Variables & Conditional Visibility

Variables are the in-report writable state. They answer the question "which row did the user just click?" — the viewer mutates them; expressions read them. Crucially, nothing inside the viewer mutates parameters. Drills, cell clicks, chart clicks all write to variables. Parameters only change via the parameter panel’s Apply button.

A variable has a scope: global variables live on the report and are writable from anywhere; component variables are declared on a specific component and are only writable from within that component’s subtree. Outside the subtree, reads fall through to the global bucket with the same name (or null).

1 · Global variable + drill-through → conditional visibility

The classic pattern. Clicking a row writes the row into a global variable; a downstream component reads it and toggles visibility.

Orders — click a row to reveal the detail panel

The table’s Drill-through Variable is set to `selectedOrder`. Clicking a row writes the full row object into the variable; the detail panel below checks `!IsEmpty(Variables.selectedOrder)` in styles.visible to appear once a selection exists. Parameters never change from this interaction.

Order	Region	Product	Revenue
ORD-1000	East	Water Bottle	$689
ORD-1001	West	T-Shirt	$70
ORD-1002	East	T-Shirt	$60
ORD-1003	West	T-Shirt	$357
ORD-1004	West	Wireless Buds	$4,942
ORD-1005	West	Yoga Mat	$470
ORD-1006	East	Sneakers	$261
ORD-1007	South	Sneakers	$738
ORD-1008	West	Throw Pillow	$888
ORD-1009	North	Smart Watch	$1,392
ORD-1010	East	Jacket	$440
ORD-1011	West	Smart Watch	$5,073
ORD-1012	North	Water Bottle	$492
ORD-1013	South	Jeans	$949
ORD-1014	South	Sneakers	$413
ORD-1015	East	Jeans	$540
ORD-1016	West	T-Shirt	$584
ORD-1017	West	Desk Lamp	$812
ORD-1018	East	Water Bottle	$588
ORD-1019	South	Wireless Buds	$5,895
ORD-1020	East	T-Shirt	$936
ORD-1021	North	Throw Pillow	$296
ORD-1022	East	Throw Pillow	$779
ORD-1023	East	Yoga Mat	$432
ORD-1024	East	Candle Set	$71
ORD-1025	East	Wireless Buds	$3,080
ORD-1026	South	Running Shoes	$315
ORD-1027	East	Candle Set	$728
ORD-1028	West	Dumbbells	$689
ORD-1029	South	Jeans	$915
ORD-1030	East	Wireless Buds	$3,078
ORD-1031	North	Laptop Pro	$3,485
ORD-1032	South	Candle Set	$585
ORD-1033	South	Throw Pillow	$859
ORD-1034	South	USB Hub	$3,302
ORD-1035	South	Water Bottle	$477
ORD-1036	West	Smart Watch	$1,350
ORD-1037	East	Water Bottle	$451
ORD-1038	West	Dumbbells	$204
ORD-1039	North	Rug 5x8	$1,180
ORD-1040	East	Jeans	$1,188
ORD-1041	East	Desk Lamp	$697
ORD-1042	South	Jeans	$72
ORD-1043	West	Candle Set	$500
ORD-1044	North	Candle Set	$779
ORD-1045	East	Candle Set	$1,180
ORD-1046	North	Yoga Mat	$656
ORD-1047	West	T-Shirt	$186
ORD-1048	East	Jacket	$1,134
ORD-1049	South	Water Bottle	$760
ORD-1050	East	Sneakers	$303
ORD-1051	East	Candle Set	$122
ORD-1052	North	Desk Lamp	$228
ORD-1053	East	Water Bottle	$402
ORD-1054	South	Dumbbells	$1,060
ORD-1055	West	Yoga Mat	$526
ORD-1056	West	Yoga Mat	$256
ORD-1057	South	Jeans	$1,008
ORD-1058	West	Throw Pillow	$341
ORD-1059	South	Smart Watch	$3,780
ORD-1060	South	Jeans	$122
ORD-1061	West	T-Shirt	$1,292
ORD-1062	West	Laptop Pro	$3,729
ORD-1063	East	Running Shoes	$392
ORD-1064	South	Sneakers	$852
ORD-1065	East	Yoga Mat	$37
ORD-1066	East	Jacket	$960
ORD-1067	North	T-Shirt	$684
ORD-1068	North	USB Hub	$2,056
ORD-1069	South	Running Shoes	$714
ORD-1070	West	Rug 5x8	$1,037
ORD-1071	North	Water Bottle	$600
ORD-1072	East	Wireless Buds	$1,275
ORD-1073	West	Running Shoes	$216
ORD-1074	East	Desk Lamp	$489
ORD-1075	West	Smart Watch	$2,718
ORD-1076	North	Rug 5x8	$688
ORD-1077	South	Running Shoes	$90
ORD-1078	South	Sneakers	$1,501
ORD-1079	South	T-Shirt	$336

