mirror of
https://github.com/pgadmin-org/pgadmin4.git
synced 2024-07-04 11:33:52 -05:00
216 lines
9.0 KiB
ReStructuredText
216 lines
9.0 KiB
ReStructuredText
.. _code_overview:
|
|
|
|
**********************
|
|
`Code Overview`:index:
|
|
**********************
|
|
|
|
The bulk of pgAdmin is a Python web application written using the Flask framework
|
|
on the backend, and HTML5 with CSS3,ReactJS on the front end. A
|
|
desktop runtime is also included for users that prefer a desktop application to
|
|
a web application, which is written using Electron.
|
|
|
|
Runtime
|
|
*******
|
|
|
|
The runtime is based on Electron which integrates a browser and the Python server
|
|
creating a standalone application. The source code can be found in the
|
|
**/runtime** directory in the source tree.
|
|
|
|
Web Application
|
|
***************
|
|
|
|
The web application forms the bulk of pgAdmin and can be found in the **/web**
|
|
directory in the source tree. The main file is **pgAdmin4.py** which can be used
|
|
to run the built-in standalone web server, or as a WSGI application for production
|
|
use.
|
|
|
|
Configuration
|
|
=============
|
|
|
|
The core application configuration is found in **config.py**. This file includes
|
|
all configurable settings for the application, along with descriptions of their
|
|
use. It is essential that various settings are configured prior to deployment on
|
|
a web server; these can be overridden in **config_local.py** or
|
|
**config_system.py** (see the :ref:`config.py <config_py>` documentation) to
|
|
avoid modifying the main configuration file.
|
|
|
|
User Settings
|
|
=============
|
|
|
|
When running in desktop mode, pgAdmin has a single, default user account that is
|
|
used for the desktop user. When running in server mode, there may be unlimited
|
|
users who are required to login prior to using the application. pgAdmin utilised
|
|
the **Flask-Security** module to manage application security and users, and
|
|
provides options for self-service password reset and password changes etc.
|
|
|
|
Whether in desktop or server mode, each user's settings are stored in a SQLite
|
|
OR external database which is also used to store the user accounts. This is initially
|
|
created using the **setup.py** script which will create the database file and
|
|
schema within it, and add the first user account (with administrative
|
|
privileges) and a default server group for them. A **settings** table is also
|
|
used to store user configuration settings in a key-value fashion. Although not
|
|
required, setting keys (or names) are typically formatted using forward slashes
|
|
to artificially namespace values, much like the pgAdmin 3 settings files on Linux
|
|
or Mac.
|
|
|
|
Note that the local configuration must be setup prior to **setup.py** being run.
|
|
The local configuration will determine how the script sets up the database,
|
|
particularly with regard to desktop vs. server mode.
|
|
|
|
pgAdmin Core
|
|
************
|
|
|
|
The heart of pgAdmin is the **pgadmin** package. This contains the globally
|
|
available HTML templates used by the Jinja engine, as well as any global static
|
|
files such as images, Javascript and CSS files that are used in multiple modules.
|
|
|
|
The work of the package is handled in it's constructor, **__init__.py**. This
|
|
is responsible for setting up logging and authentication, dynamically loading
|
|
other modules, and a few other tasks.
|
|
|
|
Modules
|
|
*******
|
|
|
|
Units of functionality are added to pgAdmin through the addition of modules.
|
|
Theses are Python object instance of classes, inherits the
|
|
PgAdminModule class (a Flask Blueprint implementation), found in
|
|
**web/pgadmin/utils.py**. It provide various hook points for other modules
|
|
to utilise (primarily the default module - the browser).
|
|
|
|
To be recognised as a module, a Python package must be created. This must:
|
|
|
|
1) Be placed within the **web/pgadmin/** directory, and
|
|
2) Implements pgadmin.utils.PgAdminModule class
|
|
3) An instance variable (generally - named **blueprint**) representing that
|
|
particular class in that package.
|
|
|
|
Each module may define a **template** and **static** directory for the Blueprint
|
|
that it implements. To avoid name collisions, templates should be stored under
|
|
a directory within the specified template directory, named after the module itself.
|
|
For example, the **browser** module stores it's templates in
|
|
**web/pgadmin/browser/templates/browser/**. This does not apply to static files
|
|
which may omit the second module name.
