Breadcrumbs#

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import panel as pn
import panel_material_ui as pmui

pn.extension()

The Breadcrumbs component is part of the Menu family of components. Menu components provide a structured way for users to navigate or choose between a series of defined items. In the case of Breadcrumbs, these items represent navigation steps or levels in a hierarchy.

Each item in the Breadcrumbs list is defined by a dictionary with several supported keys:

Item Structure#

Each item can include the following keys:

label (str, required): The text displayed for the breadcrumb item.
href (str, optional): A URL to link to. If provided, the breadcrumb becomes a link.
icon (str, optional): An icon to display next to the label.
avatar (str, optional): An avatar or image to show beside the label.
target (str, optional): A URL to link to. If provided, the breadcrumb becomes a link.

These dictionaries are passed to the component via the items parameter as a list. When one of the items is selected it will be available on the value parameter.

Since only the allowed keys are synced with the frontend, other information can be stored in the item dictionaries.

Parameters:#

Core#

active (boolean): Whether the dialog is visible.
items (list): List of menu items.
value (dict): The currently selected item.

Display#

color (str): The color of the bar, one of ‘default’, ‘primary’, ‘secondary’, ‘success’, ‘info’, ‘warning’, ‘danger’, ‘light’ or ‘dark’.
separator (str): The separator displayed between breadcrumb items.

Styling#

sx (dict): Component level styling API.
theme_config (dict): Theming API.

Methods#

on_click: Registers a callback to be executed when the MenuButton is clicked.
remove_on_click: Removes a callback that was previously registered.

Basic Usage#

Breadcrumbs like all menu components allows selecting between a number of items defined as dictionaries in a list:

items = [
    {'label': 'Documentation', 'icon': 'article'},
    {'label': 'Reference Gallery', 'icon': 'category'},
    {'label': 'Menus', 'icon': 'menu'},
    {'label': 'Breadcrumbs', 'icon': 'grain'},
]

breadcrumbs = pmui.Breadcrumbs(items=items, active=3)

breadcrumbs

The items require a label but may also include other information including an icon or avatar and href and target value to declare a link.

Clicking on a particular item will highlight it and set both active and value parameters:

print(f'Active: {breadcrumbs.active}')
print(f'Value: {breadcrumbs.value}')

Active: 3
Value: {'label': 'Breadcrumbs', 'icon': 'grain'}

Alternatively you may also register on_click handlers:

row = pmui.Column('# Click Events')

breadcrumbs.on_click(row.append)

row

Try clicking on the Breadcrumbs and see the clicked item appear.

Custom Item Keys#

Like all menus the items only sync the allowed keys. This means you can easily store other information in the items, e.g. you can use it to easily select between different views to be displayed:

breadcrumbs = pmui.Breadcrumbs(
    items=[
        {'label': '🏰 Kingdom', 'view': pmui.Typography('# 🏰 Welcome to the Kingdom')},
        {'label': '🌲 Enchanted Forest', 'view': pmui.Typography('# 🌲 You enter the Enchanted Forest...')},
        {'label': '🐉 Dragon\'s Lair', 'view': pmui.Typography('# 🐉 Beware! You approach the Dragon\'s Lair.')},
        {'label': '💎 Treasure Room', 'view': pmui .Typography('# 💎 Congratulations! You found the Treasure.')},
    ],
    active=0,  # Start at the beginning of the journey
    color='warning'
)

pn.Column(
    breadcrumbs,
    breadcrumbs.rx()['view']
)

In the above example we take advantage of the fact that Widget.rx() returns a reactive reference to the value parameter and then access the view on that item. Rendering this expression allows us to control the current view with the menu.

Max Items#

The number of items that are displayed can be limited with the max_items option, any further items are collapsed:

pmui.Breadcrumbs(items=items, active=3, max_items=2)

Separator#

The default separator can be replaced with a custom character:

pmui.Breadcrumbs(items=items, active=3, separator='|')

Color Options#

The color parameter may be used to visually distinguish the selected Breadcrumbs. Available options include “default”, “primary”, “secondary”, “error”, “info”, “success”, “warning”, “light”, “dark”, and “danger”:

The color of the selected breadcrumb can be set:

pmui.FlexBox(*(
    pmui.Breadcrumbs(items=items, color=color, active=3) for color in pmui.Breadcrumbs.param.color.objects
))

API Reference#

Parameters#

The Breadcrumbs menu exposes a number of options which can be changed from both Python and Javascript. Try out the effect of these parameters interactively:

pmui.Breadcrumbs(items=[
    {'label': 'Documentation', 'icon': 'article'},
    {'label': 'Reference Gallery', 'icon': 'category'},
    {'label': 'Menus', 'icon': 'menu'},
    {'label': 'Breadcrumbs', 'icon': 'grain'},
]).api(jslink=True)

References#

Panel Documentation:

How-to guides on interactivity - Learn how to add interactivity to your applications using widgets
Setting up callbacks and links - Connect parameters between components and create reactive interfaces
Declarative UIs with Param - Build parameter-driven applications

Material UI Breadcrumbs:

Material UI Breadcrumbs Reference - Complete documentation for the underlying Material UI component
Material UI Breadcrumbs API - Detailed API reference and configuration options

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