发布于 2017-10-29 16:46:53 | 93 次阅读 | 评论: 0 | 来源: 网友投递

这里有新鲜出炉的Flask Mega-Tutorial中文版,程序狗速度看过来!

Flask 轻量级Python Web开发框架

Flask是一个使用Python编写的轻量级Web应用框架。基于Werkzeug WSGI工具箱和Jinja2 模板引擎。使用 BSD 授权。


Flask-Admin是一个为Python的Flask框架服务的微型框架,可以像Django-Admin那样为用户生成Model层面的数据管理界面,接下来就一起来看一下Flask的图形化管理界面搭建框架Flask-Admin的使用教程

Flask-Admin是Flask框架的一个扩展,用它能够快速创建Web管理界面,它实现了比如用户、文件的增删改查等常用的管理功能;如果对它的默认界面不喜欢,可以通过修改模板文件来定制;
Flask-Admin把每一个菜单(超链接)看作一个view,注册后才能显示出来,view本身也有属性来控制其是否可见;因此,利用这个机制可以定制自己的模块化界面,比如让不同权限的用户登录后看到不一样的菜单;

项目地址:https://flask-admin.readthedocs.io/en/latest/

example/simple
这是最简单的一个样例,可以帮助我们快速、直观的了解基本概念,学会定制Flask-Admin的界面
simple.py:


from flask import Flask

from flask.ext import admin


# Create custom admin view
class MyAdminView(admin.BaseView):
  @admin.expose('/')
  def index(self):
    return self.render('myadmin.html')


class AnotherAdminView(admin.BaseView):
  @admin.expose('/')
  def index(self):
    return self.render('anotheradmin.html')

  @admin.expose('/test/')
  def test(self):
    return self.render('test.html')


# Create flask app
app = Flask(__name__, template_folder='templates')
app.debug = True

# Flask views
@app.route('/')
def index():
  return '<a href="/admin/">Click me to get to Admin!</a>'

# Create admin interface
admin = admin.Admin()
admin.add_view(MyAdminView(category='Test'))
admin.add_view(AnotherAdminView(category='Test'))
admin.init_app(app)

if __name__ == '__main__':

  # Start app
  app.run()

在这里可以看到运行效果

BaseView

所有的view都必须继承自BaseView:



class BaseView(name=None, category=None, endpoint=None, url=None, static_folder=None, static_url_path=None)


name: view在页面上表现为一个menu(超链接),menu name == 'name',缺省就用小写的class name
category: 如果多个view有相同的category就全部放到一个dropdown里面(dropdown name=='category')
endpoint: 假设endpoint='xxx',则可以用url_for(xxx.index),也能改变页面URL(/admin/xxx)
url: 页面URL,优先级url > endpoint > class name
static_folder: static目录的路径
static_url_path: static目录的URL
anotheradmin.html:


{% extends 'admin/master.html' %}
{% block body %}
  Hello World from AnotherMyAdmin!<br/>
  <a href="{{ url_for('.test') }}">Click me to go to test view</a>
{% endblock %}

如果AnotherAdminView增加参数endpoint='xxx',那这里就可以写成url_for('xxx.text'),然后页面URL会由/admin/anotheradminview/变成/admin/xxx
如果同时指定参数url='aaa',那页面URL会变成/admin/aaa,url优先级比endpoint高
Admin



class Admin(app=None, name=None, url=None, subdomain=None, index_view=None, translations_path=None, endpoint=None, static_url_path=None, base_template=None)


app: Flask Application Object;本例中可以不写admin.init_app(app),直接用admin = admin.Admin(app=app)是一样的
name: Application name,缺省'Admin';会显示为main menu name('Home'左边的'Admin')和page title
subdomain: ???
index_view: 'Home'那个menu对应的就叫index view,缺省AdminIndexView
base_template: 基础模板,缺省admin/base.html,该模板在Flask-Admin的源码目录里面
部分Admin代码如下:

class MenuItem(object):
  """
    Simple menu tree hierarchy.
  """
  def __init__(self, name, view=None):
    self.name = name
    self._view = view
    self._children = []
    self._children_urls = set()
    self._cached_url = None
    self.url = None
    if view is not None:
      self.url = view.url

  def add_child(self, view):
    self._children.append(view)
    self._children_urls.add(view.url)

class Admin(object):

  def __init__(self, app=None, name=None,
         url=None, subdomain=None,
         index_view=None,
         translations_path=None,
         endpoint=None,
         static_url_path=None,
         base_template=None):

    self.app = app

    self.translations_path = translations_path

    self._views = []
    self._menu = []
    self._menu_categories = dict()
    self._menu_links = []

    if name is None:
      name = 'Admin'
    self.name = name

    self.index_view = index_view or AdminIndexView(endpoint=endpoint, url=url)
    self.endpoint = endpoint or self.index_view.endpoint
    self.url = url or self.index_view.url
    self.static_url_path = static_url_path
    self.subdomain = subdomain
    self.base_template = base_template or 'admin/base.html'

