Code Snippets - pgAdmin 4 1.3 documentation
This document contains code for some of the important classes, listed as below:
PgAdminModule ¶
PgAdminModule is inherted from Flask.Blueprint module. This module defines a set of methods, properties and attributes, that every module should implement.
class PgAdminModule(Blueprint):
"""
Base class for every PgAdmin Module.
This class defines a set of method and attributes that
every module should implement.
"""
def __init__(self, name, import_name, **kwargs):
kwargs.setdefault('url_prefix', '/' + name)
kwargs.setdefault('template_folder', 'templates')
kwargs.setdefault('static_folder', 'static')
self.submodules = []
super(PgAdminModule, self).__init__(name, import_name, **kwargs)
def create_module_preference():
# Create preference for each module by default
if hasattr(self, 'LABEL'):
self.preference = Preferences(self.name, self.LABEL)
else:
self.preference = Preferences(self.name, None)
self.register_preferences()
# Create and register the module preference object and preferences for
# it just before the first request
self.before_app_first_request(create_module_preference)
def register_preferences(self):
pass
def register(self, app, options, first_registration=False):
"""
Override the default register function to automagically register
sub-modules at once.
"""
if first_registration:
self.submodules = list(app.find_submodules(self.import_name))
super(PgAdminModule, self).register(app, options, first_registration)
for module in self.submodules:
app.register_blueprint(module)
def get_own_stylesheets(self):
"""
Returns:
list: the stylesheets used by this module, not including any
stylesheet needed by the submodules.
"""
return []
def get_own_messages(self):
"""
Returns:
dict: the i18n messages used by this module, not including any
messages needed by the submodules.
"""
return dict()
def get_own_javascripts(self):
"""
Returns:
list: the javascripts used by this module, not including
any script needed by the submodules.
"""
return []
def get_own_menuitems(self):
"""
Returns:
dict: the menuitems for this module, not including
any needed from the submodules.
"""
return defaultdict(list)
def get_panels(self):
"""
Returns:
list: a list of panel objects to add
"""
return []
@property
def stylesheets(self):
stylesheets = self.get_own_stylesheets()
for module in self.submodules:
stylesheets.extend(module.stylesheets)
return stylesheets
@property
def messages(self):
res = self.get_own_messages()
for module in self.submodules:
res.update(module.messages)
return res
@property
def javascripts(self):
javascripts = self.get_own_javascripts()
for module in self.submodules:
javascripts.extend(module.javascripts)
return javascripts
@property
def menu_items(self):
menu_items = self.get_own_menuitems()
for module in self.submodules:
for key, value in module.menu_items.items():
menu_items[key].extend(value)
menu_items = dict((key, sorted(value, key=attrgetter('priority')))
for key, value in menu_items.items())
return menu_items
NodeView ¶
NodeView class helps exposing basic REST APIs for different operations used by pgAdmin Browser. The basic idea has been taken from the Flask’s MethodView class. Because - we need a lot more operations (not, just CRUD), we can not use it directly.
class NodeView(with_metaclass(MethodViewType, View)):
"""
A PostgreSQL Object has so many operaions/functions apart from CRUD
(Create, Read, Update, Delete):
i.e.
- Reversed Engineered SQL
- Modified Query for parameter while editing object attributes
i.e. ALTER TABLE ...
- Statistics of the objects
- List of dependents
- List of dependencies
- Listing of the children object types for the certain node
It will used by the browser tree to get the children nodes
This class can be inherited to achieve the diffrent routes for each of the
object types/collections.
OPERATION URL HTTP Method Method
---------------+-----------------------------+-------------+--------------
List /obj/[Parent URL]/ GET list
Properties /obj/[Parent URL]/id GET properties
Create /obj/[Parent URL]/ POST create
Delete /obj/[Parent URL]/id DELETE delete
Update /obj/[Parent URL]/id PUT update
SQL (Reversed /sql/[Parent URL]/id GET sql
Engineering)
SQL (Modified /msql/[Parent URL]/id GET modified_sql
Properties)
Statistics /stats/[Parent URL]/id GET statistics
Dependencies /dependency/[Parent URL]/id GET dependencies
Dependents /dependent/[Parent URL]/id GET dependents
Nodes /nodes/[Parent URL]/ GET nodes
Current Node /nodes/[Parent URL]/id GET node
Children /children/[Parent URL]/id GET children
NOTE:
Parent URL can be seen as the path to identify the particular node.
i.e.
In order to identify the TABLE object, we need server -> database -> schema
information.
