Flask-Admin入门

#flask #web

Flask-Admin是什么？

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；

如何使用

Flask-Admin的文档写得比较简单，单从文档很难理解如何使用，好在作者提供了的很多Example（见源码），基本上照葫芦画瓢即可；

下面就通过分析一些Example代码来学习使用

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：

  1. 将每个view注册为blueprint（Flask里的概念，可以简单理解为模块）
  2. 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。

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