【译】WTForms 2 中文入门教程(速成课程)

摘要：你打了个响指然后开始致力于你想写的棒极了的网络应用程序你写完一些页面最后你需要着手处理令人讨厌的任务处理和验证表单输入进入开始但是为什么我需要另一个框架呢好吧一些网络应用程序框架采用数据库模型和表单处理相结合的方法同时这对很基本的创建更新视

你打了个响指, 然后开始致力于你想写的棒极了的 Python 网络应用程序. 你写完一些页面, 最后你需要着手处理令人讨厌的任务：处理和验证表单输入. 进入（开始）WTForms.

但是, 为什么我需要另一个框架呢？好吧, 一些网络应用程序框架采用数据库模型和表单处理相结合的方法. 同时这对很基本的创建/更新视图函数是很方便的, 可能性是不是每个你需要的表单都能直接映射到一个数据库模型. 也许你已经使用通用的表单处理框架, 只是你想要定制这些表单域的 HTML 代码生成, 并且定义属于你的验证器.

使用 WTForms, 你能生成属于你的表单域的 HTML 代码, 此外我们允许你在模板中定制它. 这允许你维持独立的代码和展现, 并把这些凌乱的参数保留在 Python 代码之外. 因为我们争取松耦合, 同样的, 你应该可以在你喜欢的任意的模板引擎中这么做.

  
备注: 本人未过四级, 翻译水平有限, 欢迎指正.

安装 WTForms 最简单的方式是使用 easy_install 和 pip:

basheasy_install WTForms
# or
pip install WTForms

pythonfrom wtforms import Form, BooleanField, StringField, validators

class RegistrationForm(Form):
    username     = StringField("Username", [validators.Length(min=4, max=25)])
    email        = StringField("Email Address", [validators.Length(min=6, max=35)])
    accept_rules = BooleanField("I accept the site rules", [validators.InputRequired()])

pythonclass ProfileForm(Form):
    birthday  = DateTimeField("Your Birthday", format="%m/%d/%y")
    signature = TextAreaField("Forum Signature")

class AdminProfileForm(ProfileForm):
    username = StringField("Username", [validators.Length(max=40)])
    level    = IntegerField("User Level", [validators.NumberRange(min=0, max=10)])

pythondef register(request):
    form = RegistrationForm(request.POST)
    if request.method == "POST" and form.validate():
        user = User()
        user.username = form.username.data
        user.email = form.email.data
        user.save()
        redirect("register")
    return render_response("register.html", form=form)

pythondef edit_profile(request):
    user = request.current_user
    form = ProfileForm(request.POST, user)
    if request.method == "POST" and form.validate():
        form.populate_obj(user)
        user.save()
        redirect("edit_profile")
    return render_response("edit_profile.html", form=form)

python>>> from wtforms import Form, StringField, validators
>>> class UsernameForm(Form):
...     username = StringField("Username", [validators.Length(min=5)], default=u"test")
...
>>> form = UsernameForm()
>>> form["username"]

>>> form.username.data
u"test"
>>> form.validate()
False
>>> form.errors
{"username": [u"Field must be at least 5 characters long."]}

python>>> form2 = UsernameForm(username=u"Robert")
>>> form2.data
{"username": u"Robert"}
>>> form2.validate()
True

pythondef change_username(request):
    user = request.current_user
    form = ChangeUsernameForm(request.POST, user, username="silly")
    if request.method == "POST" and form.validate():
        user.username = form.username.data
        user.save()
        return redirect("change_username")
    return render_response("change_username.html", form=form)

pythonclass ChangeEmailForm(Form):
    email = StringField("Email", [validators.Length(min=6, max=120), validators.Email()])

pythonclass ChangeEmailForm(Form):
    email = StringField("Email", [
        validators.Length(min=6, message=_(u"Little short for an email address?")),
        validators.Email(message=_(u"That"s not a valid email address."))
    ])

python>>> from wtforms import Form, StringField
>>> class SimpleForm(Form):
...   content = StringField("content")
...
>>> form = SimpleForm(content="foobar")
>>> str(form.content)
""
>>> unicode(form.content)
u""

python>>> form.content(style="width: 200px;", class_="bar")
u""

pythonclass LoginForm(Form):
    username = StringField("Username")
    password = PasswordField("Password")

form = LoginForm()

jinja

    
{{ form.username.label }}: {{ form.username(class="css_class") }}
    
{{ form.password.label }}: {{ form.password() }}

django{% load wtforms %}

    

        {{ form.username.label }}:
        {% form_field form.username class="css_class" %}
    
    

        {{ form.password.label }}:
        {{ form.password }}
    

html

    

        Username:
        
    
    

        Password:
        
    

jinja


    
{{ form.username.label }}: {{ form.username(class="css_class") }}
    {% if form.username.errors %}
        
{% for error in form.username.errors %}
{{ error }}
{% endfor %}
    {% endif %}

    
{{ form.password.label }}: {{ form.password() }}
    {% if form.password.errors %}
        
{% for error in form.password.errors %}
{{ error }}
{% endfor %}
    {% endif %}

jinja{% if form.errors %}
    

        {% for field_name, field_errors in form.errors|dictsort if field_errors %}
            {% for error in field_errors %}
                
{{ form[field_name].label }}: {{ error }}
            {% endfor %}
        {% endfor %}
    
{% endif %}

pythonfrom wtforms.validators import ValidationError

def is_42(form, field):
    if field.data != 42:
        raise ValidationError("Must be 42")

class FourtyTwoForm(Form):
    num = IntegerField("Number", [is_42])

pythonclass FourtyTwoForm(Form):
    num = IntegerField("Number")

    def validate_num(form, field):
        if field.data != 42:
            raise ValidationError(u"Must be 42")