Source code for panel.template.base

Templates allow multiple Panel objects to be embedded into custom HTML
from __future__ import annotations

import os
import sys
import uuid

from functools import partial
from pathlib import Path, PurePath
from typing import (
    IO, TYPE_CHECKING, Any, ClassVar, Dict, List, Literal, Optional, Tuple,

import jinja2
import param

from bokeh.document.document import Document
from bokeh.models import LayoutDOM
from bokeh.settings import settings as _settings
from pyviz_comms import JupyterCommManager as _JupyterCommManager

from ..config import _base_config, config, panel_extension
from import init_doc
from import add_to_doc
from import render_template
from import NotificationArea
from import (
    BUNDLE_DIR, CDN_DIST, ResourceComponent, _env, component_resource_path,
    get_dist_path, loading_css, parse_template, resolve_custom_path,
from import save
from import curdoc_locked, state
from ..layout import Column, GridSpec, ListLike
from ..models.comm_manager import CommManager
from ..pane import (
    HTML, HoloViews, Str, panel as _panel,
from ..pane.image import ImageBase
from ..reactive import ReactiveHTML
from ..theme.base import (
    THEMES, DefaultTheme, Design, Theme,
from ..util import isurl
from ..viewable import (
    MimeRenderMixin, Renderable, ServableMixin, Viewable,
from ..widgets import Button
from ..widgets.indicators import BooleanIndicator, LoadingSpinner

    from bokeh.model import Model
    from bokeh.server.contexts import BokehSessionContext
    from jinja2 import Template as _Template
    from pyviz_comms import Comm

    from import Location
    from import ResourcesType

_server_info: str = (
    '<b>Running server:</b> <a target="_blank" href="https://localhost:{port}">'

FAVICON_URL: str = "/static/extensions/panel/images/favicon.ico"

[docs]class BaseTemplate(param.Parameterized, MimeRenderMixin, ServableMixin, ResourceComponent): config = param.ClassSelector(default=_base_config(), class_=_base_config, constant=True, doc=""" Configuration object declaring custom CSS and JS files to load specifically for this template.""") design = param.ClassSelector(class_=Design, default=Design, is_instance=False, instantiate=False, doc=""" A Design applies themes to a template.""") location = param.Boolean(default=False, doc=""" Whether to add a Location component to this Template. Note if this is set to true, the Jinja2 template must either insert all available roots or explicitly embed the location root with : {{ embed(roots.location) }}.""") theme = param.ClassSelector(class_=Theme, default=DefaultTheme, constant=True, is_instance=False, instantiate=False) # Dictionary of property overrides by Viewable type modifiers: ClassVar[Dict[Type[Viewable], Dict[str, Any]]] = {} ############# # Resources # ############# # pathlib.Path pointing to local CSS file(s) _css: ClassVar[Path | str | List[Path | str] | None] = None # pathlib.Path pointing to local JS file(s) _js: ClassVar[Path | str | List[Path | str] | None] = None # External resources _resources: ClassVar[Dict[str, Dict[str, str]]] = { 'css': {}, 'js': {}, 'js_modules': {}, 'tarball': {} } __abstract = True def __init__( self, template: str | _Template, items=None, nb_template: Optional[str | _Template] = None, **params ): config_params = { p: v for p, v in params.items() if p in _base_config.param } super().__init__(**{ p: v for p, v in params.items() if p not in _base_config.param or p == 'name' }) self.config.param.update(config_params) if isinstance(template, str): self._code: str | None = template self.template = _env.from_string(template) else: self._code = None self.template = template if isinstance(nb_template, str): self.nb_template = _env.from_string(nb_template) else: self.nb_template = nb_template or self.template self._render_items: Dict[str, Tuple[Renderable, List[str]]] = {} self._render_variables: Dict[str, Any] = {} self._documents: List[Document] = [] self._server = None self._layout = self._build_layout() self._setup_design() @param.depends('design', watch=True) def _setup_design(self): self._design = def _update_vars(self, *args) -> None: self._render_variables['template_resources'] = self.resolve_resources() def _build_layout(self) -> Column: str_repr = Str(repr(self)) server_info = HTML('') button = Button(name='Launch server') def launch(event): if self._server: = 'Launch server' server_info.object = '' self._server.stop() self._server = None else: = 'Stop server' self._server = self._get_server(start=True, show=True) server_info.object = _server_info.format(port=self._server.port), 'clicks') return Column(str_repr, server_info, button) def __repr__(self) -> str: spacer = '\n ' objs = spacer.join([ f'[{name}] {obj.