Python之路【第二十一篇】：Django之Form组件

Django之Form组件

 

Django的Form主要具有一下几大功能：

• 生成HTML标签
• 验证用户数据（显示错误信息）
• HTML Form提交保留上次提交数据
• 初始化页面显示内容

小试牛刀

1、创建Form类

from  django.forms  import  Form
from  django.forms  import  widgets
from  django.forms  import  fields

class  MyForm(Form):
    user  =  fields.CharField(
        widget = widgets.TextInput(attrs = { 'id' :  'i1' ,  'class' :  'c1' })
    )

    gender  =  fields.ChoiceField(
        choices = (( 1 ,  '男' ), ( 2 ,  '女' ),),
        initial = 2 ,
        widget = widgets.RadioSelect
    )

    city  =  fields.CharField(
        initial = 2 ,
        widget = widgets.Select(choices = (( 1 , '上海' ),( 2 , '北京' ),))
    )

    pwd  =  fields.CharField(
        widget = widgets.PasswordInput(attrs = { 'class' :  'c1' }, render_value = True )
    )

2、View函数处理

from  django.shortcuts  import  render, redirect
from  .forms  import  MyForm


def  index(request):
    if  request.method  = =  "GET" :
        obj  =  MyForm()
        return  render(request,  'index.html' , { 'form' : obj})
    elif  request.method  = =  "POST" :
        obj  =  MyForm(request.POST, request.FILES)
        if  obj.is_valid():
            values  =  obj.clean()
            print (values)
        else :
            errors  =  obj.errors
            print (errors)
        return  render(request,  'index.html' , { 'form' : obj})
    else :
        return  redirect( 'http://www.google.com' )

3、生成HTML

= "/"  method = "POST"  enctype = "multipart/form-data" >
    {{ form.user }} {{ form.user.errors }}< / p>
    {{ form.gender }} {{ form.gender.errors }}< / p>
    {{ form.city }} {{ form.city.errors }}< / p>
    {{ form.pwd }} {{ form.pwd.errors }}< / p>
    < input  type = "submit" / >
< / form>

    
        {% csrf_token %}
        
            {{ form.xxoo.label }}
            {{ form.xxoo.id_for_label }}
            {{ form.xxoo.label_tag }}
            {{ form.xxoo.errors }}
            
{{ form.user }} {{ form.user.errors }}
            
    

Form类

创建Form类时，主要涉及到 【字段】 和 【插件】，字段用于对用户请求数据的验证，插件用于自动生成HTML;

1、Django内置字段如下：

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

        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
            ...

注：UUID是根据MAC以及当前时间等创建的不重复的随机字符串

   >>> import uuid

    # make a UUID based on the host ID and current time
    >>> uuid.uuid1()    # doctest: +SKIP
    UUID('a8098c1a-f86e-11da-bd1a-00112444be1e')

    # make a UUID using an MD5 hash of a namespace UUID and a name
    >>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org')
    UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e')

    # make a random UUID
    >>> uuid.uuid4()    # doctest: +SKIP
    UUID('16fd2706-8baf-433b-82eb-8c7fada847da')

    # make a UUID using a SHA-1 hash of a namespace UUID and a name
    >>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org')
    UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d')

    # make a UUID from a string of hex digits (braces and hyphens ignored)
    >>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}')

    # convert a UUID to a string of hex digits in standard form
    >>> str(x)
    '00010203-0405-0607-0809-0a0b0c0d0e0f'

    # get the raw 16 bytes of the UUID
    >>> x.bytes
    b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f'

    # make a UUID from a 16-byte string
    >>> uuid.UUID(bytes=x.bytes)
    UUID('00010203-0405-0607-0809-0a0b0c0d0e0f')

2、Django内置插件：

TextInput( Input )
NumberInput(TextInput)
EmailInput(TextInput)
URLInput(TextInput)
PasswordInput(TextInput)
HiddenInput(TextInput)
Textarea(Widget)
DateInput(DateTimeBaseInput)
DateTimeInput(DateTimeBaseInput)
TimeInput(DateTimeBaseInput)
CheckboxInput
Select
NullBooleanSelect
SelectMultiple
RadioSelect
CheckboxSelectMultiple
FileInput
ClearableFileInput
MultipleHiddenInput
SplitDateTimeWidget
SplitHiddenDateTimeWidget
SelectDateWidget

常用选择插件

# 单radio，值为字符串
# user = fields.CharField(
#     initial=2,
#     widget=widgets.RadioSelect(choices=((1,'上海'),(2,'北京'),))
# )

# 单radio，值为字符串
# user = fields.ChoiceField(
#     choices=((1, '上海'), (2, '北京'),),
#     initial=2,
#     widget=widgets.RadioSelect
# )

# 单select，值为字符串
# user = fields.CharField(
#     initial=2,
#     widget=widgets.Select(choices=((1,'上海'),(2,'北京'),))
# )

# 单select，值为字符串
# user = fields.ChoiceField(
#     choices=((1, '上海'), (2, '北京'),),
#     initial=2,
#     widget=widgets.Select
# )

