Metric

Type: metric • Category: visualization

Description

Store latest metric value

Parameters

Name	Type	Description	Required	Default
widgetId	string		no
metricExpr	string	Expr -> number or {value,label}	no
keepHistory	boolean		no	false
historyLimit	number		no	100

Help

Overview

The Metric Store Worker records the most recent value of a specified metric and makes it available for display in financial‑market widgets. It can also retain a configurable history of past values, enabling trend analysis or historical look‑ups.

Inputs

• widgetId (string) – Identifier of the widget that will consume the stored metric.
• metricExpr (string) – An expression that evaluates to either a numeric value or an object of the form {value, label}. The expression is executed each time the worker runs, and its result is stored.
• keepHistory (boolean, default = false) – When set to true, the worker retains previous metric values instead of only keeping the latest one.
• historyLimit (number, default = 100) – Maximum number of historic entries to keep when keepHistory is enabled. Older entries are discarded once this limit is reached.

Minimal Example Usage

Assume you want to track the latest price of the S&P 500 index and keep the last 50 values for charting:

• widgetId: sp500_chart
• metricExpr: fetchPrice('SPX') – returns a number representing the current index level.
• keepHistory: true
• historyLimit: 50

When the worker runs, it evaluates fetchPrice('SPX'), stores the resulting price under the widget sp500_chart, and appends the value to the history array (up to 50 entries). Subsequent runs overwrite the latest entry while preserving the historic series according to the configured limit.