reflex-nivo

Every chart of nivo — the React data-visualization library built on d3 — as a Reflex custom component.

• 51 components from 28 nivo packages, SVG, Canvas and HTML renderers (nivo 0.99.0).
• snake_case props generated from nivo's TypeScript declarations, with types and nivo docs links.
• Events land in Python: on_click, on_mouse_enter, on_node_click, on_arc_click… receive the datum as a JSON-safe dict (cycles, DOM nodes and React events are stripped in the browser).
• Follows Reflex's light/dark mode out of the box.
• Helpers for axes, legends, scales, color configs, patterns/gradients, markers and annotations, plus nivo.tooltip("<b>{id}</b>: {formattedValue}") templates and a nivo.js(...) escape hatch.

pip install reflex-nivo

Quick start

import reflex as rx
import reflex_nivo as nivo


class State(rx.State):
    rows: list[dict] = [
        {"country": "AD", "burger": 120, "fries": 80},
        {"country": "AE", "burger": 95, "fries": 130},
    ]
    selected: str = ""

    @rx.event
    def on_bar_click(self, datum: dict):
        self.selected = f"{datum['indexValue']} · {datum['id']} = {datum['value']}"


def index():
    return rx.vstack(
        nivo.bar(
            data=State.rows,
            keys=["burger", "fries"],
            index_by="country",
            group_mode="grouped",
            colors=nivo.scheme("nivo"),
            margin=nivo.margin(top=20, right=110, bottom=50, left=60),
            axis_bottom=nivo.axis(legend="country", legend_position="middle", legend_offset=36),
            legends=[nivo.legend(data_from="keys", anchor="bottom-right", translate_x=100)],
            tooltip=nivo.tooltip("<b>{indexValue}</b> · {id}: {formattedValue}"),
            on_click=State.on_bar_click,
            height="400px",
        ),
        rx.text(State.selected),
    )


app = rx.App()
app.add_page(index)

Components

Each factory wraps nivo's Responsive* export. Classes use the nivo name (nivo.Bar, nivo.HeatMapCanvas…).

The data shape and every prop are documented on nivo.rocks (each class docstring links to its page). Convert prop names to snake_case: indexBy → index_by, enableGridX → enable_grid_x.

Renamed props

Plain YYYY-MM-DD values for from_date/to_date are sent as local midnight, so calendars do not shift one day (and one year) back west of Greenwich.

Sizing

nivo's responsive charts fill their parent, so every factory returns the chart inside a <div>. width (default "100%"), height (default "400px") and any other CSS prop, class_name, id or style go to that container. Anything that is neither a nivo prop nor CSS raises a TypeError with a suggestion, so typos like enable_gridx do not fail silently.

nivo.pie(data=State.pie, height="320px", max_width="600px", margin_x="auto")

(margin itself is nivo's chart margin: use nivo.margin(top=.., right=.., bottom=.., left=..).)

Events

All nivo callbacks are exposed as event triggers. The handler receives nivo's first callback argument (datum, point, slice, node, cell, serie, link, feature, dimensions, active id…), serialized in the browser: functions, DOM nodes and React events are dropped, repeated/cyclic objects are replaced by their id, and depth is bounded.

class State(rx.State):
    @rx.event
    def drill_down(self, node: dict):
        if node["data"].get("children"):
            self.sunburst = node["data"]  # the raw datum travels with the event


nivo.sunburst(data=State.sunburst, id_by="name", value="loc", on_click=State.drill_down)

Only the callbacks a chart actually declares carry a datum, and they differ per chart: @nivo/bar exposes on_click, on_mouse_enter and on_mouse_leave, while @nivo/stream exposes none of them. Any other on_* is attached to the wrapping <div> as a plain DOM event, so it fires for the whole chart area but receives no datum (write the handler without arguments). An on_* that is neither raises a TypeError listing the chart's nivo callbacks.

on_mouse_move fires very often; on the charts that expose it, prefer click/enter/leave or throttle it: on_mouse_move=State.hover.throttle(100).

