fix: preserve period ids for program-level time dimensions in event PTs

src/components/PivotTable/PivotTableValueCell.js

@@ -24,6 +24,13 @@ export const PivotTableValueCell = ({
         column,
     })
 
+    // engine.get returns undefined when the requested cell falls outside the
+    // current row/column maps (e.g. a degenerate matrix with no rows or
+    // columns). Render an empty cell rather than dereferencing undefined.
+    if (!cellContent) {
+        return <PivotTableEmptyCell ref={cellRef} classes={['value']} />
+    }
+
     const isClickable =
         onToggleContextualMenu &&
         cellContent.cellType === CELL_TYPE_VALUE &&
@@ -37,7 +44,7 @@ export const PivotTableValueCell = ({
         onToggleContextualMenu(cellRef.current, { ouId: cellContent.ouId })
     }
 
-    if (!cellContent || cellContent.empty) {
+    if (cellContent.empty) {
         return (
             <PivotTableEmptyCell
                 onClick={isClickable ? onClick : undefined}

src/modules/pivotTable/__tests__/clipPartitionedAxis.spec.js

@@ -0,0 +1,37 @@
+import { clipPartitionedAxis } from '../clipPartitionedAxis.js'
+
+describe('clipPartitionedAxis', () => {
+    it('renders no indices for an empty axis (no partitions)', () => {
+        // A degenerate matrix (e.g. a dimension with no members) yields an
+        // empty axis map and therefore no partitions. This must render nothing
+        // rather than a phantom index 0 that isn't in the map (which made
+        // engine.get return undefined and PivotTableValueCell throw).
+        const result = clipPartitionedAxis({
+            partitionSize: 400,
+            partitions: [],
+            axisMap: [],
+            widthMap: [],
+            viewportWidth: 1000,
+            viewportPosition: 0,
+            totalWidth: 0,
+        })
+
+        expect(result.indices).toEqual([])
+        expect(result.pre).toBe(0)
+        expect(result.post).toBe(0)
+    })
+
+    it('still falls back to index 0 when scrolled past the last partition of a non-empty axis', () => {
+        const result = clipPartitionedAxis({
+            partitionSize: 400,
+            partitions: [0],
+            axisMap: [0],
+            widthMap: [{ pre: 0, size: 100 }],
+            viewportWidth: 500,
+            viewportPosition: 100000, // far beyond the only partition
+            totalWidth: 100,
+        })
+
+        expect(result.indices).toEqual([0])
+    })
+})

src/modules/pivotTable/clipPartitionedAxis.js

@@ -9,6 +9,17 @@ export const clipPartitionedAxis = ({
 }) => {
     const partition = Math.floor(viewportPosition / partitionSize)
 
+    // Empty axis (no rows/columns to render, e.g. a degenerate matrix where a
+    // dimension has no members). Render nothing instead of falling back to a
+    // phantom index 0 that isn't present in the axis map.
+    if (partitions.length === 0) {
+        return {
+            indices: [],
+            pre: 0,
+            post: 0,
+        }
+    }
+
     if (partitions[partition] === undefined) {
         return {
             indices: [0],

src/modules/response/event/__tests__/timeDimensions.spec.js

@@ -0,0 +1,39 @@
+import { transformResponse } from '../response.js'
+
+const months = ['202505', '202506', '202507']
+
+// Minimal enrollment/aggregate-style response with NO data rows.
+// The server still returns the full relative-period buckets in
+// metaData.dimensions for the period dimensions.
+const makeEmptyResponse = () => ({
+    headers: [
+        { name: 'value', valueType: 'NUMBER', meta: false },
+        { name: 'enrollmentdate', valueType: 'TEXT', meta: true },
+        { name: 'A03MvHHogjR.eventdate', valueType: 'DATE', meta: true },
+    ],
+    metaData: {
+        items: months.reduce((o, m) => ({ ...o, [m]: { name: m } }), {}),
+        dimensions: {
+            enrollmentdate: [...months],
+            'A03MvHHogjR.eventdate': [...months],
+        },
+    },
+    rows: [],
+})
+
+describe('transformResponse - time dimension members', () => {
+    it('preserves the bare program-level time dimension members when there are no rows', () => {
+        const { metaData } = transformResponse(makeEmptyResponse())
+
+        // Regression: applyDefaultHandler used to re-derive enrollmentdate's
+        // members from the (empty) rows and overwrite the server buckets with
+        // [], collapsing the pivot table (dataWidth -> 0 -> cellType crash).
+        expect(metaData.dimensions.enrollmentdate).toEqual(months)
+    })
+
+    it('preserves the stage-prefixed time dimension members when there are no rows', () => {
+        const { metaData } = transformResponse(makeEmptyResponse())
+
+        expect(metaData.dimensions['A03MvHHogjR.eventdate']).toEqual(months)
+    })
+})

src/modules/response/event/response.js

@@ -96,10 +96,21 @@ const EXCLUDED_HEADER_SUFFIXES = [
     '.ou',
 ]
 
+// Time/org-unit dimensions must keep the dimension members provided by the
+// server (e.g. all the period buckets of a relative period like LAST_12_MONTHS)
+// instead of having them re-derived from the data rows by applyDefaultHandler.
+// EXCLUDED_HEADER_SUFFIXES already covers the program-stage-prefixed forms
+// (e.g. "<stageId>.eventdate"); their bare, program-level counterparts
+// (e.g. "enrollmentdate") must be excluded too, otherwise a response with no
+// rows would re-derive an empty members list and collapse the pivot table.
+const isExcludedHeaderName = (name) =>
+    EXCLUDED_HEADER_NAMES.has(name) ||
+    EXCLUDED_HEADER_SUFFIXES.some(
+        (suffix) => name.endsWith(suffix) || name === suffix.slice(1)
+    )
+
 const isIncludedHeader = (header) =>
-    Boolean(header.meta) &&
-    !EXCLUDED_HEADER_NAMES.has(header.name) &&
-    !EXCLUDED_HEADER_SUFFIXES.some((suffix) => header.name.endsWith(suffix))
+    Boolean(header.meta) && !isExcludedHeaderName(header.name)
 
 export const transformResponse = (response, { hideNaData = false } = {}) => {
     // Do not modify the original response