Python学习教程_Python学习路线：Day45-55/04表单的应用

我们接着上次的Python100天学习教程跟大家更新：

Python学习教程_Python学习路线：表单的应用

我们继续来完成之前跟大家讲的Python100天项目，实现“用户注册”和“用户登录”的功能，并限制只有登录的用户才能为老师投票。Django框架中提供了对表单的封装，而且提供了多种不同的使用方式。

首先添加用户模型。

class User(models.Model):    """用户"""
    no = models.AutoField(primary_key=True, verbose_name='编号')
    username = models.CharField(max_length=20, unique=True, verbose_name='用户名')
    password = models.CharField(max_length=32, verbose_name='密码')
    regdate = models.DateTimeField(auto_now_add=True, verbose_name='注册时间')    class Meta:
        db_table = 'tb_user'
        verbose_name_plural = '用户'

通过生成迁移和执行迁移操作，在数据库中创建对应的用户表。

python manage.py makemigrations 应用名
python manage.py migrate

定制一个非常简单的注册模板页面。




    
    用户注册
    


    用户注册
    
    {{ hint }}
    
        {% csrf_token %}
        
            用户名：

USERNAME_PATTERN = re.compile(r'\w{4,20}')class RegisterForm(forms.ModelForm): repassword = forms.CharField(min_length=8, max_length=20) def clean_username(self): username = self.cleaned_data['username'] if not USERNAME_PATTERN.fullmatch(username): raise ValidationError('用户名由字母、数字和下划线构成且长度为4-20个字符') return username def clean_password(self): password = self.cleaned_data['password'] if len(password) < 8 or len(password) > 20: raise ValidationError('无效的密码，密码长度为8-20个字符') return to_md5_hex(self.cleaned_data['password']) def clean_repassword(self): repassword = to_md5_hex(self.cleaned_data['repassword']) if repassword != self.cleaned_data['password']: raise ValidationError('密码和确认密码不一致') return repassword class Meta: model = User exclude = ('no', 'regdate')

def register(request): page, hint = 'register.html', '' if request.method == 'POST': form = RegisterForm(request.POST) if form.is_valid(): form.save() page = 'login.html' hint = '注册成功，请登录' else: hint = '请输入有效的注册信息' return render(request, page, {'hint': hint})

from django.contrib import adminfrom django.urls import pathfrom vote import views urlpatterns = [ path('', views.show_subjects), path('captcha/', views.get_captcha), path('teachers/', views.show_teachers), path('prise/', views.praise_or_criticize), path('criticize/', views.praise_or_criticize), path('login/', views.login, name='login'), path('register/', views.register, name='register'), path('admin/', admin.site.urls), ]