# 多选select，值为列表
# user = fields.MultipleChoiceField(
#     choices=((1,'上海'),(2,'北京'),),
#     initial=[1,],
#     widget=widgets.SelectMultiple
# )


# 单checkbox
# user = fields.CharField(
#     widget=widgets.CheckboxInput()
# )


# 多选checkbox,值为列表
# user = fields.MultipleChoiceField(
#     initial=[2, ],
#     choices=((1, '上海'), (2, '北京'),),
#     widget=widgets.CheckboxSelectMultiple
# )

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  Form
from  django.forms  import  widgets
from  django.forms  import  fields
from  django.core.validators  import  RegexValidator

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 ().value_list( 'id' , 'caption' )

方式二：

使用django提供的ModelChoiceField和ModelMultipleChoiceField字段来实现

from  django  import  forms
from  django.forms  import  fields
from  django.forms  import  widgets
from  django.forms  import  models as form_model
from  django.core.exceptions  import  ValidationError
from  django.core.validators  import  RegexValidator

class  FInfo(forms.Form):
    authors  =  form_model.ModelMultipleChoiceField(queryset = models.NNewType.objects. all ())
    # authors = form_model.ModelChoiceField(queryset=models.NNewType.objects.all())

自定义验证规则

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]+$' ,  '请输入数字' ), RegexValidator(r '^159[0-9]+$' ,  '数字必须以159开头' )],
    )

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' }))

方法三：自定义方法

from  django  import  forms
    from  django.forms  import  fields
    from  django.forms  import  widgets
    from  django.core.exceptions  import  ValidationError
    from  django.core.validators  import  RegexValidator

    class  FInfo(forms.Form):
        username  =  fields.CharField(max_length = 5 ,
                                    validators = [RegexValidator(r '^[0-9]+$' ,  'Enter a valid extension.' ,  'invalid' )], )
        email  =  fields.EmailField()

        def  clean_username( self ):
            """
            Form中字段中定义的格式匹配完之后，执行此方法进行验证
            :return:
            """
            value  =  self .cleaned_data[ 'username' ]
            if  "666"  in  value:
                raise  ValidationError( '666已经被玩烂了...' ,  'invalid' )
            return  value

方式四：同时生成多个标签进行验证

from  django.forms  import  Form
from  django.forms  import  widgets
from  django.forms  import  fields

from  django.core.validators  import  RegexValidator


############## 自定义字段 ##############
class  PhoneField(fields.MultiValueField):
    def  __init__( self ,  * args,  * * kwargs):
        # Define one message for all fields.
        error_messages  =  {
            'incomplete' :  'Enter a country calling code and a phone number.' ,
        }
        # Or define a different message for each field.
        f  =  (
            fields.CharField(
                error_messages = { 'incomplete' :  'Enter a country calling code.' },
                validators = [
                    RegexValidator(r '^[0-9]+$' ,  'Enter a valid country calling code.' ),
                ],
            ),
            fields.CharField(
                error_messages = { 'incomplete' :  'Enter a phone number.' },
                validators = [RegexValidator(r '^[0-9]+$' ,  'Enter a valid phone number.' )],
            ),
            fields.CharField(
                validators = [RegexValidator(r '^[0-9]+$' ,  'Enter a valid extension.' )],
                required = False ,
            ),
        )
        super (PhoneField,  self ).__init__(error_messages = error_messages, fields = f, require_all_fields = False ,  * args,
                                         * * kwargs)

    def  compress( self , data_list):
        """
        当用户验证都通过后，该值返回给用户
        :param data_list:
        :return:
        """
        return  data_list

############## 自定义插件 ##############
class  SplitPhoneWidget(widgets.MultiWidget):
    def  __init__( self ):
        ws  =  (
            widgets.TextInput(),
            widgets.TextInput(),
            widgets.TextInput(),
        )
        super (SplitPhoneWidget,  self ).__init__(ws)

    def  decompress( self , value):
        """
        处理初始值，当初始值initial不是列表时，调用该方法
        :param value:
        :return:
        """
        if  value:
            return  value.split( ',' )
        return  [ None ,  None ,  None ]

初始化数据

在Web应用程序中开发编写功能时，时常用到获取数据库中的数据并将值初始化在HTML中的标签上。

1、Form

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()

    city  =  fields.ChoiceField(
        choices = (( 1 ,  '上海' ), ( 2 ,  '北京' ),),
        widget = widgets.Select
    )

2、Views

from  django.shortcuts  import  render, redirect
from  .forms  import  MyForm


def  index(request):
    if  request.method  = =  "GET" :
        values  =  { 'user' :  'root' ,  'city' :  2 }
        obj  =  MyForm(values)

        return  render(request,  'index.html' , { 'form' : obj})
    elif  request.method  = =  "POST" :
        return  redirect( 'http://www.google.com' )
    else :
        return  redirect( 'http://www.google.com' )

3、HTML

= "POST"  enctype = "multipart/form-data" >
    { %  csrf_token  % }
    {{ form.user }} {{ form.user.errors }}< / p>
    {{ form.city }} {{ form.city.errors }}< / p>

    < input  type = "submit" / >
< / form>

 

转载于:https://www.cnblogs.com/weiman3389/p/6225306.html