bokeh.application.handlers.function

Provide a Bokeh Application Handler to build up documents by running a specified Python function.

This Handler is not used by the Bokeh server command line tool, but is often useful if users wish to embed the Bokeh server programmatically:

def make_doc(doc: Document):
    # do work to modify the document, add plots, widgets, etc.
    return doc

app = Application(FunctionHandler(make_doc))

server = Server({'/bkapp': app}, io_loop=IOLoop.current())
server.start()

For complete examples of this technique, see examples/howto/server_embed

class FunctionHandler(func: Callable[[Document], None], *, trap_exceptions: bool = False)

A Handler that accepts a plain python function to use for modifying Bokeh Documents.

For example, the following code configures a handler with a function that adds an empty plot to a Document:

def add_empty_plot(doc: Document):
    p = figure(x_range=(0, 10), y_range=(0, 10))
    doc.add_root(p)
    return doc

handler = FunctionHandler(add_empty_plot)

This handler could be configured on an Application, and the Application would run this function every time a new session is created.

Public Data Attributes:

safe_to_fork

Whether it is still safe for the Bokeh server to fork new workers.

Inherited from Handler

error	If the handler fails, may contain a related error message.
error_detail	If the handler fails, may contain a traceback or other details.
failed	True if the handler failed to modify the doc
safe_to_fork	Whether it is still safe for the Bokeh server to fork new workers.

Public Methods:

__init__(func, *[, trap_exceptions])	param func a function to modify and return a Bokeh Document.
modify_document(doc)	Execute the configured func to modify the document.

Inherited from Handler

__init__(func, *[, trap_exceptions])	param func a function to modify and return a Bokeh Document.
modify_document(doc)	Execute the configured func to modify the document.
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.
static_path()	Return a path to app-specific static resources, if applicable.
url_path()	Returns a default URL path, if applicable.

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__init__(func: Callable[[Document], None], *, trap_exceptions: bool = False) → None

Parameters

• func (callable) –

  a function to modify and return a Bokeh Document. The function should have the form:

  def func(doc: Document):
      # modify doc
      return doc
  

  and it should return the passed-in document after making any modifications in-place.

• trap_exceptions (bool) – should exceptions in func be caught and logged or allowed to propagate

modify_document(doc: Document) → None

Execute the configured func to modify the document.

After this method is first executed, safe_to_fork will return False.

property safe_to_fork: bool

Whether it is still safe for the Bokeh server to fork new workers.

False if modify_doc has already been called.