__repr__(1)}' # type: ignore for name, (obj, _) in self._render_items.items() if not name.startswith('_') ]) return f'{type(self).__name__}{spacer}{objs}' def _apply_root(self, name: str, model: Model, tags: List[str]) -> None: pass def _server_destroy(self, session_context: BokehSessionContext): doc = session_context._document if doc in state._templates: del state._templates[doc] self._documents.remove(doc) def _init_doc( self, doc: Optional[Document] = None, comm: Optional[Comm] = None, title: Optional[str] = None, notebook: bool = False, location: bool | Location=True ): # Initialize document document: Document = doc or curdoc_locked() document = init_doc(document) self._documents.append(document) if document not in state._templates: state._templates[document] = self if location and self.location: self._add_location(document, location) document.on_session_destroyed(state._destroy_session) # type: ignore document.on_session_destroyed(self._server_destroy) # type: ignore if title or document.title == 'Bokeh Application': title = title or 'Panel Application' document.title = title # Initialize fake root. This is needed to ensure preprocessors # which assume that all models are owned by a single root can # link objects across multiple roots in a template. col = Column() preprocess_root = col.get_root(document, comm, preprocess=False) col._hooks.append(self._design._apply_hooks) ref = preprocess_root.ref['id'] # Add all render items to the document objs, models = [], [] sizing_modes = {} for name, (obj, tags) in self._render_items.items(): # Render root without pre-processing model = obj.get_root(document, comm, preprocess=False) = name model.tags = model.tags + [tag for tag in tags if tag not in model.tags] mref = model.ref['id'] if isinstance(model, LayoutDOM): sizing_modes[mref] = model.sizing_mode if self._design._apply_hooks not in obj._hooks: obj._hooks.append(self._design._apply_hooks) # Alias model ref with the fake root ref to ensure that # pre-processor correctly operates on fake root for sub in submodel = sub._models.get(mref) if submodel is None: continue sub._models[ref] = submodel if isinstance(sub, HoloViews) and mref in sub._plots: sub._plots[ref] = sub._plots.get(mref) # Apply any template specific hooks to root self._apply_root(name, model, tags) # Add document obj._documents[document] = model objs.append(obj) models.append(model) add_to_doc(model, document, hold=bool(comm)) document.on_session_destroyed(obj._server_destroy) # type: ignore # Here we ensure that the preprocessor is run across all roots # and set up session cleanup hooks for the fake root. state._fake_roots.append(ref) # Ensure no update is run state._views[ref] = (col, preprocess_root, document, comm) col.objects = objs preprocess_root.children[:] = models preprocess_root.document = document self._design.apply(col, preprocess_root, isolated=False) col._preprocess(preprocess_root) col._documents[document] = preprocess_root document.on_session_destroyed(col._server_destroy) # type: ignore # Apply the jinja2 template and update template variables if notebook: document.template = self.nb_template else: document.template = self.template self._update_vars() document._template_variables['sizing_modes'] = sizing_modes document._template_variables.update(self._render_variables) return document def _repr_mimebundle_( self, include=None, exclude=None ) -> Tuple[Dict[str, str], Dict[str, Dict[str, str]]] | None: loaded = panel_extension._loaded if not loaded and 'holoviews' in sys.modules: import holoviews as hv loaded = hv.extension._loaded if not loaded: param.main.param.warning( 'Displaying Panel objects in the notebook requires ' 'the panel extension to be loaded. Ensure you run ' 'pn.extension() before displaying objects in the ' 'notebook.' ) return None try: assert get_ipython().kernel is not None # type: ignore # noqa state._comm_manager = _JupyterCommManager