") r_salary = forms.DecimalField(max_digits=5, decimal_places=2, label="请确认工资") # 局部钩子 def clean_name(self): # 名称不能随便起，必须要clean_类属性名称 val = self.cleaned_data.get("name") if val.isdigit(): raise ValidationError("用户名不能全是数字。") elif models.Emp.objects.filter(name=val): raise ValidationError("用户名已存在。") else: return val def clean(self): salary = self.cleaned_data.get("salary") r_salary = self.cleaned_data.get("r_salary") if salary != r_salary: raise ValidationError("工资输入有误。") else: return self.cleaned_data
from django import forms
from django.core.exceptions import ValidationError
from app01 import models
class EmpForm(forms.Form):
name = forms.CharField(min_length=5, label="姓名", error_messages={"required": "该字段不能为空!",
"min_length": "用户名太短。"})
age = forms.IntegerField(label="年龄")
salary = forms.DecimalField(max_digits=5, decimal_places=2, label="工资")
r_salary = forms.DecimalField(max_digits=5, decimal_places=2, label="请再输入工资")
def clean_name(self): # 局部钩子
val = self.cleaned_data.get("name")
if val.isdigit():
raise ValidationError("用户名不能是纯数字")
elif models.Emp.objects.filter(name=val):
raise ValidationError("用户名已存在！")
else:
return val
def clean(self): # 全局钩子 确认两次输入的工资是否一致。
val = self.cleaned_data.get("salary")
r_val = self.cleaned_data.get("r_salary")
if val == r_val:
return self.cleaned_data
else:
raise ValidationError("请确认工资是否一致。")
2、视图函数
from django.shortcuts import render,redirect from app01 import models # Create your views here. from django.http.response import HttpResponse def index(request): return HttpResponse("okok!") from app01.MyForms import EmpForm def add_emp(request): if request.method == "POST": # data = request.POST.get() form = EmpForm(request.POST) if form.is_valid(): print(1111,form.cleaned_data) models.Emp.objects.create(**form.cleaned_data) else: print(form.errors)#<ul class="errorlist"><li>name<ul class="errorlist"><li>用户名太短。</li></ul></li><li>__all__<ul class="errorlist nonfield"><li>工资输入有误。</li></ul></li></ul> clear_errors = form.errors.get("__all__") # 获取全局钩子错误信息 return render(request, "add_emp.html", {"form": form, "clear_errors": clear_errors}) else: form = EmpForm() return render(request, "add_emp.html", {"form": form}) '''源码解析 MyForms.py:from django import forms 《--- views.py:from app01.MyForms import EmpForm 第一步：form = EmpForm() 生成一个EmpForm表单类对象（该类继承了from django import forms里面的forms.Form类） 第二步：POST请求接受客户的请求数据 进行验证 form = EmpForm(request.POST)---》form.is_valid() 1、 def is_valid(self): """Return True if the form has no errors, or False otherwise.""" return self.is_bound and not self.errors 2、 @property def errors(self): """Return an ErrorDict for the data provided for the form.""" if self._errors is None: self.full_clean() return self._errors 3、 def full_clean(self): """ Clean all of self.data and populate self._errors and self.cleaned_data. """ self._errors = ErrorDict() 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() 4、MyForms.py有自定义的局部钩子 就会调用 MyForms.py的局部钩子 def _clean_fields(self): for name, field in self.fields.items(): # 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): initial = self.get_initial_for_field(field, name) value = field.clean(value, initial) else: 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) 5、MyForms.py有自定义的全局钩子 就会调用 MyForms.py的全局钩子 def _clean_form(self): try: cleaned_data = self.clean() except ValidationError as e: self.add_error(None, e) else: if cleaned_data is not None: self.cleaned_data = cleaned_data '''
def add_emp(request):
if request.method == "GET":
form = EmpForm() # 初始化form对象
return render(request, "add_emp.html", {"form":form})
else:
form = EmpForm(request.POST) # 将数据传给form对象
if form.is_valid(): # 进行校验
data = form.cleaned_data
data.pop("r_salary")
models.Emp.objects.create(**data)
return redirect("/index/")
else: # 校验失败
clear_errors = form.errors.get("__all__") # 获取全局钩子错误信息
return render(request, "add_emp.html", {"form": form, "clear_errors": clear_errors})
3、模板文件
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <form action="" method="post" novalidate> {% csrf_token %} <div> <label for="id_{{ form.name.name }}">姓名</label> {{ form.name }} <span>{{ form.name.errors.0 }}</span> </div> <div> <label for="id_{{ form.age.name }}">年龄</label> {{ form.age }} <span>{{ form.age.errors.0 }}</span> </div> <div> <label for="id_salary">工资</label> {{ form.salary }} <span>{{ form.salary.errors.0 }}{{ clear_errors.0 }}</span> </div> <div> <label for="id_r_salary">请再输入工资</label> {{ form.r_salary }} <span>{{ form.r_salary.errors.0 }}{{ clear_errors.0 }}</span> </div> <input type="submit"> </form> </body> </html>
另一种方法导入app01/models模型类的数据，其它方法与上面一致
