摘要：你打了個響指然后開始致力于你想寫的棒極了的網絡應用程序你寫完一些頁面最后你需要著手處理令人討厭的任務處理和驗證表單輸入進入開始但是為什么我需要另一個框架呢好吧一些網絡應用程序框架采用數據庫模型和表單處理相結合的方法同時這對很基本的創建更新視

你打了個響指, 然后開始致力于你想寫的棒極了的 Python 網絡應用程序. 你寫完一些頁面, 最后你需要著手處理令人討厭的任務：處理和驗證表單輸入. 進入（開始）WTForms.

但是, 為什么我需要另一個框架呢？好吧, 一些網絡應用程序框架采用數據庫模型和表單處理相結合的方法. 同時這對很基本的創建/更新視圖函數是很方便的, 可能性是不是每個你需要的表單都能直接映射到一個數據庫模型. 也許你已經使用通用的表單處理框架, 只是你想要定制這些表單域的 HTML 代碼生成, 并且定義屬于你的驗證器.

使用 WTForms, 你能生成屬于你的表單域的 HTML 代碼, 此外我們允許你在模板中定制它. 這允許你維持獨立的代碼和展現, 并把這些凌亂的參數保留在 Python 代碼之外. 因為我們爭取松耦合, 同樣的, 你應該可以在你喜歡的任意的模板引擎中這么做.

  
備注: 本人未過四級, 翻譯水平有限, 歡迎指正.

安裝 WTForms 最簡單的方式是使用 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")