except Exception: pass from IPython.display import display doc = Document() comm = state._comm_manager.get_server_comm() self._init_doc(doc, comm, notebook=True) ref = doc.roots[0].ref['id'] manager = CommManager(, plot_id=ref, name='comm_manager' ) client_comm = state._comm_manager.get_client_comm( on_msg=partial(self._on_msg, ref, manager), on_error=partial(self._on_error, ref), on_stdout=partial(self._on_stdout, ref) ) manager.client_comm_id = doc.add_root(manager) if config.console_output != 'disable': handle = display(display_id=uuid.uuid4().hex) state._handles[ref] = (handle, []) return render_template(doc, comm, manager) #---------------------------------------------------------------- # Public API #----------------------------------------------------------------
[docs] def resolve_resources(self, cdn: bool | Literal['auto'] = 'auto') -> ResourcesType: """ Resolves the resources required for this template component. Arguments --------- cdn: bool | Literal['auto'] Whether to load resources from CDN or local server. If set to 'auto' value will be automatically determine based on global settings. Returns ------- Dictionary containing JS and CSS resources. """ cls = type(self) resource_types = super().resolve_resources(cdn=cdn) js_files = resource_types['js'] js_modules = resource_types['js_modules'] css_files = resource_types['css'] raw_css = resource_types['raw_css'] clsname = cls.__name__ name = clsname.lower() dist_path = get_dist_path(cdn=cdn) raw_css.extend(list(self.config.raw_css) + [loading_css( config.loading_spinner, config.loading_color, config.loading_max_height )]) for rname, res in self._design.resolve_resources(cdn).items(): if isinstance(res, dict): resource_types[rname].update(res) else: resource_types[rname] += [ r for r in res if res not in resource_types[rname] ] for rname, js in self.config.js_files.items(): if '//' not in js and state.rel_path: js = f'{state.rel_path}/{js}' js_files[rname] = js for rname, js in self.config.js_modules.items(): if '//' not in js and state.rel_path: js = f'{state.rel_path}/{js}' js_modules[rname] = js for i, css in enumerate(list(self.config.css_files)): if '//' not in css and state.rel_path: css = f'{state.rel_path}/{css}' css_files[f'config_{i}'] = css # CSS files base_css = self._css if not isinstance(base_css, list): base_css = [base_css] if base_css else [] for css in base_css: tmpl_name = name for scls in cls.__mro__[1:]: if not issubclass(scls, BaseTemplate): continue elif scls._css is None: break tmpl_css = scls._css if isinstance(scls._css, list) else [scls._css] if css in tmpl_css: tmpl_name = scls.__name__.lower() css_file = os.path.basename(css) if (BUNDLE_DIR / tmpl_name / css_file).is_file(): css_files[f'base_{css_file}'] = dist_path + f'bundled/{tmpl_name}/{css_file}' elif isurl(css): css_files[f'base_{css_file}'] = css elif resolve_custom_path(self, css): css_files[f'base_{css_file}' ] = component_resource_path(self, '_css', css) # JS files base_js = self._js if not isinstance(base_js, list): base_js = [base_js] if base_js else [] for js in base_js: tmpl_name = name for cls in type(self).__mro__[1:-5]: if not issubclass(cls, BaseTemplate): continue elif cls._js is None: break tmpl_js = cls._js if isinstance(cls._js, list) else [cls._js] if js in tmpl_js: tmpl_name = cls.__name__.lower() js_name = os.path.basename(js) if (BUNDLE_DIR / tmpl_name / js_name).is_file(): js_files[f'base_{js_name}'] = dist_path + f'bundled/{tmpl_name}/{js_name}' elif isurl(js): js_files[f'base_{js_name}'] = js elif resolve_custom_path(self, js): js_files[f'base_{js_name}'] = component_resource_path(self, '_js', js) return resource_types
[docs] def save( self, filename: str | os.PathLike | IO, title: Optional[str] = None, resources=None, embed: bool = False, max_states: int = 1000, max_opts: int = 3, embed_json: bool = False, json_prefix: str='', save_path: str='./', load_path: Optional[str] = None ) -> None: """ Saves Panel objects to file. Arguments --------- filename: string or file-like object Filename to save the plot to title: string Optional title for the plot resources: bokeh resources One of the valid bokeh.resources (e.g. CDN or INLINE) embed: bool Whether the state space should be embedded in the saved file. max_states: int The maximum number of states to embed max_opts: int The maximum number of states for a single widget embed_json: boolean (default=True) Whether to export the data to json files json_prefix: str (default='') Prefix for the auto-generated json directory save_path: str (default='./') The path to save json files to load_path: str (default=None) The path or URL the json files will be loaded from. """ if embed: raise ValueError("Embedding is not yet supported on Template.") return save( self, filename, title, resources, self.template, self._render_variables, embed, max_states, max_opts, embed_json, json_prefix, save_path, load_path )