    # Add predefined index view
    self.add_view(self.index_view)

    # Register with application
    if app is not None:
      self._init_extension()

  def add_view(self, view):

    # Add to views
    self._views.append(view)

    # If app was provided in constructor, register view with Flask app
    if self.app is not None:
      self.app.register_blueprint(view.create_blueprint(self))
      self._add_view_to_menu(view)

  def _add_view_to_menu(self, view):

    if view.category:
      category = self._menu_categories.get(view.category)

      if category is None:
        category = MenuItem(view.category)
        self._menu_categories[view.category] = category
        self._menu.append(category)

      category.add_child(MenuItem(view.name, view))
    else:
      self._menu.append(MenuItem(view.name, view))

  def init_app(self, app):

    self.app = app

    self._init_extension()

    # Register views
    for view in self._views:
      app.register_blueprint(view.create_blueprint(self))
      self._add_view_to_menu(view)

从上面的代码可以看出init_app(app)和Admin(app=app)是一样的:
将每个view注册为blueprint(Flask里的概念,可以简单理解为模块)
记录所有view,以及所属的category和url
AdminIndexView



class AdminIndexView(name=None, category=None, endpoint=None, url=None, template='admin/index.html')


name: 缺省'Home'
endpoint: 缺省'admin'
url: 缺省'/admin'
如果要封装出自己的view,可以参照AdminIndexView的写法:


class AdminIndexView(BaseView):

  def __init__(self, name=None, category=None,
         endpoint=None, url=None,
         template='admin/index.html'):
    super(AdminIndexView, self).__init__(name or babel.lazy_gettext('Home'),
                       category,
                       endpoint or 'admin',
                       url or '/admin',
                       'static')
    self._template = template

  @expose()
  def index(self):
    return self.render(self._template)
base_template

base_template缺省是/admin/base.html,是页面的主要代码(基于bootstrap),它里面又import admin/layout.html;
layout是一些宏,主要用于展开、显示menu;
在模板中使用一些变量来取出之前注册view时保存的信息(如menu name和url等):
# admin/layout.html (部分)


{% macro menu() %}
 {% for item in admin_view.admin.menu() %}
  {% if item.is_category() %}
   {% set children = item.get_children() %}
   {% if children %}
    {% if item.is_active(admin_view) %}<li class="active dropdown">{% else %}<li class="dropdown">{% endif %}
     <a class="dropdown-toggle" data-toggle="dropdown" href="javascript:void(0)">{{ item.name }}<b class="caret"></b></a>
     <ul class="dropdown-menu">
      {% for child in children %}
       {% if child.is_active(admin_view) %}<li class="active">{% else %}<li>{% endif %}
        <a href="{{ child.get_url() }}">{{ child.name }}</a>
       </li>
      {% endfor %}
     </ul>
    </li>
   {% endif %}
  {% else %}
   {% if item.is_accessible() and item.is_visible() %}
    {% if item.is_active(admin_view) %}<li class="active">{% else %}<li>{% endif %}
     <a href="{{ item.get_url() }}">{{ item.name }}</a>
    </li>
   {% endif %}
  {% endif %}
 {% endfor %}
{% endmacro %}

example/file
这个样例能帮助我们快速搭建起文件管理界面,但我们的重点是学习使用ActionsMixin模块
file.py:


import os
import os.path as op

from flask import Flask

from flask.ext import admin
from flask.ext.admin.contrib import fileadmin

# Create flask app
app = Flask(__name__, template_folder='templates', static_folder='files')

# Create dummy secrey key so we can use flash
app.config['SECRET_KEY'] = '123456790'


# Flask views
@app.route('/')
def index():
  return '<a href="/admin/">Click me to get to Admin!</a>'


if __name__ == '__main__':
  # Create directory
  path = op.join(op.dirname(__file__), 'files')
  try:
    os.mkdir(path)
  except OSError:
    pass

