如何在 simple_form 中使用占位符而不是标签？

Posted 2023-03-05

【中文标题】如何在 simple_form 中使用占位符而不是标签？

【英文标题】：How to use placeholders instead of labels in simple_form?

【发布时间】：2013-08-07 06:38:46

【问题描述】：

我想在我的应用程序中到处使用占位符而不是标签。我正在使用 simple_form 和 Rails (3.2.14)。如何在 simple_form 配置文件中指定使用占位符而不是标签。

在 Initializers 中有一个文件 simple_form.rb 即

# Use this setup block to configure all options available in SimpleForm.
SimpleForm.setup do |config|
  # Wrappers are used by the form builder to generate a
  # complete input. You can remove any component from the
  # wrapper, change the order or even add your own to the
  # stack. The options given below are used to wrap the
  # whole input.
  config.wrappers :default, :class => :input, :hint_class => :field_with_hint, :error_class => :field_with_errors do |b|
    ## Extensions enabled by default
    # Any of these extensions can be disabled for a
    # given input by passing: `f.input EXTENSION_NAME => false`.
    # You can make any of these extensions optional by
    # renaming `b.use` to `b.optional`.

    # Determines whether to use html5 (:email, :url, ...)
    # and required attributes
    b.use :html5

    # Calculates placeholders automatically from I18n
    # You can also pass a string as f.input :placeholder => "Placeholder"
    b.use :placeholder

    ## Optional extensions
    # They are disabled unless you pass `f.input EXTENSION_NAME => :lookup`
    # to the input. If so, they will retrieve the values from the model
    # if any exists. If you want to enable the lookup for any of those
    # extensions by default, you can change `b.optional` to `b.use`.

    # Calculates maxlength from length validations for string inputs
    b.optional :maxlength

    # Calculates pattern from format validations for string inputs
    b.optional :pattern

    # Calculates min and max from length validations for numeric inputs
    b.optional :min_max

    # Calculates readonly automatically from readonly attributes
    b.optional :readonly

    ## Inputs
    b.use :label_input
    b.use :hint,  :wrap_with =>  :tag => :span, :class => :hint 
    b.use :error, :wrap_with =>  :tag => :span, :class => :error 
  end

  # The default wrapper to be used by the FormBuilder.
  config.default_wrapper = :default

  # Define the way to render check boxes / radio buttons with labels.
  # Defaults to :nested for bootstrap config.
  #   :inline => input + label
  #   :nested => label > input
  config.boolean_style = :nested

  # Default class for buttons
  config.button_class = 'btn'

  # Method used to tidy up errors. Specify any Rails Array method.
  # :first lists the first message for each field.
  # Use :to_sentence to list all errors for each field.
  # config.error_method = :first

  # Default tag used for error notification helper.
  config.error_notification_tag = :div

  # CSS class to add for error notification helper.
  config.error_notification_class = 'alert alert-error'

  # ID to add for error notification helper.
  # config.error_notification_id = nil

  # Series of attempts to detect a default label method for collection.
  # config.collection_label_methods = [ :to_label, :name, :title, :to_s ]

  # Series of attempts to detect a default value method for collection.
  # config.collection_value_methods = [ :id, :to_s ]

  # You can wrap a collection of radio/check boxes in a pre-defined tag, defaulting to none.
  # config.collection_wrapper_tag = nil

  # You can define the class to use on all collection wrappers. Defaulting to none.
  # config.collection_wrapper_class = nil

  # You can wrap each item in a collection of radio/check boxes with a tag,
  # defaulting to :span. Please note that when using :boolean_style = :nested,
  # SimpleForm will force this option to be a label.
  # config.item_wrapper_tag = :span

  # You can define a class to use in all item wrappers. Defaulting to none.
  # config.item_wrapper_class = nil

  # How the label text should be generated altogether with the required text.
  # config.label_text = lambda  |label, required| "#required #label" 

  # You can define the class to use on all labels. Default is nil.
  config.label_class = 'control-label'

  # You can define the class to use on all forms. Default is simple_form.
  # config.form_class = :simple_form

  # You can define which elements should obtain additional classes
  # config.generate_additional_classes_for = [:wrapper, :label, :input]