[docs] def server_doc( self, doc: Optional[Document] = None, title: str = None, location: bool | Location = True ) -> Document: """ Returns a servable bokeh Document with the panel attached Arguments --------- doc : bokeh.Document (optional) The Bokeh Document to attach the panel to as a root, defaults to title : str A string title to give the Document location : boolean or Whether to create a Location component to observe and set the URL location. Returns ------- doc : bokeh.Document The Bokeh document the panel was attached to """ return self._init_doc(doc, title=title, location=location)
[docs] def servable( self, title: Optional[str] = None, location: bool | 'Location' = True, area: str = 'main', target: Optional[str] = None ) -> 'BaseTemplate': """ Serves the template and returns self to allow it to display itself in a notebook context. Arguments --------- title : str A string title to give the Document (if served as an app) location : boolean or Whether to create a Location component to observe and set the URL location. area: str (deprecated) The area of a template to add the component too. Only has an effect if pn.config.template has been set. target: str Target area to write to. If a template has been configured on pn.config.template this refers to the target area in the template while in pyodide this refers to the ID of the DOM node to write to. Returns ------- The template """ if curdoc_locked().session_context and config.template: raise RuntimeError( 'Cannot mark template as servable if a global template ' 'is defined. Either explicitly construct a template and ' 'serve it OR set `pn.config.template`, whether directly ' 'or via `pn.extension(template=...)`, not both.' ) return super().servable(title, location, area, target)
[docs] def select(self, selector=None): """ Iterates over the Template and any potential children in the applying the Selector. Arguments --------- selector: type or callable or None The selector allows selecting a subset of Viewables by declaring a type or callable function to filter by. Returns ------- viewables: list(Viewable) """ objects = [] for obj, _ in self._render_items.values(): objects += return objects
[docs]class TemplateActions(ReactiveHTML): """ A component added to templates that allows triggering events such as opening and closing a modal. """ open_modal = param.Integer(default=0) close_modal = param.Integer(default=0) _template: ClassVar[str] = "" _scripts: ClassVar[Dict[str, List[str] | str]] = { 'open_modal': ["document.getElementById('pn-Modal').style.display = 'block'"], 'close_modal': ["document.getElementById('pn-Modal').style.display = 'none'"], }
[docs]class BasicTemplate(BaseTemplate): """ BasicTemplate provides a baseclass for templates with a basic organization including a header, sidebar and main area. Unlike the more generic Template class these default templates make it easy for a user to generate an application with a polished look and feel without having to write any Jinja2 template themselves. """ busy_indicator = param.ClassSelector(default=LoadingSpinner(width=20, height=20), class_=BooleanIndicator, constant=True, allow_None=True, doc=""" Visual indicator of application busy state.""") collapsed_sidebar = param.Selector(default=False, constant=True, doc=""" Whether the sidebar (if present) is initially collapsed.""") header = param.ClassSelector(class_=ListLike, constant=True, doc=""" A list-like container which populates the header bar.""") main = param.ClassSelector(class_=ListLike, constant=True, doc=""" A list-like container which populates the main area.""") main_max_width = param.String(default="", doc=""" The maximum width of the main area. For example '800px' or '80%'. If the string is '' (default) no max width is set.""") sidebar = param.ClassSelector(class_=ListLike, constant=True, doc=""" A list-like container which populates the sidebar.""") sidebar_width = param.Integer(default=330, doc=""" The width of the sidebar in pixels. Default is 330.""") modal = param.ClassSelector(class_=ListLike, constant=True, doc=""" A list-like container which populates the modal""") notifications = param.ClassSelector(class_=NotificationArea, constant=True, doc=""" The NotificationArea instance attached to this template. Automatically added if config.notifications is set, but may also be provided explicitly.""") logo = param.String(doc=""" URI of logo to add to the header (if local file, logo is base64 encoded as URI). Default is '', i.e. not shown.""") favicon = param.String(default=FAVICON_URL, doc=""" URI of favicon to add to the document head (if local file, favicon is base64 encoded as URI).""") title = param.String(default="Panel Application", doc=""" A title to show in the header. Also added to the document head meta settings and as the browser tab title.""") site = param.String(default="", doc=""" Name of the site. Will be shown in the header and link to the 'site_url'. Default is '', i.e. not shown.""") site_url = param.String(default="/", doc=""" Url of the site and logo. Default is '/'.""") manifest = param.String(default=None, doc=""" Manifest to add to site.""") meta_description = param.String(doc=""" A meta description to add to the document head for search engine optimization. For example 'P.A. Nelson'.""") meta_keywords = param.String(doc=""" Meta keywords to add to the document head for search engine optimization.""") meta_author = param.String(doc=""" A meta author to add to the the document head for search engine optimization. For example 'P.A. Nelson'.""") meta_refresh = param.String(doc=""" A meta refresh rate to add to the document head. For example '30' will instruct the browser to refresh every 30 seconds. Default is '', i.e. no automatic refresh.""") meta_viewport = param.String(doc=""" A meta viewport to add to the header.""") base_url = param.String(doc=""" Specifies the base URL for all relative URLs in a page. Default is '', i.e. not the domain.""") base_target = param.ObjectSelector(default="_self", objects=["_blank", "_self", "_parent", "_top"], doc=""" Specifies the base Target for all relative URLs in a page.""") header_background = param.String(doc=""" Optional header background color override.""") header_color = param.String(doc=""" Optional header text color override.""") location = param.Boolean(default=True, readonly=True) _actions = param.ClassSelector(default=TemplateActions(), class_=TemplateActions) ############# # Resources # ############# # pathlib.Path pointing to local Jinja2 template _template: ClassVar[Path | None] = None __abstract = True def __init__(self, **params): tmpl_string = self._template.read_text(encoding='utf-8') try: template = _env.get_template(str(self._template.relative_to(Path(__file__).parent))) except jinja2.exceptions.TemplateNotFound: template = parse_template(tmpl_string) if 'header' not in params: params['header'] = ListLike() else: params['header'] = self._get_params(params['header'], self.param.header.class_) if 'main' not in params: params['main'] = ListLike() else: params['main'] = self._get_params(params['main'], self.param.main.class_) if 'sidebar' not in params: params['sidebar'] = ListLike() else: params['sidebar'] = self._get_params(params['sidebar'], self.param.sidebar.class_) if 'modal' not in params: params['modal'] = ListLike() else: params['modal'] = self._get_params(params['modal'], self.param.modal.class_) if 'theme' in params: if isinstance(params['theme'], str): params['theme'] = THEMES[params['theme']] else: params['theme'] = THEMES[config.theme] if 'favicon' in params and isinstance(params['favicon'], PurePath): params['favicon'] = str(params['favicon']) if 'notifications' not in params and config.notifications: params['notifications'] = state.notifications if state.curdoc else NotificationArea() super().