gkhnelbstn opened a new issue, #42702:
URL: https://github.com/apache/superset/issues/42702
## Summary
On a stacked Timeseries Bar chart (`echarts_timeseries_bar`) with multiple
metrics/series and "Show Value" enabled (not "Only Total"), a series whose
value is exactly `0` for a given x-axis category still gets a visible value
label rendered, at the same pixel position as the label of the segment directly
below it (since a zero-height stacked segment starts and ends at the same
y-coordinate as the top of the previous segment). This produces a garbled,
overlapping text (e.g. two labels rendered on top of each other) wherever any
series is `0` for a category.
Related to, but distinct from, #42701 (which is about the "Only Total" sum
being wrong) — this one is about per-series labels overlapping in the default
(non-"Only Total") stacked label mode.
## Reproduction
1. Create an `echarts_timeseries_bar` chart with 2 metrics (e.g. `A`, `B`),
Stacked, "Show Value" on, "Only Total" off, "Percentage threshold" left at its
default (`0`).
2. Include at least one x-axis category where one metric is `0` and the
other is a large number, e.g. `{"category": "1-3g", "A": 32, "B": 0}`.
3. Run the chart.
4. **Bug**: the label for `B` (`0`) renders directly on top of the label for
`A` (`32`), since `B`'s stacked segment has zero height and starts exactly
where `A`'s segment ends. The two labels visually overlap into unreadable,
doubled text.
5. For categories where both metrics are non-zero, the labels render at
distinct heights and don't collide — confirming this is specific to the
zero-value case.
## Root cause
`plugins/plugin-chart-echarts/src/Timeseries/transformers.ts`, the
per-series `label.formatter`:
```ts
if (!onlyTotal) {
if (
numericValue >=
(thresholdValues[dataIndex] || Number.MIN_SAFE_INTEGER)
) {
return formatter(numericValue);
}
return '';
}
```
`thresholdValues[dataIndex]` comes from `extractDataTotalValues` in
`plugins/plugin-chart-echarts/src/utils/series.ts`:
```ts
thresholdValues.push(((percentageThreshold || 0) / 100) * values);
```
With the default `percentage_threshold: 0` (very common — it's the field's
default), `thresholdValues[dataIndex]` is `0` for every row, so the condition
becomes `numericValue >= 0`, which a value of exactly `0` always satisfies. The
label is shown for a segment with literally no visible height, landing exactly
on top of the neighboring segment's own label.
## Suggested fix
Require the value to be strictly positive (or otherwise non-zero) before
showing a per-series stacked label, regardless of the configured threshold:
```ts
if (!onlyTotal) {
if (
numericValue > 0 &&
numericValue >=
(thresholdValues[dataIndex] || Number.MIN_SAFE_INTEGER)
) {
return formatter(numericValue);
}
return '';
}
```
(A zero-height stacked segment has no meaningful position to attach a label
to regardless of threshold settings, so this seems safe as a default rather
than something that should require the user to configure a percentage
threshold.)
## Workaround
Set **Percentage threshold** to a small positive value (e.g. `1`). This
makes `thresholdValues[dataIndex]` a positive number for any category with a
non-zero total, so a `0`-valued series no longer clears the threshold and its
label is suppressed — eliminating the overlap without needing to touch every
category's data. Only works if you don't also want threshold-based hiding of
small-but-nonzero values, which is an inherent tradeoff of using this control
as the workaround.
## Environment
- Superset version: 6.1.0 (confirmed present at `refs/tags/6.1.0`)
- Chart type: `echarts_timeseries_bar` (Time-series Bar Chart), stacked,
"Show Value" on, "Only Total" off
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