fix(charts): normalize server_page_length from string to number #37517

VinayaKumar12 · 2026-01-28T08:57:12Z

fix(charts): normalize server_page_length from string to number

SUMMARY

Fixes a backend type comparison error ('<' not supported between instances of 'str' and 'int') that occurs when using custom server page length values in Table charts.

The SelectControl component with freeForm: true stores user-typed values as strings. When server_page_length is manually entered (e.g., "99"), it's saved as a string but the Python backend expects a number for comparison operations.

This PR adds type normalization in exploreReducer.js to convert server_page_length from string to number when the SET_FIELD_VALUE action is dispatched. The fix is targeted - only server_page_length is normalized, as other controls like row_limit don't exhibit this backend issue.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Before:

Screenshot showing the error: "Error loading chart datasources. Filters may not work correctly."

Backend console error: TypeError: '<' not supported between instances of 'str' and 'int'

After:

Screenshot showing the chart loads successfully with custom server page length value

TESTING INSTRUCTIONS

Create or open a Table chart
In the "Data" tab, expand "Server Pagination" section
Enable "Server Pagination" toggle
Manually type a custom value in "Server Page Length" field (e.g., 99)
Click "Update Chart"
Verify the chart loads successfully without backend errors
Run unit tests: cd superset-frontend && npm test -- exploreReducer.test.js

ADDITIONAL INFORMATION

Has associated issue:
Required feature flags:
Changes UI
Includes DB Migration (follow approval process in SIP-59)
- Migration is atomic, supports rollback & is backwards-compatible
- Confirm DB migration upgrade and downgrade tested
- Runtime estimates and downtime expectations provided
Introduces new feature or API
Removes existing feature or API

Fixes backend type comparison error where SelectControl with freeForm stores values as strings. Added normalization in exploreReducer for server_page_length control.

bito-code-review · 2026-01-28T08:57:23Z

Code Review Agent Run #7c4137

Actionable Suggestions - 0

Additional Suggestions - 2

superset-frontend/src/explore/reducers/exploreReducer.test.js - 1

Incomplete test coverage for edge case · Line 47-82

The added tests verify normalization for '100' but overlook '0', which exposes a flaw in the reducer where Number('0') || '0' incorrectly retains the string due to 0 being falsy. This could lead to unexpected string values in form_data.server_page_length.

Code suggestion

 @@ -82,1 +82,13 @@
-});
+});
+
+test('normalizes server_page_length from string "0" to number 0', () => {
+  const initialState = {
+    form_data: { viz_type: 'table' },
+    controls: {},
+  };
+
+  const action = setControlValue('server_page_length', '0');
+  const newState = exploreReducer(initialState, action);
+
+  expect(newState.form_data.server_page_length).toBe(0);
+  expect(typeof newState.form_data.server_page_length).toBe('number');
+});

superset-frontend/src/explore/reducers/exploreReducer.js - 1
- Comment spelling correction · Line 248-248
  
  The comment uses 'dependant', a less common variant; 'dependent' is preferred in American English and matches standard spelling.
  Code suggestion
  @@ -249,1 +249,1 @@ - // Re run validation for dependant controls + // Re run validation for dependent controls

Review Details

Files reviewed - 2 · Commit Range: 5060118..5060118
- superset-frontend/src/explore/reducers/exploreReducer.js
- superset-frontend/src/explore/reducers/exploreReducer.test.js
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netlify · 2026-01-28T09:01:28Z

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VinayaKumar12 · 2026-01-28T09:49:12Z

/review

bito-code-review · 2026-01-28T09:49:21Z

Code Review Agent Run #95cc7d

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Review Details

Files reviewed - 2 · Commit Range: 5060118..8911d2d
- superset-frontend/src/explore/reducers/exploreReducer.js
- superset-frontend/src/explore/reducers/exploreReducer.test.js
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bito-code-review · 2026-01-28T10:27:37Z

Code Review Agent Run #f27707

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Files reviewed - 2 · Commit Range: 5060118..8911d2d
- superset-frontend/src/explore/reducers/exploreReducer.js
- superset-frontend/src/explore/reducers/exploreReducer.test.js
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Pull request overview

This PR fixes a backend type comparison error that occurs when using custom server page length values in Table charts. The issue arises because the SelectControl component with freeForm: true stores user-typed values as strings, but the Python backend expects numeric values for comparison operations.

Changes:

Adds type normalization in the SET_FIELD_VALUE action handler to convert server_page_length from string to number
Implements targeted normalization that only affects server_page_length, preserving existing behavior for other controls
Adds comprehensive unit tests to verify the normalization behavior

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
superset-frontend/src/explore/reducers/exploreReducer.js	Adds normalization logic to convert `server_page_length` from string to number when the value is set, while preserving invalid strings for validation
superset-frontend/src/explore/reducers/exploreReducer.test.js	Adds test cases covering string-to-number conversion, numeric value preservation, non-normalization of other controls, and edge case handling for '0'

Copilot · 2026-01-28T18:27:47Z

superset-frontend/src/explore/reducers/exploreReducer.js

+      // Normalize server_page_length to number if it's a string
+      const normalizedValue =
+        controlName === 'server_page_length' && typeof value === 'string'


The normalization logic converts an empty string to the number 0, which may not be the intended behavior. Consider whether an empty string should be preserved for validation or converted to 0. If empty strings should remain for validation to catch, the logic should check for empty strings before conversion:

controlName === 'server_page_length' && typeof value === 'string' && value.trim() !== '' ? (isNaN(Number(value)) ? value : Number(value)) : value

This would align with the validateInteger function which checks v.trim().length > 0 before validation.

Suggested change

// Normalize server_page_length to number if it's a string

const normalizedValue =

controlName === 'server_page_length' && typeof value === 'string'

// Normalize server_page_length to number if it's a non-empty string

const normalizedValue =

controlName === 'server_page_length' &&

typeof value === 'string' &&

value.trim() !== ''

superset-frontend/src/explore/reducers/exploreReducer.test.js

superset-frontend/src/explore/reducers/exploreReducer.js

bito-code-review · 2026-01-29T11:01:57Z

Code Review Agent Run #fc04b0

Actionable Suggestions - 0

Review Details

Files reviewed - 2 · Commit Range: 8911d2d..a1648f4
- superset-frontend/src/explore/reducers/exploreReducer.js
- superset-frontend/src/explore/reducers/exploreReducer.test.js
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fix: normalize server_page_length from string to number

5060118

Fixes backend type comparison error where SelectControl with freeForm stores values as strings. Added normalization in exploreReducer for server_page_length control.

pull-request-size bot added the size/M label Jan 28, 2026

dosubot bot added the explore Namespace | Anything related to Explore label Jan 28, 2026

fixs for review comments

8911d2d

rusackas requested review from Copilot, justinpark and michael-s-molina January 28, 2026 18:22

Copilot started reviewing on behalf of rusackas January 28, 2026 18:23 View session

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review fixes: handled empty string scenario, added more unit test cases

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fix(charts): normalize server_page_length from string to number #37517

fix(charts): normalize server_page_length from string to number #37517

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VinayaKumar12 commented Jan 28, 2026

SUMMARY

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

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