Data Apps

Data Apps

Data apps are custom dashboard tiles built with HTML, CSS, and JavaScript. Use them when you need a layout or interaction that CorralData's native chart types can't deliver — interactive tables, multi-panel views, custom gauges, or any bespoke visualization.

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Creating a data app

The easiest way is to ask AskCorral. Describe what you want in plain English — the data, the layout, any filters — and AskCorral will write the HTML/CSS/JS and wire up the SQL queries automatically.

You can also create data apps through the Claude or ChatGPT MCP connector if you have widget.edit access.

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How data apps differ from standard widgets

Native CorralData widgets (line charts, fuel gauges, tables) are configured through SQL and display settings. Data apps give you full control, with a few important constraints:

	Native widget	Data app
SQL	Inline in widget settings	Named queries, called via JavaScript
Board filter tokens (${param})	Substituted into SQL automatically	Not substituted — filtering happens in JavaScript
Styling	CorralData theme applied automatically	You write all CSS; use CSS variables for theme compatibility
Grid sizing	Per-type defaults	Requires grid_width: "4-full" and grid_height: "auto"

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The most important thing to know

Board filter tokens do not work in data app SQL.

Tokens like ${brand}, ${location}, and ${date_start} are substituted into SQL for standard widgets — but not for data apps. In a data app, ${brand} arrives at the database as the literal text ${brand} and returns no results.

All filtering in a data app happens in JavaScript, after the data is loaded. When you ask AskCorral or Claude to build a data app with filters, this is handled automatically — just describe the filter behavior you want.

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Running SQL queries in a data app

SQL is registered as named queries and called from JavaScript at runtime:

const result = await corral.runNamedQuery('revenue_by_location');
// result = { columns: ['location', 'revenue'], rows: [['Main St', '12450.00'], ...] }

// Rows are tuples — convert to objects before use
const data = result.rows.map(r =>
  Object.fromEntries(result.columns.map((c, i) => [c, r[i]]))
);

All query result values are strings, including numbers. Use Number(val) before doing any arithmetic.

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Reading board filters in JavaScript

// Get current filter state
const bf = corral.getBoardFilters();
// bf.filterParams is an ARRAY: [{ name: 'location', value: 'main_street' }, ...]

// Find a filter value by name
const location = bf.filterParams.find(p => p.name === 'location')?.value;

// Re-render when filters change
corral.on('filtersChanged', () => {
  // re-read filters and update the display
});

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Common mistakes

Mistake	What happens	Fix
${param} token in SQL	Query returns no results	Remove the token; apply the filter in JavaScript instead
Using raw string values in arithmetic	Silent NaN or broken math	Coerce with Number(val) before calculations
Fixed height on the iframe body	Layout gets clipped	Use grid_height: "auto" — never set height: 100% on the page body
External JavaScript library from a CDN	Script blocked by the sandbox	Only CorralData's built-in chart toolkit is available

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Getting help

Ask AskCorral, Claude, or ChatGPT to build, fix, or modify a data app in plain English. For help debugging an existing one, share what's not working and the AI will diagnose and fix it.