Candle Chart

Type: candle_chart • Category: visualization

Description

Store OHLC candlestick data for chart widget

Parameters

Name	Type	Description	Required	Default
widgetId	string		no
rowsExpr	string	Expr -> list[dict] (each dict: ts, o, h, l, c)	no
columns	array	Optional list of columns (ts, o, h, l, c)	no
open	string		no
close	string		no
high	string		no
low	string		no
volume	string		no
timestamp	string		no
limit	number		no	500

Help

Overview

This worker stores Open‑High‑Low‑Close (OHLC) candlestick data for a chart widget. It receives a list of price‑time records, optionally filters the columns, and saves the processed data under the specified widget identifier.

Inputs

• widgetId (string) – Unique identifier of the chart widget that will receive the data.
• rowsExpr (string) – An expression that evaluates to a list of dictionaries, each containing the fields ts, o, h, l, c. These represent timestamp, open, high, low, and close values respectively.
• columns (array, optional) – List of column names to retain from each row. Acceptable values are any subset of ts, o, h, l, c. If omitted, all columns are stored.
• open (string) – Name of the field that holds the opening price (default: o).
• close (string) – Name of the field that holds the closing price (default: c).
• high (string) – Name of the field that holds the highest price (default: h).
• low (string) – Name of the field that holds the lowest price (default: l).
• volume (string) – Name of the field that holds the traded volume, if present.
• timestamp (string) – Name of the field that holds the timestamp (default: ts).
• limit (number, default = 500) – Maximum number of rows to store. Excess rows are truncated.

Minimal Example Usage

widgetId: "chart-123"
rowsExpr: "fetchCandles('AAPL', '1h', 1000)"   # returns a list of dicts with ts, o, h, l, c
columns: ["ts", "o", "h", "l", "c"]
open: "o"
close: "c"
high: "h"
low: "l"
timestamp: "ts"
limit: 300

In this example the worker retrieves 1‑hour OHLC candles for the ticker AAPL, keeps only the standard five columns, and stores up to 300 rows under the widget identified by "chart-123".