word.charAt不是函数，Datatable错误

Question

我在我的Rails应用程序（4.2.4）中集成了数据表，如下所示：

的application.js

//= require datatables.js
//= require ../metronic/assets/global/plugins/datatables/media/js/jquery.dataTables.js
//= require ../metronic/assets/global/plugins/datatables/media/js/dataTables.bootstrap.js

使用的一个例子是索引页面：

<table id="students" class="datatable  table table-striped table-hover table-datatable">
                <thead>
                    <tr>
                        <th class="left">Nome</th>
                        <th class="left">Cognome</th>
                        <th class="left">Classe</th>
                        <th class="left">Codice Fiscale</th>
                        <th class="left">Indirizzo</th>
                        <th class="left">Email</th>
                        <th class="left">Cellulare</th>

                        <th/>
                    </tr>
                </thead>

                <tbody>
                    <% @students.each do |student| %>
                    <tr>
                        <td class="left"><%= student.nome %></td>
                        <td class="left"><%= student.cognome %></td>
                        <td class="left"><%= student.sigla_classe%></td>
                        <td class="left"><%= student.codice_fiscale %></td>
                        <td class="left"><%= student.indirizzo %></td>
                        <td class="left"><%= student.email %></td>
                        <td class="left"><%= student.cell %></td>
                        <td class="right">
                            <%= link_to 'Vedi', student %>
                            |
                            <%= link_to 'Modifica', edit_student_path(id: student) %>
                            |
                            <%= link_to 'Elimina', student, style:'color:#F00;', method: :delete, data: { confirm: 'Sei sicuro?' } %>
                        </td>
                    </tr>
                    <% end %>
                </tbody>
            </table>

这是控制器：

def index
        @students = Student.all
        respond_to do |format|
            format.html
            format.pdf do
                pdf = StudentPdf.new(@students, view_context)
                send_data pdf.render,
                          filename: 'Elenco Studenti',
                          type: 'application/pdf',
                          disposition: 'inline'
            end
        end
      end

如果我进行搜索，错误就会消失，我只是无法弄清楚我做错了什么，我不认为索引中的错误几乎可以肯定错误在于我整合数据表的方式。

其余一切正常，表格显示正确的分页。