`AltairChart`¶

Render an Altair chart through the declarative visualization adapter.


Import	`from hedron_charts import AltairChart`
Distribution	`hedron-charts[altair]`
Backend activity	No
Normal render mode	`RenderMode.FRAGMENT`

Live demo¶

AltairChart outputAccessible static preview with a text conclusion.

The preview is a local docs simulation (not a running Hedron server). Interactive demos show a “Simulated HTMX” trace when applicable.

Install the optional provider before importing this component:

pip install "hedron-charts[altair]>=1.0.0,<2.0"

Basic use¶

from hedron_charts import AltairChart
import altair as alt
chart = alt.Chart({'values': [{'week': 'W1', 'deployments': 3}, {'week': 'W2', 'deployments': 5}]}).mark_bar().encode(x='week:N', y='deployments:Q')

component = AltairChart(chart, title='Deployments per week', description='Deployments peaked in week four.')

Compose under Page for full documents, or return from a fragment route for HTMX swaps.

How it works¶

The server compiles the chart specification under output and accessibility limits. Hedron owns the embedding contract instead of accepting arbitrary active markup.

The server emits bounded, non-executable JSON and accessible metadata. The interactive visual requires the corresponding vendored browser host/runtime; these adapters remain Experimental and fail closed when the runtime is unavailable.

Constructor and parameters¶

AltairChart(chart, *, title=None, description=None, alt=None, waiver=None)

Parameter	Type	Meaning
`chart`	`Altair Chart`	Declarative chart object.
`title / description / alt`	`str \| None`	Accessible metadata.
`waiver`	`str \| None`	Reviewed exception.

Composition and backend behavior¶

Keep AltairChart at the smallest semantic boundary. Fragment routes should return only the replaced region and preserve stable target IDs across success, validation, empty, loading, and error responses.

AltairChart renders data the server already prepared. Keep queries, authorization, and redaction on the route or data source — do not treat the component as a place for side effects.

Accessibility¶

Use encodings that remain distinguishable without color and provide a narrative or table alternative.

Security¶

Escaping and SafeUrl / TrustedHtml are framework concerns; authorization and data exposure remain application code. Redact secrets before rendering.

Common mistakes¶

Validate data volume and avoid specifications that fetch remote resources in the browser.
Do not copy docs-preview JavaScript into an application server.

Testing¶

from hedron import RenderMode, render

result = render(component, mode=RenderMode.FRAGMENT)
assert result.html
assert not result.diagnostics

Charts guide · Charts API · hedron-charts package

AltairChart¶