Line chart skips intermediate categories when x‑axis is string (but data exists) · apache/superset#35853

2025-10-27T07:27:06.000Z

### Bug description Environment Superset version: v6.x Upgrade path: imported charts from v4 → v6 Database: ClickHouse Chart type: Line chart Description When using a string dimension for the x‑axis (e.g. LEFT(toString(day_id), 6) ), the line chart connects non‑adjacent categories even though intermediate categories exist in the dataset. With a numeric dimension ( toInt32(LEFT(...)) ), the chart renders correctly and includes all intermediate points. Steps to Reproduce Run the following query in SQL Lab: -- INT version SELECT toInt32(LEFT(toString(day_id), 6)) AS month_id, sum(value) AS total_value FROM ( SELECT toInt32(formatDateTime(d, '%Y%m%d')) AS day_id, toDayOfYear(d) AS value FROM ( SELECT addDays(toDate('2024-01-01'), number) AS d FROM numbers(366) -- leap year ) WHERE d < toDate('2024-05-15') OR d > toDate('2024-08-10') ) GROUP BY month_id ORDER BY month_id; -- STRING version SELECT LEFT(toString(day_id), 6) AS month_id, sum(value) AS total_value FROM ( SELECT toInt32(formatDateTime(d, '%Y%m%d')) AS day_id, toDayOfYear(d) AS value FROM ( SELECT addDays(toDate('2024-01-01'), number) AS d FROM numbers(366) ) WHERE d < toDate('2024-05-15') OR d > toDate('2024-08-10') ) GROUP BY month_id ORDER BY month_id; Both queries return the following aggregated dataset: month_id | SUM(value) -- | -- 202401 | 496 202402 | 1334 202403 | 2356 202404 | 3195 202405 | 1799 202408 | 4914 202409 | 7785 202410 | 8990 202411 | 9615 202412 | 10881 Create two line charts: Chart A: x‑axis = month_id (INT) Chart B: x‑axis = month_id (STRING) Expected Behavior Both charts should render a line through all categories present in the dataset , including 202408 . Actual Behavior INT chart : renders correctly → line goes 202405 → 202408 → 202409 . STRING chart : skips 202408 and draws a line directly from 202405 → 202409 , even though 202408 exists in the dataset. Notes This behavior changed between Superset v4 and v6. In v4, both INT and STRING behaved the same. In v6, categorical (string) axes appear stricter, but this results in valid categories being skipped in line charts. Query to reproduce Virtual Dataset: ``` SELECT toInt32(formatDateTime(d, '%Y%m%d')) AS day_id, toDayOfYear(d) AS value FROM ( SELECT addDays(toDate('2024-01-01'), number) AS d FROM numbers(366) -- 2024 is a leap year ) WHERE d toDate('2024-08-10') ORDER BY day_id ``` ### Screenshots/recordings _No response_ ### Superset version master / latest-dev ### Python version 3.11 ### Node version 18 or greater ### Browser Chrome ### Additional context _No response_ ### Checklist - [x] I have searched Superset docs and Slack and didn't find a solution to my problem. - [x] I have searched the GitHub issue tracker and didn't find a similar bug report. - [x] I have checked Superset's logs for errors and if I found a relevant Python stacktrace, I included it here as text in the "additional context" section.

(10 comments) (0 reactions) (1 assignee)TypeScript (72,837 stars) (17,291 forks)batch import

good first issue

Description

Bug description

month_id	SUM(value)
202401	496
202402	1334
202403	2356
202404	3195
202405	1799
202408	4914
202409	7785
202410	8990
202411	9615
202412	10881

Query to reproduce Virtual Dataset:

SELECT
    toInt32(formatDateTime(d, '%Y%m%d')) AS day_id,
    toDayOfYear(d) AS value
FROM (
    SELECT addDays(toDate('2024-01-01'), number) AS d
    FROM numbers(366)  -- 2024 is a leap year
) 
WHERE d < toDate('2024-05-15')
   OR d > toDate('2024-08-10')
ORDER BY day_id

Screenshots/recordings

No response

Superset version

master / latest-dev

Python version

3.11

Node version

18 or greater

Browser

Chrome

Additional context

No response

Checklist

I have searched Superset docs and Slack and didn't find a solution to my problem.
I have searched the GitHub issue tracker and didn't find a similar bug report.
I have checked Superset's logs for errors and if I found a relevant Python stacktrace, I included it here as text in the "additional context" section.

Contributor guide

Tech stack: typescriptpythonreact
Domain: frontenddata
Issue type: bug
Difficulty: 3
Estimated time: 1-3 hours
Activity status: blocked
Clarity: clear
Prerequisites: ReactTypeScriptApache Superset basics
Newbie friendliness: 40
Research direction: Investigate the line chart's x axis handling for string categories. The bug likely resides in the visualization plugin code, possibly in the sorting or category mapping logic. Check the comments for any proposed fix or related code paths. Focus on how the chart determines which categories to display and why intermediate categories are skipped when the axis type is string.