__init__(template=template, **params) self._js_area = HTML(margin=0, width=0, height=0) if 'embed(roots.js_area)' in tmpl_string: self._render_items['js_area'] = (self._js_area, []) if 'embed(roots.actions)' in tmpl_string: self._render_items['actions'] = (self._actions, []) if 'embed(roots.notifications)' in tmpl_string and self.notifications: self._render_items['notifications'] = (self.notifications, []) self._render_variables['notifications'] = True if config.browser_info and 'embed(roots.browser_info)' in tmpl_string and state.browser_info: self._render_items['browser_info'] = (state.browser_info, []) self._render_variables['browser_info'] = True self._update_busy(), ['objects']), ['objects']), ['objects']), ['objects']) self.main.param.trigger('objects') self.sidebar.param.trigger('objects') self.header.param.trigger('objects') self.modal.param.trigger('objects') def _init_doc( self, doc: Optional[Document] = None, comm: Optional['Comm'] = None, title: Optional[str]=None, notebook: bool = False, location: bool | Location = True ) -> Document: title = self.title if self.title != self.param.title.default else title if self.busy_indicator: state.sync_busy(self.busy_indicator) document = super()._init_doc(doc, comm, title, notebook, location) if self.notifications: state._notifications[document] = self.notifications if self._design.theme.bokeh_theme: document.theme = self._design.theme.bokeh_theme return document def _update_vars(self, *args) -> None: super()._update_vars(*args) self._render_variables['app_title'] = self.title self._render_variables['meta_name'] = self.title self._render_variables['site_title'] = self._render_variables['site_url'] = self.site_url self._render_variables['manifest'] = self.manifest self._render_variables['meta_description'] = self.meta_description self._render_variables['meta_keywords'] = self.meta_keywords self._render_variables['meta_author'] = self.meta_author self._render_variables['meta_refresh'] = self.meta_refresh self._render_variables['meta_viewport'] = self.meta_viewport self._render_variables['base_url'] = self.base_url self._render_variables['base_target'] = self.base_target if os.path.isfile(self.logo): img = _panel(self.logo) if not isinstance(img, ImageBase): raise ValueError(f"Could not determine file type of logo: {self.logo}.") logo = img._b64(img._data(img.object)) else: logo = self.logo if os.path.isfile(self.favicon): img = _panel(self.favicon) if not isinstance(img, ImageBase): raise ValueError(f"Could not determine file type of favicon: {self.favicon}.") favicon = img._b64(img._data(img.object)) else: if _settings.resources(default='server') == 'cdn' and self.favicon == FAVICON_URL: favicon = CDN_DIST + "images/favicon.ico" else: favicon = self.favicon self._render_variables['app_logo'] = logo self._render_variables['app_favicon'] = favicon self._render_variables['app_favicon_type'] = self._get_favicon_type(self.favicon) self._render_variables['header_background'] = self.header_background self._render_variables['header_color'] = self.header_color self._render_variables['main_max_width'] = self.main_max_width self._render_variables['sidebar_width'] = self.sidebar_width self._render_variables['theme'] = self._design.theme self._render_variables['collapsed_sidebar'] = self.collapsed_sidebar def _update_busy(self) -> None: if self.busy_indicator: self._render_items['busy_indicator'] = (self.busy_indicator, []) elif 'busy_indicator' in self._render_items: del self._render_items['busy_indicator'] self._render_variables['busy'] = self.busy_indicator is not None def _update_render_items(self, event: param.parameterized.Event) -> None: if event.obj is self and == 'busy_indicator': return self._update_busy() if event.obj is self.main: tag = 'main' elif event.obj is self.sidebar: tag = 'nav' elif event.obj is self.header: tag = 'header' elif event.obj is self.modal: tag = 'modal' old = event.old if isinstance(event.old, list) else list(event.old.values()) for obj in old: ref = f'{tag}-{str(id(obj))}' if ref in self._render_items: del self._render_items[ref] new = if isinstance(, list) else if self._design.theme.bokeh_theme: for o in new: if o in old: continue for hvpane in hvpane.theme = self._design.theme.bokeh_theme labels = {} for obj in new: ref = f'{tag}-{str(id(obj))}' if labels[ref] = 'Content' else: labels[ref] = self._render_items[ref] = (obj, [tag]) tags = [tags for _, tags in self._render_items.values()] self._render_variables['nav'] = any('nav' in ts for ts in tags) self._render_variables['header'] = any('header' in ts for ts in tags) self._render_variables['root_labels'] = labels def _server_destroy(self, session_context: BokehSessionContext): super()._server_destroy(session_context) if not self._documents and self.busy_indicator in state._indicators: state._indicators.remove(self.busy_indicator)
