Django 框架之Form组件

Posted 2020-10-29 思考与践行

1. Django的Form主要具有以下几大功能:

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

2. 第一个案例:

# 第一步: 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\':\'name\', \'class\':\'cs\'})
    )

    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\':\'cs\'}, render_value = True)
    )

# 第二步: 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\')

# 第四步: 生成HTML
<form action="/" method="POST" enctype="multipart/form-data">
    <p>{{ form.user }} {{ form.user.errors }}</p>
    <p>{{ form.gender}} {{ form.gender.errors }}</p>
    <p>{{ form.city }} {{ form.city.errors }}</p>
    <p>{{ form.pwd }} {{ form.pwd.errors }}</p>
    <input typy="submit" value="提交"/>
</form>

# PS: 其他标签
<form method="POST" enctype="multipart/form-data">
    {% csrf_token %}

        {{ form.xxoo.label }}
        {{ form.xxoo.id_for_label }}
        {{ form.xxoo.label_tag }}
        {{ form.xxoo.errors }}
        <p>{{ form.user }} {{ form.user.errors }}</p>
        <input type="submit" value="提交"/>
</form>

3. 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;

3.1 Django 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_message=None,         错误信息 {\'require\': \'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
    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字符


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: 2018-04-02
TimeField(BaseTemporalField)        格式: 11:12
DateTimeField(BaseTemporalField)    格式: 2018-04-02 11:20


DurationField(Field)            时间间隔: %d %H:%M:%S.%f
    ...


RegexField(CharField)
    regex,                      自定义正则表达式
    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)
    ...
    # 备注: 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)
    ...         
    queryset,                   查询数据库中的数据
    empty_label="=========="    默认空,显示的内容
    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)
    ...


TypeChoiceField(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)
    ...

TypeMultipleChoiceField(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,

# 示例: 既验证最大长度20, 又验证邮箱格式
#   fields.ComboField(fields=[fields.CharField(max_length=20), fields.EmailField(),])


MultiValueField(Field)
    # 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\']


# 文件选项, 目录是下文件显示在页面中
FilePathField(ChoiceField)
    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,
                            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
    ...

3.2 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

3.2.1 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\'),(1, \'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:
#   通过django提供的ModelChoiceField和ModelMultipleChoiceField字段来实现
form 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())

4. 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_message={\'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\'})


# 方式三: 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
        value = self.cleaned_data[\'username\']
        if \'999\' in value:
            raise ValidationError(\'999 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):
    # 所有字段通用错误信息
    def __init__(self, *args, **kwargs):
        error_messages = {
            \'incomplete\': \'Enter a country calling code and a phone number.\'
        }

        # 各个字段的自定义错误信息
        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
        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
        if value:
            return value.split(\',\')
        return [None, None, None]

5. 初始化数据

• 在Web应用程序中,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

# 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
    )


# 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\')


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

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

参考资料:

• Python 全栈
• Django之Form组件