如何解决未初始化的常量Search :: error

我正在为与汽车维护相关的约会模型创建一个高级搜索/过滤器，其中schema.rb中的每个表都是：

create_table "appointments", force: :cascade do |t|

t.string "VIN"
t.string "owner_email"
t.string "date"
t.string "time"
t.string "reason"
t.string "parts_needed"
t.string "hours_needed"
t.string "cost"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false

end

create_table "searches", force: :cascade do |t|

t.string "VIN"
t.string "email"
t.string "after_date"
t.string "before_date"
t.string "time"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false

end
在我的search.rb模型中，我定义了搜索功能：

class Search < ApplicationRecord

def search_appointments
    appointments = Appointment.all
    # appointments = appointments.where("VIN LIKE ?", VIN) if VIN.present? GIVES ERROR
    appointments = appointments.where("owner_email LIKE ?", email) if email.present?
    appointments = appointments.where("date >= ?", after_date) if after_date.present?
    appointments = appointments.where("date <= ?", before_date) if before_date.present?
    if !time=="Any"
        appointments = appointments.where("time LIKE ?", time) if time.present?
    end

    return appointments
end

end
然后在我的show.html.erb中显示生成的过滤器：

Search Results

<% if @search.search_appointments.empty? %>
    <p> No Appointments Fit This Search</p>

<% else %>
    <%= @search.search_appointments.each do |a| %>

    Email: <%= a.owner_email%> </br>
    Date: <%= a.date%> </br>
    Time: <%= a.time%> </br>
    VIN: <%= a.VIN %> </br>

    </br>
    </br>
    </br>
    <% end %>
<% end %>
</br>
<%= link_to 'Return', @search, method: :delete %>

uninitialized constant Search::VIN
我不明白为什么会这样，因为所有其他过滤器工作得很好。
搜索控制器：

class SearchesController < ApplicationController

def new
    @search = Search.new
end

def create
    @search = Search.create(search_params)
    redirect_to @search
end

def show
    @search = Search.find(params[:id])
end

def destroy
    @search = Search.find(params[:id])
    @search.destroy

    redirect_to admin_path
end

def search_params
    params.require(:search).permit(:VIN, :email, :after_date, :before_date, :time)
end

end
我的“新”页面是用户填写过滤器参数，然后单击“提交”按钮将其带到列出已过滤约会的显示页面的表单。