[docs] def open_modal(self) -> None: """ Opens the modal area """ self._actions.open_modal += 1
[docs] def close_modal(self) -> None: """ Closes the modal area """ self._actions.close_modal += 1
@staticmethod def _get_favicon_type(favicon) -> str: if not favicon: return "" elif favicon.endswith(".png"): return "image/png" elif favicon.endswith("jpg"): return "image/jpg" elif favicon.endswith("gif"): return "image/gif" elif favicon.endswith("svg"): return "image/svg" elif favicon.endswith("ico"): return "image/x-icon" else: raise ValueError("favicon type not supported.") @staticmethod def _get_params(value, class_): if isinstance(value, class_): return value if isinstance(value, tuple): value = [*value] elif not isinstance(value, list): value = [value] # Important to fx. convert @param.depends functions value = [_panel(item) for item in value] if class_ is ListLike: return ListLike(objects=value) if class_ is GridSpec: grid = GridSpec(ncols=12, mode='override') for index, item in enumerate(value): grid[index, :]=item return grid return value
[docs]class Template(BaseTemplate): """ A Template is a high-level component to render multiple Panel objects into a single HTML document defined through a Jinja2 template. The Template object is given a Jinja2 template and then allows populating this template by adding Panel objects, which are given unique names. These unique names may then be referenced in the template to insert the rendered Panel object at a specific location. For instance, given a Jinja2 template that defines roots A and B like this: <div> {{ embed(roots.A) }} </div> <div> {{ embed(roots.B) }} </div> We can then populate the template by adding panel 'A' and 'B' to the Template object: template.add_panel('A', pn.panel('A')) template.add_panel('B', pn.panel('B')) Once a template has been fully populated it can be rendered using the same API as other Panel objects. Note that all roots that have been declared using the {{ embed(roots.A) }} syntax in the Jinja2 template must be defined when rendered. Since embedding complex CSS frameworks inside a notebook can have undesirable side-effects and a notebook does not afford the same amount of screen space a Template may given separate template and nb_template objects. This allows for different layouts when served as a standalone server and when used in the notebook. """ def __init__( self, template: str | _Template, nb_template: str | _Template | None = None, items: Optional[Dict[str, Any]] = None, **params ): super().__init__(template=template, nb_template=nb_template, items=items, **params) items = {} if items is None else items for name, item in items.items(): self.add_panel(name, item) #---------------------------------------------------------------- # Public API #----------------------------------------------------------------
[docs] def add_panel(self, name: str, panel: Viewable, tags: List[str] = []) -> None: """ Add panels to the Template, which may then be referenced by the given name using the jinja2 embed macro. Arguments --------- name : str The name to refer to the panel by in the template panel : panel.Viewable A Panel component to embed in the template. """ if name in self._render_items: raise ValueError('The name %s has already been used for ' 'another panel. Ensure each panel ' 'has a unique name by which it can be ' 'referenced in the template.' % name) self._render_items[name] = (_panel(panel), tags) self._layout[0].object = repr(self) # type: ignore
[docs] def add_variable(self, name: str, value: Any) -> None: """ Add parameters to the template, which may then be referenced by the given name in the Jinja2 template. Arguments --------- name : str The name to refer to the panel by in the template value : object Any valid Jinja2 variable type. """ if name in self._render_variables: raise ValueError('The name %s has already been used for ' 'another variable. Ensure each variable ' 'has a unique name by which it can be ' 'referenced in the template.' % name) self._render_variables[name] = value