在Python的web框架中中编写日志列表的教程

MVVM模式不但可用于Form表单，在复杂的管理页面中也能大显身手。例如，分页显示Blog的功能，我们先把后端代码写出来：

在apis.py中定义一个Page类用于存储分页信息：

class Page(object):
  def __init__(self, item_count, page_index=1, page_size=10):
    self.item_count = item_count
    self.page_size = page_size
    self.page_count = item_count // page_size + (1 if item_count % page_size > 0 else 0)
    if (item_count == 0) or (page_index < 1) or (page_index > self.page_count):
      self.offset = 0
      self.limit = 0
      self.page_index = 1
    else:
      self.page_index = page_index
      self.offset = self.page_size * (page_index - 1)
      self.limit = self.page_size
    self.has_next = self.page_index < self.page_count
    self.has_previous = self.page_index > 1

在urls.py中实现API：

def _get_blogs_by_page():
  total = Blog.count_all()
  page = Page(total, _get_page_index())
  blogs = Blog.find_by('order by created_at desc limit ?,?', page.offset, page.limit)
  return blogs, page

@api
@get('/api/blogs')
def api_get_blogs():
  blogs, page = _get_blogs_by_page()
  return dict(blogs=blogs, page=page)

返回模板页面：

@view('manage_blog_list.html')
@get('/manage/blogs')
def manage_blogs():
  return dict(page_index=_get_page_index(), user=ctx.request.user)

模板页面首先通过API：GET /api/blogs?page=?拿到Model：

{
  "page": {
    "has_next": true,
    "page_index": 1,
    "page_count": 2,
    "has_previous": false,
    "item_count": 12
  },
  "blogs": [...]
}

然后，通过Vue初始化MVVM：

<script>
function initVM(data) {
  $('#div-blogs').show();
  var vm = new Vue({
    el: '#div-blogs',
    data: {
      blogs: data.blogs,
      page: data.page
    },
    methods: {
      previous: function () {
        gotoPage(this.page.page_index - 1);
      },
      next: function () {
        gotoPage(this.page.page_index + 1);
      },
      edit_blog: function (blog) {
        location.assign('/manage/blogs/edit/' + blog.id);
      }
    }
  });
}

$(function() {
  getApi('/api/blogs?page={{ page_index }}', function (err, results) {
    if (err) {
      return showError(err);
    }
    $('#div-loading').hide();
    initVM(results);
  });
});
</script>

View的容器是#div-blogs，包含一个table，我们用v-repeat可以把Model的数组blogs直接变成多行的<tr>：

<div id="div-blogs" class="uk-width-1-1" style="display:none">
  <table class="uk-table uk-table-hover">
    <thead>
      <tr>
        <th class="uk-width-5-10">标题 / 摘要</th>
        <th class="uk-width-2-10">作者</th>
        <th class="uk-width-2-10">创建时间</th>
        <th class="uk-width-1-10">操作</th>
      </tr>
    </thead>
    <tbody>
      <tr v-repeat="blog: blogs" >
        <td>
          <a target="_blank" v-attr="href: '/blog/'+blog.id" v-text="blog.name"></a>
        </td>
        <td>
          <a target="_blank" v-attr="href: '/user/'+blog.user_id" v-text="blog.user_name"></a>
        </td>
        <td>
          <span v-text="blog.created_at.toDateTime()"></span>
        </td>
        <td>
          <a href="#0" v-on="click: edit_blog(blog)"><i class="uk-icon-edit"></i>
        </td>
      </tr>
    </tbody>
  </table>
  <div class="uk-width-1-1 uk-text-center">
    <ul class="uk-pagination">
      <li v-if="! page.has_previous" class="uk-disabled"><span><i class="uk-icon-angle-double-left"></i></span></li>
      <li v-if="page.has_previous"><a v-on="click: previous()" href="#0"><i class="uk-icon-angle-double-left"></i></a></li>
      <li class="uk-active"><span v-text="page.page_index"></span></li>
      <li v-if="! page.has_next" class="uk-disabled"><span><i class="uk-icon-angle-double-right"></i></span></li>
      <li v-if="page.has_next"><a v-on="click: next()" href="#0"><i class="uk-icon-angle-double-right"></i></a></li>
    </ul>
  </div>
</div>

往Model的blogs数组中增加一个Blog元素，table就神奇地增加了一行；把blogs数组的某个元素删除，table就神奇地减少了一行。所有复杂的Model-View的映射逻辑全部由MVVM框架完成，我们只需要在HTML中写上v-repeat指令，就什么都不用管了。

可以把v-repeat="blog: blogs"看成循环代码，所以，可以在一个<tr>内部引用循环变量blog。v-text和v-attr指令分别用于生成文本和DOM节点属性。

完整的Blog列表页如下：