"""
operations = dict({
'obj': [
{'get': 'properties', 'delete': 'delete', 'put': 'update'},
{'get': 'list', 'post': 'create'}
],
'nodes': [{'get': 'node'}, {'get': 'nodes'}],
'sql': [{'get': 'sql'}],
'msql': [{'get': 'modified_sql'}],
'stats': [{'get': 'statistics'}],
'dependency': [{'get': 'dependencies'}],
'dependent': [{'get': 'dependents'}],
'children': [{'get': 'children'}],
'module.js': [{}, {}, {'get': 'module_js'}]
})
@classmethod
def generate_ops(cls):
cmds = []
for op in cls.operations:
idx = 0
for ops in cls.operations[op]:
meths = []
for meth in ops:
meths.append(meth.upper())
if len(meths) > 0:
cmds.append({
'cmd': op, 'req': (idx == 0),
'with_id': (idx != 2), 'methods': meths
})
idx += 1
return cmds
# Inherited class needs to modify these parameters
node_type = None
# This must be an array object with attributes (type and id)
parent_ids = []
# This must be an array object with attributes (type and id)
ids = []
@classmethod
def get_node_urls(cls):
assert cls.node_type is not None, \
"Please set the node_type for this class ({0})".format(
str(cls.__class__.__name__))
common_url = '/'
for p in cls.parent_ids:
common_url += '<{0}:{1}>/'.format(str(p['type']), str(p['id']))
id_url = None
for p in cls.ids:
id_url = '{0}<{1}:{2}>'.format(common_url if not id_url else id_url,
p['type'], p['id'])
return id_url, common_url
def __init__(self, **kwargs):
self.cmd = kwargs['cmd']
# Check the existance of all the required arguments from parent_ids
# and return combination of has parent arguments, and has id arguments
def check_args(self, **kwargs):
has_id = has_args = True
for p in self.parent_ids:
if p['id'] not in kwargs:
has_args = False
break
for p in self.ids:
if p['id'] not in kwargs:
has_id = False
break
return has_args, has_id and has_args
def dispatch_request(self, *args, **kwargs):
meth = flask.request.method.lower()
if meth == 'head':
meth = 'get'
assert self.cmd in self.operations, \
"Unimplemented command ({0}) for {1}".format(
self.cmd,
str(self.__class__.__name__)
)
has_args, has_id = self.check_args(**kwargs)
assert (self.cmd in self.operations and
(has_id and len(self.operations[self.cmd]) > 0 and
meth in self.operations[self.cmd][0]) or
(not has_id and len(self.operations[self.cmd]) > 1 and
meth in self.operations[self.cmd][1]) or
(len(self.operations[self.cmd]) > 2 and
meth in self.operations[self.cmd][2])), \
"Unimplemented method ({0}) for command ({1}), which {2} an id".format(
meth, self.cmd,
'requires' if has_id else 'does not require'
)
meth = self.operations[self.cmd][0][meth] if has_id else \
self.operations[self.cmd][1][meth] if has_args and \
meth in self.operations[self.cmd][1] else \
self.operations[self.cmd][2][meth]
method = getattr(self, meth, None)
if method is None:
return make_json_response(
status=406,
success=0,
errormsg=gettext(
"Unimplemented method ({0}) for this url ({1})".format(
meth, flask.request.path)
)
)
return method(*args, **kwargs)
@classmethod
def register_node_view(cls, blueprint):
cls.blueprint = blueprint
id_url, url = cls.get_node_urls()
commands = cls.generate_ops()
for c in commands:
if c['with_id']:
blueprint.add_url_rule(
'/{0}{1}'.format(
c['cmd'], id_url if c['req'] else url
),
view_func=cls.as_view(
'{0}{1}'.format(
c['cmd'], '_id' if c['req'] else ''
),
cmd=c['cmd']
),
methods=c['methods']
)
else:
blueprint.add_url_rule(
'/{0}'.format(c['cmd']),
view_func=cls.as_view(
'{0}'.format(c['cmd']), cmd=c['cmd']
),
methods=c['methods']
)
def module_js(self, **kwargs):
"""
This property defines (if javascript) exists for this node.
Override this property for your own logic.
"""
return flask.make_response(
flask.render_template(
"{0}/js/{0}.js".format(self.node_type)
),
200, {'Content-Type': 'application/x-javascript'}
)
def children(self, *args, **kwargs):
"""Build a list of treeview nodes from the child nodes."""
children = []
for module in self.blueprint.submodules:
children.extend(module.get_nodes(*args, **kwargs))
# Return sorted nodes based on label
return make_json_response(
data=sorted(
children, key=lambda c: c['label']
)
)
BaseDriver ¶
class BaseDriver(object):
"""
class BaseDriver(object):
This is a base class for different server types.