|
|
|
|
In addition to defining the Blueprint, the **views** module is typically
|
|
responsible for defining all the views that will be rendered in response to
|
|
client requests, we must provide a REST API url(s) for these views. These must
|
|
include appropriate route and security decorators. Take a look at the NodeView
|
|
class, which uses the same approach as Flask's MethodView, it can be found in
|
|
**web/pgadmin/browser/utils.py**. This specific class is used by browser nodes
|
|
for creating REST API url(s) for different operation on them. i.e. list, create,
|
|
update, delete, fetch children, get
|
|
statistics/reversed SQL/dependencies/dependents list for that node, etc. We can
|
|
use the same class for other purpose too. You just need to inherit that class,
|
|
and overload the member variables operations, parent_ids, ids, node_type, and
|
|
then register it as node view with PgAdminModule instance.
|
|
|
|
Most pgAdmin modules will also implement the **hooks** provided by the
|
|
PgAdminModule class. This is responsible for providing hook points to integrate
|
|
the module into the rest of the application - for example, a hook might tell
|
|
the caller what CSS files need to be included on the rendered page, or what menu
|
|
options to include and what they should do. Hook points need not exist if they
|
|
are not required. It is the responsibility of the caller to ensure they are
|
|
present before attempting to utilise them.
|
|
|
|
Hooks currently implemented are:
|
|
|
|
.. code-block:: python
|
|
|
|
class MyModule(PgAdminModule):
|
|
"""
|
|
This is class implements the pgadmin.utils.PgAdminModule, and
|
|
implements the hooks
|
|
"""
|
|
|
|
...
|
|
|
|
def get_own_stylesheets(self):
|
|
"""
|
|
Returns:
|
|
list: the stylesheets used by this module, not including any
|
|
stylesheet needed by the submodules.
|
|
"""
|
|
return [url_for('static', 'css/mymodule.css')]
|
|
|
|
def get_own_javascripts(self):
|
|
"""
|
|
Returns:
|
|
list of dict:
|
|
- contains the name (representation for this javascript
|
|
module), path (url for it without .js suffix), deps (array of
|
|
dependents), exports window object by the javascript module,
|
|
and when (would you like to load this javascript), etc
|
|
information for this module, not including any script needed
|
|
by submodules.
|
|
"""
|
|
return [
|
|
{
|
|
'name': 'pgadmin.extension.mymodule',
|
|
'path': url_for('static', filename='js/mymodule'),
|
|
'exports': None,
|
|
'when': 'server'
|
|
}
|
|
]
|
|
|
|
def get_own_menuitems(self):
|
|
"""
|
|
Returns:
|
|
dict: the menuitems for this module, not including
|
|
any needed from the submodules.
|
|
"""
|
|
return {
|
|
'help_items': [
|
|
MenuItem(
|
|
name='mnu_mymodule_help',
|
|
priority=999,
|
|
# We need to create javascript, which registers itself
|
|
# as module
|
|
module="pgAdmin.MyModule",
|
|
callback='about_show',
|
|
icon='fa fa-info-circle',
|
|
label=gettext('About MyModule'
|
|
)
|
|
]
|
|
}
|
|
def get_panels(self):
|
|
"""
|
|
Returns:
|
|
list: a list of panel objects to add implemented in javascript
|
|
module
|
|
"""
|
|
return []
|
|
...
|
|
|
|
|
|
|
|
blueprint = MyModule('mymodule', __name__, static_url_path='/static')
|
|
|
|
pgAdmin Modules may include any additional Python modules that are required to
|
|
fulfill their purpose, as required. They may also reference other dynamically
|
|
loaded modules, but must use the defined hook points and fail gracefully in the
|
|
event that a particular module is not present.
|
|
|
|
Nodes
|
|
*****
|
|
|
|
Nodes are very similar to modules, it represents an individual node or,
|
|
collection object on the object explorer treeview. To recognised as a node module, a
|
|
Python package (along with javascript modules) must be created. This must:
|
|
|
|
1) Be placed within the **web/pgadmin/browser/** directory, and
|
|
2) Implements the BrowserPluginModule, and registers the node view, which
|
|
exposes required the REST APIs
|
|
3) An instance of the class object
|
|
|
|
Front End
|
|
*********
|
|
|
|
pgAdmin uses javascript extensively for the front-end implementation. It uses
|
|
require.js to allow the lazy loading (or, say load only when required),
|
|
ReactJS with CSS and MaterialUI for UI look and feel. We have
|
|
divided each module in small chunks as much as possible. Not all javascript
|
|
modules are required to be loaded (i.e. loading a javascript module for
|
|
database will make sense only when a server node is loaded completely.) Please
|
|
look at the javascript files node.js, browser.js, menu.js, panel.js, etc for
|
|
better understanding of the code.
|