  # Create admin interface
  admin = admin.Admin(app)
  admin.add_view(fileadmin.FileAdmin(path, '/files/', name='Files'))

  # Start app
  app.run(debug=True)

FileAdmin是已经写好的的一个view,直接用即可:



class FileAdmin(base_path, base_url, name=None, category=None, endpoint=None, url=None, verify_path=True)


base_path: 文件存放的相对路径
base_url: 文件目录的URL
FileAdmin中和ActionsMixin相关代码如下:
class FileAdmin(BaseView, ActionsMixin):


  def __init__(self, base_path, base_url,
         name=None, category=None, endpoint=None, url=None,
         verify_path=True):

    self.init_actions()

@expose('/action/', methods=('POST',))
def action_view(self):
  return self.handle_action()

# Actions
@action('delete',
    lazy_gettext('Delete'),
    lazy_gettext('Are you sure you want to delete these files?'))
def action_delete(self, items):
  if not self.can_delete:
    flash(gettext('File deletion is disabled.'), 'error')
    return

  for path in items:
    base_path, full_path, path = self._normalize_path(path)

    if self.is_accessible_path(path):
      try:
        os.remove(full_path)
        flash(gettext('File "%(name)s" was successfully deleted.', name=path))
      except Exception as ex:
        flash(gettext('Failed to delete file: %(name)s', name=ex), 'error')

@action('edit', lazy_gettext('Edit'))
def action_edit(self, items):
  return redirect(url_for('.edit', path=items))
@action()用于wrap跟在后面的函数,这里的作用就是把参数保存起来:
def action(name, text, confirmation=None)
  def wrap(f):
    f._action = (name, text, confirmation)
    return f

  return wrap

name: action name
text: 可用于按钮名称
confirmation: 弹框确认信息
init_actions()把所有action的信息保存到ActionsMixin里面:


# 调试信息
_actions = [('delete', lu'Delete'), ('edit', lu'Edit')]
_actions_data = {'edit': (<bound method FileAdmin.action_edit of <flask_admin.contrib.fileadmin.FileAdmin object at 0x1aafc50>>, lu'Edit', None), 'delete': (<bound method FileAdmin.action_delete of <flask_admin.contrib.fileadmin.FileAdmin object at 0x1aafc50>>, lu'Delete', lu'Are you sure you want to delete these files?')}

action_view()用于处理POST给/action/的请求,然后调用handle_action(),它再调用不同的action处理,最后返回当前页面:


# 省略无关代码
def handle_action(self, return_view=None):

  action = request.form.get('action')
  ids = request.form.getlist('rowid')

  handler = self._actions_data.get(action)

  if handler and self.is_action_allowed(action):
    response = handler[0](ids)

    if response is not None:
      return response

  if not return_view:
    url = url_for('.' + self._default_view)
  else:
    url = url_for('.' + return_view)

  return redirect(url)

ids是一个文件清单,作为参数传给action处理函数(参数items):


# 调试信息
ids: [u'1.png', u'2.png']

再分析页面代码,Files页面对应文件为admin/file/list.html,重点看With selected下拉菜单相关代码:
{% import 'admin/actions.html' as actionslib with context %}


{% if actions %}
  <div class="btn-group">
    {{ actionslib.dropdown(actions, 'dropdown-toggle btn btn-large') }}
  </div>
{% endif %}

{% block actions %}
  {{ actionslib.form(actions, url_for('.action_view')) }}
{% endblock %}

{% block tail %}
  {{ actionslib.script(_gettext('Please select at least one file.'),
           actions,
           actions_confirmation) }}
{% endblock %}

上面用到的三个宏在actions.html:


{% macro dropdown(actions, btn_class='dropdown-toggle') -%}
  <a class="{{ btn_class }}" data-toggle="dropdown" href="javascript:void(0)">{{ _gettext('With selected') }}<b class="caret"></b></a>
  <ul class="dropdown-menu">
    {% for p in actions %}
    <li>
      <a href="javascript:void(0)" onclick="return modelActions.execute('{{ p[0] }}');">{{ _gettext(p[1]) }}</a>
    </li>
    {% endfor %}
  </ul>
{% endmacro %}

{% macro form(actions, url) %}
  {% if actions %}
  <form id="action_form" action="{{ url }}" method="POST" style="display: none">
    {% if csrf_token %}
    <input type="hidden" name="csrf_token" value="{{ csrf_token() }}"/>
    {% endif %}
    <input type="hidden" id="action" name="action" />
  </form>
  {% endif %}
{% endmacro %}

