chore: bump dash from 3.3.0 to 4.2.0

[dependabot]

Bumps dash from 3.3.0 to 4.2.0.

Release notes

Sourced from dash's releases.

Dash Version 4.2.0

[4.2.0] - 2026-06-01 - The Freedom Update

This release marks a major milestone for Dash, bringing unprecedented flexibility to how you build and deploy your applications.

🚀 Multiple Backend Support

Dash is no longer tied to Flask. You can now run your Dash apps on FastAPI or Quart, or even bring your own backend implementation:

# FastAPI backendapp=Dash(__name__, backend="fastapi")
Quartbackend (async-native)
app=Dash(name, backend="quart")
OruseanexistingserverfromfastapiimportFastAPIserver=FastAPI()
app=Dash(name, server=server)

Install with pip install dash[fastapi] or pip install dash[quart].

⚡ Websocket Callbacks

Real-time, bidirectional communication is here. Websocket callbacks enable persistent connections for live updates without polling:

@callback(Output("live-output", "children"),Input("trigger", "n_clicks"),websocket=True,persistent=True)deflive_updates(n_clicks):
ws=ctx.websocketwhileTrue:
data=fetch_live_data()
ws.send(Output("live-output", "children", data))
time.sleep(1)

🔓 Relaxed Pattern Matching Rules

MATCH wildcards are now allowed in Input and State even when your Output has no wildcards, making dynamic UIs simpler to build:

@callback(Output("summary", "children"), # Fixed ID outputInput({"type": "item", "index": MATCH}, "value") # MATCH input - now allowed!)defupdate_summary(value):
</tr></table>

... (truncated)

Changelog

Sourced from dash's changelog.

[4.2.0] - 2026-06-01 - The Freedom Update

This release marks a major milestone for Dash, bringing unprecedented flexibility to how you build and deploy your applications.

🚀 Multiple Backend Support

Dash is no longer tied to Flask. You can now run your Dash apps on FastAPI or Quart, or even bring your own backend implementation:

# FastAPI backendapp=Dash(__name__, backend="fastapi")
Quartbackend (async-native)
app=Dash(name, backend="quart")
OruseanexistingserverfromfastapiimportFastAPIserver=FastAPI()
app=Dash(name, server=server)

Install with pip install dash[fastapi] or pip install dash[quart].

⚡ Websocket Callbacks

Real-time, bidirectional communication is here. Websocket callbacks enable persistent connections for live updates without polling:

@callback(Output("live-output", "children"),Input("trigger", "n_clicks"),websocket=True,persistent=True)deflive_updates(n_clicks):
ws=ctx.websocketwhileTrue:
data=fetch_live_data()
ws.send(Output("live-output", "children", data))
time.sleep(1)

🔓 Relaxed Pattern Matching Rules

MATCH wildcards are now allowed in Input and State even when your Output has no wildcards, making dynamic UIs simpler to build:

@callback(Output("summary", "children"), # Fixed ID outputInput({"type": "item", "index": MATCH}, "value") # MATCH input - now allowed!)defupdate_summary(value):
returnf"Selected: {value}"</tr></table>

... (truncated)

Commits

• 887fd67 build artifacts for 4.2.0
• 805b3ce Merge pull request #3804 from plotly/master-4.2.0
• 3b483d1 build artifacts for 4.2.0
• ed2363d Merge branch 'dev' into master-4.2.0
• d0f78b6 Merge pull request #3803 from plotly/version-4.2.0
• 6c3fdab Version 4.2.0
• c41939b Merge pull request #3797 from plotly/fix/ws-connection-management
• 8c2329f add configuration for heartbeat and proper te\sts for reconnect
• e15ef05 Merge branch 'dev' into fix/ws-connection-management
• 715dae8 Merge pull request #3798 from plotly/fix/init-flask-run-command
• Additional commits viewable in compare view

[dependabot]

Superseded by #710.