2 · Component-scoped variables

Two tables, same variable name, independent buckets. Click a row in one — the other is unaffected.

Component-scoped variables

Each table below declares its own `localSelection` variable (scope = component). Drills in one table do NOT leak into the other — the scope walker only writes to the nearest enclosing declaration that knows the name.

North / Order	Product	Revenue
ORD-1009	Smart Watch	$1,392
ORD-1012	Water Bottle	$492
ORD-1021	Throw Pillow	$296
ORD-1031	Laptop Pro	$3,485
ORD-1039	Rug 5x8	$1,180
ORD-1044	Candle Set	$779
ORD-1046	Yoga Mat	$656
ORD-1052	Desk Lamp	$228
ORD-1067	T-Shirt	$684
ORD-1068	USB Hub	$2,056
ORD-1071	Water Bottle	$600
ORD-1076	Rug 5x8	$688

South / Order	Product	Revenue
ORD-1007	Sneakers	$738
ORD-1013	Jeans	$949
ORD-1014	Sneakers	$413
ORD-1019	Wireless Buds	$5,895
ORD-1026	Running Shoes	$315
ORD-1029	Jeans	$915
ORD-1032	Candle Set	$585
ORD-1033	Throw Pillow	$859
ORD-1034	USB Hub	$3,302
ORD-1035	Water Bottle	$477
ORD-1042	Jeans	$72
ORD-1049	Water Bottle	$760
ORD-1054	Dumbbells	$1,060
ORD-1057	Jeans	$1,008
ORD-1059	Smart Watch	$3,780
ORD-1060	Jeans	$122
ORD-1064	Sneakers	$852
ORD-1069	Running Shoes	$714
ORD-1077	Running Shoes	$90
ORD-1078	Sneakers	$1,501
ORD-1079	T-Shirt	$336

3 · Set-variable cell action (buttons / pills)

Cell items can set a variable to an arbitrary expression value. Use this for view-mode toggles or anything that is not a row selection.

Buttons that write to variables

The three rows in the first table are backed by a tiny `modes` datasource. Each row's Label column uses a `set-variable` cell-item that writes the row's key into `viewMode`. The main orders table below has a footer expression that reads `Variables.viewMode` via Switch() and shows the matching aggregate.

