bokeh.application.handlers.handler¶
Provide a base class for Bokeh Application handler classes.
When a Bokeh server session is initiated, the Bokeh server asks the Application
for a new Document to service the session. To do this, the Application first
creates a new empty Document, then it passes this new Document to the
modify_document
method of each of its handlers. When all handlers have
updated the Document, it is used to service the user session.
Below is an example outline of a custom handler that might modify documents based off information in some database:
class DatabaseHandler(Handler):
""" A Bokeh Application handler to initialize Documents from a database
"""
def modify_document(self, doc: Document) -> None:
# do some data base lookup here to generate 'plot'
# add the plot to the document (i.e modify the document)
doc.add_root(plot)
- class Handler[source]¶
Provide a mechanism for Bokeh applications to build up new Bokeh Documents.
Public Data Attributes:
If the handler fails, may contain a related error message.
If the handler fails, may contain a traceback or other details.
True
if the handler failed to modify the docsafe_to_fork
Public Methods:
__init__
()modify_document
(doc)Modify an application document in a specified manner.
on_server_loaded
(server_context)Execute code when the server is first started.
on_server_unloaded
(server_context)Execute code when the server cleanly exits.
on_session_created
(session_context)Execute code when a new session is created.
on_session_destroyed
(session_context)Execute code when a session is destroyed.
process_request
(request)Processes incoming HTTP request returning a dictionary of additional data to add to the session_context.
Return a path to app-specific static resources, if applicable.
url_path
()Returns a default URL path, if applicable.
- modify_document(doc: bokeh.document.document.Document) None [source]¶
Modify an application document in a specified manner.
When a Bokeh server session is initiated, the Bokeh server asks the Application for a new Document to service the session. To do this, the Application first creates a new empty Document, then it passes this Document to the
modify_document
method of each of its handlers. When all handlers have updated the Document, it is used to service the user session.Subclasses must implement this method
- Parameters
doc (Document) – A Bokeh Document to update in-place
- Returns
Document
- on_server_loaded(server_context: bokeh.application.application.ServerContext) None [source]¶
Execute code when the server is first started.
Subclasses may implement this method to provide for any one-time initialization that is necessary after the server starts, but before any sessions are created.
- Parameters
server_context (ServerContext) –
- on_server_unloaded(server_context: bokeh.application.application.ServerContext) None [source]¶
Execute code when the server cleanly exits. (Before stopping the server’s
IOLoop
.)Subclasses may implement this method to provide for any one-time tear down that is necessary before the server exits.
- Parameters
server_context (ServerContext) –
Warning
In practice this code may not run, since servers are often killed by a signal.
- async on_session_created(session_context: bokeh.application.application.SessionContext) None [source]¶
Execute code when a new session is created.
Subclasses may implement this method to provide for any per-session initialization that is necessary before
modify_doc
is called for the session.- Parameters
session_context (SessionContext) –
- async on_session_destroyed(session_context: bokeh.application.application.SessionContext) None [source]¶
Execute code when a session is destroyed.
Subclasses may implement this method to provide for any per-session tear-down that is necessary when sessions are destroyed.
- Parameters
session_context (SessionContext) –
- process_request(request: tornado.httputil.HTTPServerRequest) Dict[str, Any] [source]¶
Processes incoming HTTP request returning a dictionary of additional data to add to the session_context.
- Parameters
request – HTTP request
- Returns
A dictionary of JSON serializable data to be included on the session context.
- url_path() str | None [source]¶
Returns a default URL path, if applicable.
Handlers subclasses may optionally implement this method, to inform the Bokeh application what URL it should be installed at.
If multiple handlers specify
url_path
the Application will use the value from the first handler in its list of handlers.