Inherit this class to implement different type of database driver
implementation.
(For PostgreSQL/Postgres Plus Advanced Server, we will be using psycopg2)
Abstract Properties:
-------- ----------
* Version (string):
Current version string for the database server
Abstract Methods:
-------- -------
* get_connection(*args, **kwargs)
- It should return a Connection class object, which may/may not be
connected to the database server.
* release_connection(*args, **kwargs)
- Implement the connection release logic
* gc()
- Implement this function to release the connections assigned in the
session, which has not been pinged from more than the idle timeout
configuration.
"""
@abstractproperty
def Version(cls):
pass
@abstractmethod
def get_connection(self, *args, **kwargs):
pass
@abstractmethod
def release_connection(self, *args, **kwargs):
pass
@abstractmethod
def gc(self):
pass
BaseConnection ¶
class BaseConnection(object):
"""
class BaseConnection(object)
It is a base class for database connection. A different connection
drive must implement this to expose abstract methods for this server.
General idea is to create a wrapper around the actual driver
implementation. It will be instantiated by the driver factory
basically. And, they should not be instantiated directly.
Abstract Methods:
-------- -------
* connect(**kwargs)
- Define this method to connect the server using that particular driver
implementation.
* execute_scalar(query, params, formatted_exception_msg)
- Implement this method to execute the given query and returns single
datum result.
* execute_async(query, params, formatted_exception_msg)
- Implement this method to execute the given query asynchronously and returns result.
* execute_void(query, params, formatted_exception_msg)
- Implement this method to execute the given query with no result.
* execute_2darray(query, params, formatted_exception_msg)
- Implement this method to execute the given query and returns the result
as a 2 dimensional array.
* execute_dict(query, params, formatted_exception_msg)
- Implement this method to execute the given query and returns the result
as an array of dict (column name -> value) format.
* connected()
- Implement this method to get the status of the connection. It should
return True for connected, otherwise False
* reset()
- Implement this method to reconnect the database server (if possible)
* transaction_status()
- Implement this method to get the transaction status for this
connection. Range of return values different for each driver type.
* ping()
- Implement this method to ping the server. There are times, a connection
has been lost, but - the connection driver does not know about it. This
can be helpful to figure out the actual reason for query failure.
* _release()
- Implement this method to release the connection object. This should not
be directly called using the connection object itself.
NOTE: Please use BaseDriver.release_connection(...) for releasing the
connection object for better memory management, and connection pool
management.
* _wait(conn)
- Implement this method to wait for asynchronous connection to finish the
execution, hence - it must be a blocking call.
* _wait_timeout(conn, time)
- Implement this method to wait for asynchronous connection with timeout.
This must be a non blocking call.
* poll(formatted_exception_msg)
- Implement this method to poll the data of query running on asynchronous
connection.
* cancel_transaction(conn_id, did=None)
- Implement this method to cancel the running transaction.
* messages()
- Implement this method to return the list of the messages/notices from
the database server.
* rows_affected()
- Implement this method to get the rows affected by the last command
executed on the server.
"""
ASYNC_OK = 1
ASYNC_READ_TIMEOUT = 2
ASYNC_WRITE_TIMEOUT = 3
ASYNC_NOT_CONNECTED = 4
ASYNC_EXECUTION_ABORTED = 5
@abstractmethod
def connect(self, **kwargs):
pass
@abstractmethod
def execute_scalar(self, query, params=None, formatted_exception_msg=False):
pass
@abstractmethod
def execute_async(self, query, params=None, formatted_exception_msg=True):
pass
@abstractmethod
def execute_void(self, query, params=None, formatted_exception_msg=False):
pass
@abstractmethod
def execute_2darray(self, query, params=None, formatted_exception_msg=False):
pass
@abstractmethod
def execute_dict(self, query, params=None, formatted_exception_msg=False):
pass
@abstractmethod
def connected(self):
pass
@abstractmethod
def reset(self):
pass
@abstractmethod
def transaction_status(self):
pass
@abstractmethod
def ping(self):
pass
@abstractmethod
def _release(self):
pass
@abstractmethod
def _wait(self, conn):
pass
@abstractmethod
def _wait_timeout(self, conn, time):
pass
@abstractmethod
def poll(self, formatted_exception_msg=True):
pass
@abstractmethod
def status_message(self):
pass
@abstractmethod
def rows_affected(self):
pass
@abstractmethod
def cancel_transaction(self, conn_id, did=None):
pass