Hiding a prop

Passing None sends JavaScript null, which turns the feature off instead of falling back to nivo's default — that is how you hide an axis:

nivo.bar(data=State.rows, axis_bottom=None, axis_left=None)  # no axes
nivo.pie(data=State.pie, theme=None)  # nivo's own theme instead of the Reflex one

Helpers

nivo.margin(top=20, right=20, bottom=40, left=50)
nivo.axis(legend="price", legend_position="middle", legend_offset=-40, tick_rotation=-45, format=" >-$.2f")
nivo.legend(
    anchor="bottom-right", direction="column", translate_x=100, effects=[nivo.hover_effect(item_opacity=1)]
)
nivo.scale("time", format="%Y-%m-%d", precision="day")
nivo.scheme("category10")  # {"scheme": "category10"}
nivo.inherit("color", ("darker", 1.6))  # inherited color
nivo.from_theme("background")  # color from theme
nivo.marker("y", 100, legend="target")
nivo.annotation({"id": "fries"}, type_="circle", note="max", note_x=40, note_y=-30)
nivo.pattern_dots_def("dots", background="inherit", color="#38bcb2")
nivo.pattern_lines_def("lines", rotation=-45) / nivo.pattern_squares_def(...) / nivo.linear_gradient_def(...)
nivo.fill_rule("dots", {"id": "fries"})
nivo.props(any_snake_case="option")  # generic camelCase dict builder

Constants: nivo.COLOR_SCHEMES (categorical/diverging/sequential), nivo.CURVES, nivo.MOTION_CONFIGS.

Functions: templates, tooltips and raw JS

nivo accepts functions for labels, formatters, accessors, tooltips and custom layers.

# Formatter/label from a {path} template, evaluated in the browser:
label = nivo.template("{id}: {formattedValue}")

# Tooltip component from a template. It may use attribute-less <b>, <strong>, <i>, <em>, <u>,
# <s>, <small>, <code>, <span>, <div>, <p> and <br>; anything else, and every interpolated
# value, is rendered as text, so template and values are safe to build from a state Var.
tooltip = nivo.tooltip("<b>{datum.label}</b><br/>{datum.formattedValue}", style={"min_width": "120px"})

# Anything else: a raw JavaScript expression (never build it from user input).
value_format = nivo.js("v => `${v.toLocaleString()} €`")
node_size = nivo.js("n => n.size")

Most formatters also accept d3-format / d3-time-format strings directly (value_format=".2s", axis(format="%b %d")).

Themes

Charts use nivo.themes.auto() unless you pass theme=: a light/dark pair built on the Radix gray scale that switches with rx.color_mode. Customize or pin it:

theme = nivo.themes.auto({"grid": {"line": {"strokeDasharray": "4 4"}}})  # both modes
theme = nivo.themes.auto(light={"text": {"fill": "#333"}}, dark={"text": {"fill": "#eee"}})
theme = nivo.themes.DARK  # fixed
theme = State.computed_theme  # any nivo theme dict
theme = {}  # nivo's own default

Demo

nivo_demo/ is a 10-page app that uses all 51 components with live state controls, an event inspector, drill-down/zoom interactions, geo projections, canvas variants with thousands of marks and customization examples.

uv venv && uv pip install -e . && cd nivo_demo && uv pip install -r requirements.txt
uv run reflex run   # http://localhost:3000

If a tab from another Reflex app is still open on the same ports, its frontend reconnects to this backend and the console reports no dispatch function for substate(s): close or reload that tab, or give one of the apps its own frontend_port/backend_port.

World country shapes in the demo come from the nivo website dataset (Natural Earth).

Regenerating the wrappers

The chart modules in custom_components/reflex_nivo/charts/ are generated from nivo's typings:

# in a scratch directory
npm i typescript@5 @types/react@19 react@19 react-dom@19 @nivo/{bar,line,pie,...}@0.99.0
node /path/to/reflex-nivo/scripts/extract_nivo_props.cjs bar boxplot bullet bump calendar chord \
  circle-packing funnel heatmap icicle line marimekko network pie polar-bar radar radial-bar sankey \
  scatterplot stream sunburst swarmplot tree treemap voronoi waffle > /path/to/reflex-nivo/scripts/nivo_props.json
# back in the repo (geo and parallel-coordinates ship no usable typings: see scripts/nivo_manual_props.json)
python scripts/generate_components.py

Bump NIVO_VERSION in custom_components/reflex_nivo/constants.py together with the extraction.

Development

uv pip install -e ".[dev]"
uv run pytest
uv run reflex component build     # generates .pyi stubs, then sdist + wheel in dist/

License

MIT © Ernesto Crespo. nivo is MIT © Raphaël Benitte.