Click a mode to switch the footer aggregate

Current mode: revenue

Order	Region	Product	Units	Revenue	Cost
ORD-1000	East	Water Bottle	13	$689	$344
ORD-1001	West	T-Shirt	1	$70	$32
ORD-1002	East	T-Shirt	1	$60	$33
ORD-1003	West	T-Shirt	5	$357	$213
ORD-1004	West	Wireless Buds	14	$4,942	$2,311
ORD-1005	West	Yoga Mat	10	$470	$219
ORD-1006	East	Sneakers	3	$261	$165
ORD-1007	South	Sneakers	9	$738	$479
ORD-1008	West	Throw Pillow	16	$888	$546
ORD-1009	North	Smart Watch	4	$1,392	$684
ORD-1010	East	Jacket	8	$440	$254
ORD-1011	West	Smart Watch	15	$5,073	$2,624
ORD-1012	North	Water Bottle	12	$492	$264
ORD-1013	South	Jeans	13	$949	$472
ORD-1014	South	Sneakers	7	$413	$189
ORD-1015	East	Jeans	9	$540	$300
ORD-1016	West	T-Shirt	8	$584	$320
ORD-1017	West	Desk Lamp	14	$812	$498
ORD-1018	East	Water Bottle	14	$588	$338
ORD-1019	South	Wireless Buds	15	$5,895	$3,202
ORD-1020	East	T-Shirt	12	$936	$568
ORD-1021	North	Throw Pillow	7	$296	$149
ORD-1022	East	Throw Pillow	19	$779	$418
ORD-1023	East	Yoga Mat	12	$432	$259
ORD-1024	East	Candle Set	2	$71	$41
ORD-1025	East	Wireless Buds	11	$3,080	$1,972
ORD-1026	South	Running Shoes	7	$315	$176
ORD-1027	East	Candle Set	13	$728	$384
ORD-1028	West	Dumbbells	13	$689	$331
ORD-1029	South	Jeans	15	$915	$577
ORD-1030	East	Wireless Buds	9	$3,078	$1,704
ORD-1031	North	Laptop Pro	14	$3,485	$2,056
ORD-1032	South	Candle Set	13	$585	$296
ORD-1033	South	Throw Pillow	14	$859	$392
ORD-1034	South	USB Hub	13	$3,302	$2,013
ORD-1035	South	Water Bottle	9	$477	$262
ORD-1036	West	Smart Watch	5	$1,350	$770
ORD-1037	East	Water Bottle	12	$451	$267
ORD-1038	West	Dumbbells	4	$204	$132
ORD-1039	North	Rug 5x8	20	$1,180	$579
ORD-1040	East	Jeans	18	$1,188	$594
ORD-1041	East	Desk Lamp	17	$697	$390
ORD-1042	South	Jeans	1	$72	$43
ORD-1043	West	Candle Set	10	$500	$300
ORD-1044	North	Candle Set	19	$779	$426
ORD-1045	East	Candle Set	20	$1,180	$722
ORD-1046	North	Yoga Mat	16	$656	$355
ORD-1047	West	T-Shirt	3	$186	$98
ORD-1048	East	Jacket	18	$1,134	$714
ORD-1049	South	Water Bottle	20	$760	$353
ORD-1050	East	Sneakers	4	$303	$179
ORD-1051	East	Candle Set	2	$122	$68
ORD-1052	North	Desk Lamp	4	$228	$105
ORD-1053	East	Water Bottle	12	$402	$240
ORD-1054	South	Dumbbells	20	$1,060	$550
ORD-1055	West	Yoga Mat	11	$526	$300
ORD-1056	West	Yoga Mat	8	$256	$147
ORD-1057	South	Jeans	14	$1,008	$572
ORD-1058	West	Throw Pillow	9	$341	$180
ORD-1059	South	Smart Watch	14	$3,780	$1,864
ORD-1060	South	Jeans	2	$122	$76
ORD-1061	West	T-Shirt	19	$1,292	$623
ORD-1062	West	Laptop Pro	11	$3,729	$2,070
ORD-1063	East	Running Shoes	8	$392	$211
ORD-1064	South	Sneakers	12	$852	$508
ORD-1065	East	Yoga Mat	1	$37	$22
ORD-1066	East	Jacket	15	$960	$483
ORD-1067	North	T-Shirt	12	$684	$428
ORD-1068	North	USB Hub	8	$2,056	$1,123
ORD-1069	South	Running Shoes	14	$714	$443
ORD-1070	West	Rug 5x8	17	$1,037	$514
ORD-1071	North	Water Bottle	14	$600	$297
ORD-1072	East	Wireless Buds	5	$1,275	$584
ORD-1073	West	Running Shoes	6	$216	$121
ORD-1074	East	Desk Lamp	9	$489	$230
ORD-1075	West	Smart Watch	9	$2,718	$1,617
ORD-1076	North	Rug 5x8	16	$688	$399
ORD-1077	South	Running Shoes	2	$90	$45
ORD-1078	South	Sneakers	19	$1,501	$765
ORD-1079	South	T-Shirt	6	$336	$157
Total (revenue)			$83,831

Notes

Drill writes the whole row. If you only need one field, use a cell-item drill action with drillValueExpr, or just read the path (Variables.selectedOrder.id) downstream.
Scope resolution is bottom-up. A cell action writes to the nearest enclosing component that declares the variable name. If no component declares it, it falls back to the global bucket.
Default values are expressions. defaultValueExpression: "=Today()" seeds the variable on first render; explicit writes override it thereafter.
Host visibility. onDrillThrough(variableName, value) still fires as a pure notification — use it if the host app needs to react (analytics, navigation) in addition to the in-report variable write.