  # Whether attributes are required by default (or not). Default is true.
  # config.required_by_default = true

  # Tell browsers whether to use default HTML5 validations (novalidate option).
  # Default is enabled.
  config.browser_validations = false

  # Collection of methods to detect if a file type was given.
  # config.file_methods = [ :mounted_as, :file?, :public_filename ]

  # Custom mappings for input types. This should be a hash containing a regexp
  # to match as key, and the input type that will be used when the field name
  # matches the regexp as value.
  # config.input_mappings =  /count/ => :integer 

  # Custom wrappers for input types. This should be a hash containing an input
  # type as key and the wrapper that will be used for all inputs with specified type.
  # config.wrapper_mappings =  :string => :prepend 

  # Default priority for time_zone inputs.
  # config.time_zone_priority = nil

  # Default priority for country inputs.
  # config.country_priority = nil

  # Default size for text inputs.
  # config.default_input_size = 50

  # When false, do not use translations for labels.
  # config.translate_labels = true

  # Automatically discover new inputs in Rails' autoload path.
  # config.inputs_discovery = true

  # Cache SimpleForm inputs discovery
  # config.cache_discovery = !Rails.env.development?
end

【问题讨论】：

Simple Form: Is it possible to remove labels and replace them with placeholders using the labels i18n? 的可能重复项

依赖占位符作为标签的行为存在 UI 和可访问性缺陷。一旦字段有内容，标签就会消失，占位符对比度非常低，很难看到，而且屏幕阅读器软件可能根本不会宣布占位符。也许值得考虑替代品。 Sky-labels 试图通过在字段内浮动标签来找到中间立场。至少考虑增加占位符与 CSS 中 ::-<webkit|moz|ms>-input-placeholder 选择器的对比度。

【参考方案1】：

Using placeholders instead of labels is bad practice，因为它降低了辅助技术用户对表单的可访问性。

这并不意味着您无法实现您正在寻找的视觉效果：您可以使用 simple_form 的默认行为来创建标签，然后使用 CSS 设置它们的样式，使其看起来像占位符。 SkyLabels.js 之类的库有助于在不降低可访问性的情况下创建这种视觉效果。

作为一般规则，选择 HTML 元素和属性是因为它们的语义而不是它们的默认外观。

【参考方案2】：

您需要 3 个步骤来启用自动显示占位符而不是标签，并且需要进行更多配置。

确保在 simple_form.rb 中 b.use :placeholder

确保b.use :input 而不是b.use :label_input

最重要的是，修改你的 simple_form.en.yml：

en:   
  simple_form:
    "yes": 'Yes'
    "no": 'No'
    required:
      text: 'required'
      mark: '*'
    placeholders:
      user:
        name: 'name'

在您的页面中：

<%= simple_form_for @user do |f|%>
  <%= f.input :name%>
<% end%>

每个占位符都需要在这里定义，否则不会显示。

【讨论】：

别忘了重启你的服务器：touch tmp/restart.txt（或powder）

【参考方案3】：

支持引导表单的解决方案

为了让它与 Bootstrap 一起使用，我必须更新 simple_form_bootstrap.rb 并注释掉配置中 vertical_form 和 horizontal_form 的 b.use :label 条目：

#b.use :label, class: 'control-label'
b.use :placeholder

然后正如@Bigxiang 正确提到的那样，占位符都需要在您的simple_form.LANG.yml 中定义一个值。

en:
  placeholders:
    defaults:
      first_name: First name
      last_name: Last name
    user:
      email: Email

请注意，当您使用通用defaults 翻译时，您不必指定模型，例如我的示例中的first_name、last_name。

【参考方案4】：

simple_form 允许您通过传入隐藏单个标签 label:false 到每个输入。例如： <%= f.input :email, placeholder: 'Email', label:false %> 将在表单中隐藏您的电子邮件输入的标签。

【参考方案5】：

您只需在 initializers/simple_form.rb 处进行更改：

## Inputs
b.use :label_input

到

## Inputs
b.use :input

并且，在您看来，只需使用属性 :placeholder 而不是 :label

【讨论】：

在视图中我只使用这个： true %>