{% macro script(message, actions, actions_confirmation) %}
  {% if actions %}
  <script src="{{ admin_static.url(filename='admin/js/actions.js') }}"></script>
  <script language="javascript">
    var modelActions = new AdminModelActions({{ message|tojson|safe }}, {{ actions_confirmation|tojson|safe }});
  </script>
  {% endif %}
{% endmacro %}

最终生成的页面(部分):


<div class="btn-group">
  <a class="dropdown-toggle btn btn-large" href="javascript:void(0)" data-toggle="dropdown">
    With selected
    <b class="caret"></b>
  </a>

  <ul class="dropdown-menu">
    <li>
      <a onclick="return modelActions.execute('delete');" href="javascript:void(0)">Delete</a>
    </li>
    <li>
      <a onclick="return modelActions.execute('edit');" href="javascript:void(0)">Edit</a>
    </li>
  </ul>
</div>

<form id="action_form" action="/admin/fileadmin/action/" method="POST" style="display: none">
  <input type="hidden" id="action" name="action" />
</form>

<script src="/admin/static/admin/js/actions.js"></script>
<script language="javascript">
  var modelActions = new AdminModelActions("Please select at least one file.", {"delete": "Are you sure you want to delete these files?"});
</script>

选择菜单后的处理方法在actions.js:


var AdminModelActions = function(actionErrorMessage, actionConfirmations) {
  // Actions helpers. TODO: Move to separate file
  this.execute = function(name) {
    var selected = $('input.action-checkbox:checked').size();

    if (selected === 0) {
      alert(actionErrorMessage);
      return false;
    }

    var msg = actionConfirmations[name];

    if (!!msg)
      if (!confirm(msg))
        return false;

    // Update hidden form and submit it
    var form = $('#action_form');
    $('#action', form).val(name);

    $('input.action-checkbox', form).remove();
    $('input.action-checkbox:checked').each(function() {
      form.append($(this).clone());
    });

    form.submit();

    return false;
  };

  $(function() {
    $('.action-rowtoggle').change(function() {
      $('input.action-checkbox').attr('checked', this.checked);
    });
  });
};

对比一下修改前后的表单:


# 初始化
<form id="action_form" style="display: none" method="POST" action="/admin/fileadmin/action/">
  <input id="action" type="hidden" name="action">
</form>

# 'Delete'选中的三个文件
<form id="action_form" style="display: none" method="POST" action="/admin/fileadmin/action/">
  <input id="action" type="hidden" name="action" value="delete">
  <input class="action-checkbox" type="checkbox" value="1.png" name="rowid">
  <input class="action-checkbox" type="checkbox" value="2.png" name="rowid">
  <input class="action-checkbox" type="checkbox" value="3.png" name="rowid">
</form>

# 'Edit'选中的一个文件
<form id="action_form" style="display: none" method="POST" action="/admin/fileadmin/action/">
  <input id="action" type="hidden" name="action" value="edit">
  <input class="action-checkbox" type="checkbox" value="1.png" name="rowid">
</form>

总结一下,当我们点击下拉菜单中的菜单项(Delete,Edit),本地JavaScript代码会弹出确认框(假设有确认信息),然后提交一个表单给/admin/fileadmin/action/,请求处理函数action_view()根据表单类型再调用不同的action处理函数,最后返回一个页面。

Flask-Admin字段(列)格式化
在某些情况下,我们需要对模型的某个属性进行格式化。比如,默认情况下,日期时间显示出来会比较长,这时可能需要只显示月和日,这时候,列格式化就派上用场了。

比如,如果你要显示双倍的价格,你可以这样做:


class MyModelView(BaseModelView):
  column_formatters = dict(price=lambda v, c, m, p: m.price*2)

或者在Jinja2模板中使用宏:


from flask.ext.admin.model.template import macro

class MyModelView(BaseModelView):
  column_formatters = dict(price=macro('render_price'))

# in template
{% macro render_price(model, column) %}
  {{ model.price * 2 }}
{% endmacro %}

回调函数模型:


def formatter(view, context, model, name):
  # `view` is current administrative view
  # `context` is instance of jinja2.runtime.Context
  # `model` is model instance
  # `name` is property name
  pass

正好和上面的v, c, m, p相对应。



相关阅读 :
Flask的图形化管理界面搭建框架Flask-Admin的使用教程
Flask框架中@app.route的用法教程
Python的Flask框架中Flask-Admin库的简单入门指引
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