我有这段代码可以为我生成一个下拉菜单，默认值为Unassigned。
但是，我想做的是在下拉菜单上有一个占位符选择位置，尽管默认情况下所选的值为“未分配”
代码：
= f.select :training_location_id, grouped_options_for_select(grouped_location_options, current_provider.locations.where(name: 'Unassigned').map { |loc| loc.id }), { placeholder: 'Select Location', include_blank: true }, class: 'form-control'
您可以在代码中看到，我在 f.select {options}中设置了一个占位符，但是下拉菜单中仍然显示“未分配”
智慧的话？
答案 0 :(得分：0)
尝试include_blank: 'Select Location'
= f.select :training_location_id, grouped_options_for_select(grouped_location_options, current_provider.locations.where(name: 'Unassigned').map { |loc| loc.id }), include_blank: 'Select Location' , class: 'form-control'
答案 1 :(得分：0)
尝试一下，这可能对您有用：
= f.select :training_location_id, grouped_options_for_select(grouped_location_options, current_provider.locations.where(name: 'Unassigned').map { |loc| loc.id }), data: { placeholder: 'Select Location' }, class: 'form-control'
答案 2 :(得分：0)
1-使用find_by或where
而不是使用地图来获取选择的选项 <%=f.select :training_location_id, grouped_options_for_select(grouped_location_options, current_provider.locations.where(name: 'Unassigned').first.id, {:prompt => '-- Select Location --'}),{class: 'form-control'}%>
或
<%=f.select :training_location_id, grouped_options_for_select(grouped_location_options, current_provider.locations.find_by(name: 'Unassigned').id, {:prompt => '-- Select Location --'}),{class: 'form-control'}%>
参考：=