如何向 WTForms 添加 Bootstrap 验证

Question

我将 WTForms 与 Flask 结合使用，我想集成Bootstrap 表单验证来检查表单中的错误。我有一个基本的登录表单设置，如下所示：

class LoginForm(FlaskForm):
    """Login form."""

    email = EmailField(
        "Email Address", validators=[DataRequired(), Email(), Length(min=6, max=40)]
    )
    password = PasswordField(
        "Password", validators=[DataRequired()]
    )

    def __init__(self, *args, **kwargs):
        """Create instance."""
        super(LoginForm, self).__init__(*args, **kwargs)
        self.user = None

    def validate(self):
        """Validate the form."""
        initial_validation = super(LoginForm, self).validate()
        if not initial_validation:
            return False

        self.user = User.query.filter_by(email=self.email.data).first()
        if not self.user:
            self.email.errors.append("Unknown email address!")
            return False

        if not self.user.check_password(self.password.data):
            self.password.errors.append("Invalid password!")
            return False

        if not self.user.verified:
            self.email.errors.append("Please verify your email address!")
            return False
        return True

我的 login.html 模板设置如下：

<form method="POST" action="{{ url_for('public.login') }}" role="form">
                  {{ form.csrf_token }}
                  <div class="form-group">
                    {{ form.email.label(class_="form-control-label") }}
                    <div class="input-group input-group-merge">
                      <div class="input-group-prepend">
                        <span class="input-group-text"><i class="fas fa-user"></i></span>
                      </div>
                      {{ form.email(placeholder="name@example.com", class_="form-control") }}
                    </div>
                  </div>
                  <div class="form-group mb-4">
                    <div class="d-flex align-items-center justify-content-between">
                      <div>
                        {{ form.password.label(class_="form-control-label") }}
                      </div>
                      <div class="mb-2">
                        <a href="{{ url_for('public.recover') }}" class="small text-muted text-underline--dashed border-primary">Lost password?</a>
                      </div>
                    </div>
                    <div class="input-group input-group-merge">
                      <div class="input-group-prepend">
                        <span class="input-group-text"><i class="fas fa-key"></i></span>
                      </div>
                      {{ form.password(placeholder="Password", class_="form-control") }}
                      <div class="input-group-append" onclick="togglePassword()">
                        <span class="input-group-text">
                          <i class="fas fa-eye"></i>
                        </span>
                      </div>
                    </div>
                  </div>
                  <div class="row mt-4">
                    <div class="col-md-auto mt-1 mb-2" align="center">
                      <button type="submit" class="btn btn-sm btn-primary btn-icon rounded-pill">
                        <span class="btn-inner--text">Sign in</span>
                        <span class="btn-inner--icon"><i class="fas fa-long-arrow-alt-right"></i></span>
                      </button>
                    </div>
                    <div class="col-md-auto text-center mt-2">
                      <p class="text-secondary-dark">or</p>
                      </div>
                    <div class="col-md-auto" align="center">
                      <button type="button" class="btn btn-md btn-secondary btn-icon-only">
                          <span class="btn-inner--icon">
                              <i class="fab fa-google"></i>
                          </span>
                      </button>

                      <button type="button" class="btn btn-md btn-secondary btn-icon-only">
                          <span class="btn-inner--icon">
                              <i class="fab fa-linkedin"></i>
                          </span>
                      </button>
                    </div>
                  </div>
                </form>

我想显示使用 WTForms 验证的错误，但我不确定如何将原始表单元素的类更改为is-invalidor is-valid，以及如何为每个错误创建标签。我研究过宏，但它们似乎也无法修改表单元素。

有人能指出我正确的方向吗？

Answer 1

我遇到了同样的问题，我想避免使用任何第三个包（flask-bootstrap），所以我想出了这个简单的解决方案：

<div class="form-group">
  {{ form.email.label }} <span class="text-danger">*</span>

  {# her #}
  {{ form.email(class="form-control" + (" is-invalid" if form.email.errors else "") + " rounded-0 shadow-none", **{"placeholder": "Your Email", "aria-describedby": "emailHelp", "autocomplete": "off"}) }}


  <small id="emailHelp" class="form-text text-muted">We'll never share your data with anyone else.</small>

  {% if form.email.errors %}
    {% for error in form.email.errors %}
      <div class="invalid-feedback">{{ error }}</div>
    {% endfor %}
  {% endif %}
</div>

诀窍是使用简单的三元表达式与字符串连接相结合。

Answer 2

@cizario 的回答是一个很好的开始。但是，我找到了更好的错误实现。使用WTForm 的自定义小部件，您可以获得以下小部件：

from wtforms.widgets import PasswordInput, CheckboxInput, TextInput
from wtforms.widgets.html5 import EmailInput


class BootstrapVerifyEmail(EmailInput):
    """Bootstrap Validator for email"""

    def __init__(self, error_class=u"is-invalid"):
        super(BootstrapVerifyEmail, self).__init__()
        self.error_class = error_class

    def __call__(self, field, **kwargs):
        if field.errors:
            c = kwargs.pop("class", "") or kwargs.pop("class_", "")
            kwargs["class"] = u"%s %s" % (self.error_class, c)
        return super(BootstrapVerifyEmail, self).__call__(field, **kwargs)


class BootstrapVerifyPassword(PasswordInput):
    """Bootstrap Validator for password"""

    def __init__(self, error_class=u"is-invalid"):
        super(BootstrapVerifyPassword, self).__init__()
        self.error_class = error_class

    def __call__(self, field, **kwargs):
        if field.errors:
            c = kwargs.pop("class", "") or kwargs.pop("class_", "")
            kwargs["class"] = u"%s %s" % (self.error_class, c)
        return super(BootstrapVerifyPassword, self).__call__(field, **kwargs)


class BootstrapVerifyBoolean(CheckboxInput):
    """Bootstrap Validator for boolean"""

    def __init__(self, error_class=u"is-invalid"):
        super(BootstrapVerifyBoolean, self).__init__()
        self.error_class = error_class

    def __call__(self, field, **kwargs):
        if field.errors:
            c = kwargs.pop("class", "") or kwargs.pop("class_", "")
            kwargs["class"] = u"%s %s" % (self.error_class, c)
        return super(BootstrapVerifyBoolean, self).__call__(field, **kwargs)


class BootstrapVerifyText(TextInput):
    """Bootstrap Validator for text"""

    def __init__(self, error_class=u"is-invalid"):
        super(BootstrapVerifyText, self).__init__()
        self.error_class = error_class

    def __call__(self, field, **kwargs):
        if field.errors:
            c = kwargs.pop("class", "") or kwargs.pop("class_", "")
            kwargs["class"] = u"%s %s" % (self.error_class, c)
        return super(BootstrapVerifyText, self).__call__(field, **kwargs)

这将添加无效标签，以便引导程序可以将其标记为无效。在 HTML 中，执行如下操作来添加错误消息：

{{ login_user_form.email.label(class_="form-control-label") }}
<div class="input-group input-group-merge">
    <div class="input-group-prepend">
        <span class="input-group-text" id="user"><i class="fas fa-user"></i></span>
    </div>
    {{ login_user_form.email(placeholder="name@example.com", class_="form-control", **{"aria-describedby": "inputGroupPrepend3", "required": ""}) }}
    {% for error in login_user_form.email.errors %}
        <div class="invalid-feedback">{{ error }}</div>
    {% endfor %}
</div>