bokeh.application.handlers.handler (original) (raw)
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 themodify_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)Provide a mechanism for Bokeh applications to build up new Bokeh Documents.
modify_document(doc: 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: 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: 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: 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: 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: 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.
static_path() → str | None[source]#
Return a path to app-specific static resources, if applicable.
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.
If the handler fails, may contain a related error message.
property error_detail_: str | None_#
If the handler fails, may contain a traceback or other details.
True if the handler failed to modify the doc