用户登录

{% csrf_token %} 用户名：

"""图片验证码"""import osimport randomfrom io import BytesIOfrom PIL import Imagefrom PIL import ImageFilterfrom PIL.ImageDraw import Drawfrom PIL.ImageFont import truetypeclass Bezier(object): """贝塞尔曲线""" def __init__(self): self.tsequence = tuple([t / 20.0 for t in range(21)]) self.beziers = {} def make_bezier(self, n): """绘制贝塞尔曲线""" try: return self.beziers[n] except KeyError: combinations = pascal_row(n - 1) result = [] for t in self.tsequence: tpowers = (t ** i for i in range(n)) upowers = ((1 - t) ** i for i in range(n - 1, -1, -1)) coefs = [c * a * b for c, a, b in zip(combinations, tpowers, upowers)] result.append(coefs) self.beziers[n] = result return resultclass Captcha(object): """验证码""" def __init__(self, width, height, fonts=None, color=None): self._image = None self._fonts = fonts if fonts else \ [os.path.join(os.path.dirname(__file__), 'fonts', font) for font in ['Action.ttf', 'Silom.ttf', 'Verdana.ttf']] self._color = color if color else random_color(0, 200, random.randint(220, 255)) self._width, self._height = width, height @classmethod def instance(cls, width=200, height=75): if not hasattr(Captcha, "_instance"): cls._instance = cls(width, height) return cls._instance def background(self): """绘制背景""" Draw(self._image).rectangle([(0, 0), self._image.size], fill=random_color(230, 255)) def smooth(self): """平滑图像""" return self._image.filter(ImageFilter.SMOOTH) def curve(self, width=4, number=6, color=None): """绘制曲线""" dx, height = self._image.size dx /= number path = [(dx * i, random.randint(0, height)) for i in range(1, number)] bcoefs = Bezier().make_bezier(number - 1) points = [] for coefs in bcoefs: points.append(tuple(sum([coef * p for coef, p in zip(coefs, ps)]) for ps in zip(*path))) Draw(self._image).line(points, fill=color if color else self._color, width=width) def noise(self, number=62, level=2, color=None): """绘制扰码""" width, height = self._image.size dx, dy = width / 10, height / 10 width, height = width - dx, height - dy draw = Draw(self._image) for i in range(number): x = int(random.uniform(dx, width)) y = int(random.uniform(dy, height)) draw.line(((x, y), (x + level, y)), fill=color if color else self._color, width=level) def text(self, captcha_text, fonts, font_sizes=None, drawings=None, squeeze_factor=0.75, color=None): """绘制文本""" color = color if color else self._color fonts = tuple([truetype(name, size) for name in fonts for size in font_sizes or (65, 70, 75)]) draw = Draw(self._image) char_images = [] for c in captcha_text: font = random.choice(fonts) c_width, c_height = draw.textsize(c, font=font) char_image = Image.new('RGB', (c_width, c_height), (0, 0, 0)) char_draw = Draw(char_image) char_draw.text((0, 0), c, font=font, fill=color) char_image = char_image.crop(char_image.getbbox()) for drawing in drawings: d = getattr(self, drawing) char_image = d(char_image) char_images.append(char_image) width, height = self._image.size offset = int((width - sum(int(i.size[0] * squeeze_factor) for i in char_images[:-1]) - char_images[-1].size[0]) / 2) for char_image in char_images: c_width, c_height = char_image.size mask = char_image.convert('L').point(lambda i: i * 1.97) self._image.paste(char_image, (offset, int((height - c_height) / 2)), mask) offset += int(c_width * squeeze_factor) @staticmethod def warp(image, dx_factor=0.3, dy_factor=0.3): """图像扭曲""" width, height = image.size dx = width * dx_factor dy = height * dy_factor x1 = int(random.uniform(-dx, dx)) y1 = int(random.uniform(-dy, dy)) x2 = int(random.uniform(-dx, dx)) y2 = int(random.uniform(-dy, dy)) warp_image = Image.new( 'RGB', (width + abs(x1) + abs(x2), height + abs(y1) + abs(y2))) warp_image.paste(image, (abs(x1), abs(y1))) width2, height2 = warp_image.size return warp_image.transform( (width, height), Image.QUAD, (x1, y1, -x1, height2 - y2, width2 + x2, height2 + y2, width2 - x2, -y1)) @staticmethod def offset(image, dx_factor=0.1, dy_factor=0.2): """图像偏移""" width, height = image.size dx = int(random.random() * width * dx_factor) dy = int(random.random() * height * dy_factor) offset_image = Image.new('RGB', (width + dx, height + dy)) offset_image.paste(image, (dx, dy)) return offset_image @staticmethod def rotate(image, angle=25): """图像旋转""" return image.rotate(random.uniform(-angle, angle), Image.BILINEAR, expand=1) def generate(self, captcha_text='', fmt='PNG'): """生成验证码(文字和图片)""" self._image = Image.new('RGB', (self._width, self._height), (255, 255, 255)) self.background() self.text(captcha_text, self._fonts, drawings=['warp', 'rotate', 'offset']) self.curve(), self.noise(), self.smooth() image_bytes = BytesIO() self._image.save(image_bytes, format=fmt) return image_bytes.getvalue()def pascal_row(n=0): """生成Pascal三角第n行""" result = [1] x, numerator = 1, n for denominator in range(1, n // 2 + 1): x *= numerator x /= denominator result.append(x) numerator -= 1 if n & 1 == 0: result.extend(reversed(result[:-1])) else: result.extend(reversed(result)) return resultdef random_color(start=0, end=255, opacity=255): """获得随机颜色""" red = random.randint(start, end) green = random.randint(start, end) blue = random.randint(start, end) if opacity is None: return red, green, blue return red, green, blue, opacity

ALL_CHARS = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'def get_captcha_text(length=4): selected_chars = random.choices(ALL_CHARS, k=length) return ''.join(selected_chars)def get_captcha(request): """获得验证码""" captcha_text = get_captcha_text() image = Captcha.instance().generate(captcha_text) return HttpResponse(image, content_type='image/png')

class LoginForm(forms.Form): username = forms.CharField(min_length=4, max_length=20) password = forms.CharField(min_length=8, max_length=20) captcha = forms.CharField(min_length=4, max_length=4) def clean_username(self): username = self.cleaned_data['username'] if not USERNAME_PATTERN.fullmatch(username): raise ValidationError('无效的用户名') return username def clean_password(self): return to_md5_hex(self.cleaned_data['password'])

def login(request): hint = '' if request.method == 'POST': form = LoginForm(request.POST) if form.is_valid(): username = form.cleaned_data['username'] password = form.cleaned_data['password'] user = User.objects.filter(username=username, password=password).first() if user: return redirect('/') else: hint = '用户名或密码错误' else: hint = '请输入有效的登录信息' return render(request, 'login.html', {'hint': hint})