Bootstrap模态表单字段自动对焦第二次不起作用

Question

我在我的rails应用程序中使用bootstrap模式（Bootstrap版本3.2.0）

因为我已经为表单字段添加了自动对焦。首先打开模态它会自动聚焦字段。但是第二次它不起作用。

这里我添加了一些代码

<button type="button" id="myModalCreateButton" class="btn btn-primary" data-toggle="modal" data-target="#myModal" >
                        Create New Project
</button>

模态中的表格

<div class="modal fade" id="myModal"  role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
<div class="modal-dialog">
    <div class="modal-content">
        <div class="modal-header">
            <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                <span aria-hidden="true">&times;</span>
            </button>
            <h4 class="modal-title second-color" id="myModalLabel">Create New Project</h4>
        </div>
        <%= form_for(@newproject) do |f| %>
        <div class="modal-body">
            <div class="form-group single-field">
                <label for="exampleInputEmail1">Project Name</label>
                <input type="text" class="form-control" id="newProjectField" placeholder="Enter project name" name="project[project_name]" autofocus >
            </div>
        </div>
        <div class="modal-footer">
            <button type="button" class="btn btn-default" data-dismiss="modal">
                Cancel
            </button>
            <button type="button" class="btn btn-primary" id="createProjectButton" autofocus >
                Create
            </button>
        </div>
        <% end %>
    </div>
</div>