apache/superset · error

Please call with an object. Example: `stringify myObj`

Error message

Please call with an object. Example: `stringify myObj`

What it means

A Handlebars helper registered by the Handlebars (markdown-templated) chart plugin. The stringify helper throws when it is invoked in a template without a usable argument (the second positional parameter is undefined), telling the template author to call it as {{stringify myObj}} to pretty-print an object.

Source

Thrown at superset-frontend/plugins/plugin-chart-handlebars/src/components/Handlebars/HandlebarsViewer.tsx:90

        htmlSanitization={htmlSanitization}
        htmlSchemaOverrides={htmlSchemaOverrides}
      />
    );
  }
  return <p>{t('Loading...')}</p>;
};

//  usage: {{ dateFormat my_date format="MMMM YYYY" }}
Handlebars.registerHelper('dateFormat', function (context, block) {
  const f = block.hash.format || 'YYYY-MM-DD';
  return dayjs(context).format(f);
});

// usage: {{  }}
Handlebars.registerHelper('stringify', (obj: any, obj2: any) => {
  // calling without an argument
  if (obj2 === undefined)
    throw new Error('Please call with an object. Example: `stringify myObj`');
  return isPlainObject(obj) ? JSON.stringify(obj) : String(obj);
});

Handlebars.registerHelper(
  'formatNumber',
  function (number: any, locale = 'en-US') {
    if (typeof number !== 'number') {
      return number;
    }
    return number.toLocaleString(locale);
  },
);

// usage: {{parseJson jsonString}}
Handlebars.registerHelper('parseJson', (jsonString: string) => {
  try {
    return JSON.parse(jsonString);
  } catch (error) {

View on GitHub (pinned to f4587218dd)

Solutions

1. Fix the template: call {{stringify myObj}} with an actual object field present in the query result.
2. Guard in the template: {{#if myObj}}{{stringify myObj}}{{/if}}.
3. Verify the column names in the template match the dataset columns returned by the chart query.
4. Render the chart with sample rows in Explore to confirm the field exists before publishing.

Example fix

{{! before }}
{{stringify}}

{{! after }}
{{#if row.payload}}
  {{stringify row.payload}}
{{/if}}

{{! inside the Handlebars template }}
{{#if myObj}}
  {{stringify myObj}}
{{/if}}

{{! custom guard helper or inline check }}
{{#if (isPlainObject myObj)}}
  {{stringify myObj}}
{{else}}
  <span class="muted">n/a</span>
{{/if}}

try {
  const html = Handlebars.compile(templateString)(data);
} catch (e) {
  if (e instanceof Error && e.message.includes('stringify')) {
    setTemplateError(t('Template calls stringify without an object; check field names'));
    return;
  }
  throw e;
}

When it happens

Trigger: A Handlebars template used by the chart contains {{stringify}} with no argument, or passes undefined (e.g. {{stringify missingField}} where the field is absent from the row).

Common situations: Templates authored against sample data where the field existed, then pointed at data missing that column; typos in field names inside the template; templates copied from just-handlebars-factories examples.

Related errors

• Invalid JSON string: ${String(error)}
• When using 'Group By' you are limited to use a single metric
• Group by param is required
• Unknown deck.gl layer type: ${vizType}
• Error in jinja expression in fetch values predicate: %(msg)s

AI-assisted analysis of apache/superset@f4587218dd (2026-08-14). Data as JSON: /api/errors/237948eceb59952b. Report an issue: GitHub.