Fix GroupBy variable multi property default and v2 conversion

- Default GroupBy variable multi to true in v1 to v2 conversions (frontend and backend)
- Add multi property to v2 to v1 conversion for GroupBy variables
- Add test case for GroupBy variable without explicit multi property
- Update test data and expected outputs

apps/dashboard/pkg/migration/conversion/testdata/input/v1beta1.variable-conversions.json

@@ -258,6 +258,23 @@
           "multi": true,
           "skipUrlSync": false
         },
+        {
+          "name": "groupby_var_no_multi",
+          "type": "groupby",
+          "label": "Group By Without Multi",
+          "description": "GroupBy variable without explicit multi - should default to true",
+          "datasource": {
+            "type": "prometheus",
+            "uid": "existing-ref-uid"
+          },
+          "current": {
+            "text": [],
+            "value": []
+          },
+          "options": [],
+          "hide": 0,
+          "skipUrlSync": false
+        },
         {
           "name": "switch_var",
           "type": "switch",
@@ -354,4 +371,4 @@
     },
     "links": []
   }
-} 
+} 

apps/dashboard/pkg/migration/conversion/testdata/output/v1beta1.variable-conversions.v0alpha1.json

@@ -277,6 +277,23 @@
           "skipUrlSync": false,
           "type": "groupby"
         },
+        {
+          "current": {
+            "text": [],
+            "value": []
+          },
+          "datasource": {
+            "type": "prometheus",
+            "uid": "existing-ref-uid"
+          },
+          "description": "GroupBy variable without explicit multi - should default to true",
+          "hide": 0,
+          "label": "Group By Without Multi",
+          "name": "groupby_var_no_multi",
+          "options": [],
+          "skipUrlSync": false,
+          "type": "groupby"
+        },
         {
           "current": {
             "selected": false,

apps/dashboard/pkg/migration/conversion/testdata/output/v1beta1.variable-conversions.v2alpha1.json

@@ -317,6 +317,26 @@
           "description": "Group results by field"
         }
       },
+      {
+        "kind": "GroupByVariable",
+        "spec": {
+          "name": "groupby_var_no_multi",
+          "datasource": {
+            "type": "prometheus",
+            "uid": "existing-ref-uid"
+          },
+          "current": {
+            "text": [],
+            "value": []
+          },
+          "options": [],
+          "multi": true,
+          "label": "Group By Without Multi",
+          "hide": "dontHide",
+          "skipUrlSync": false,
+          "description": "GroupBy variable without explicit multi - should default to true"
+        }
+      },
       {
         "kind": "SwitchVariable",
         "spec": {

apps/dashboard/pkg/migration/conversion/testdata/output/v1beta1.variable-conversions.v2beta1.json

@@ -318,6 +318,26 @@
           "description": "Group results by field"
         }
       },
+      {
+        "kind": "GroupByVariable",
+        "group": "prometheus",
+        "datasource": {
+          "name": "existing-ref-uid"
+        },
+        "spec": {
+          "name": "groupby_var_no_multi",
+          "current": {
+            "text": [],
+            "value": []
+          },
+          "options": [],
+          "multi": true,
+          "label": "Group By Without Multi",
+          "hide": "dontHide",
+          "skipUrlSync": false,
+          "description": "GroupBy variable without explicit multi - should default to true"
+        }
+      },
       {
         "kind": "SwitchVariable",
         "spec": {

apps/dashboard/pkg/migration/conversion/v1beta1_to_v2alpha1.go

@@ -1713,7 +1713,8 @@ func buildGroupByVariable(ctx context.Context, varMap map[string]interface{}, co
 			Hide:        commonProps.Hide,
 			SkipUrlSync: commonProps.SkipUrlSync,
 			Current:     buildVariableCurrent(varMap["current"]),
-			Multi:       getBoolField(varMap, "multi", false),
+			// GroupBy variables are multi-select by default in Grafana
+			Multi: getBoolField(varMap, "multi", true),
 		},
 	}
 

packages/grafana-schema/src/schema/dashboard/v2_examples.ts

@@ -419,7 +419,7 @@ export const handyTestingSchema: Spec = {
         description: 'A group by variable',
         hide: 'dontHide',
         label: 'Group By Variable',
-        multi: false,
+        multi: true,
         name: 'groupByVar',
         options: [
           {

public/app/features/dashboard/api/ResponseTransformers.test.ts

@@ -305,6 +305,7 @@ describe('ResponseTransformers', () => {
               description: 'groupby var description',
               skipUrlSync: false,
               hide: 0,
+              multi: true,
               datasource: {
                 type: 'prometheus',
                 uid: 'abc',
@@ -315,6 +316,21 @@ describe('ResponseTransformers', () => {
               ],
               current: { value: ['1'], text: ['1'] },
             },
+            // GroupBy variable without explicit multi - should default to true
+            {
+              type: 'groupby',
+              name: 'var8_no_multi',
+              label: 'groupby var without multi',
+              skipUrlSync: false,
+              hide: 0,
+              // Note: no multi property - GroupBy variables are multi by default
+              datasource: {
+                type: 'prometheus',
+                uid: 'abc',
+              },
+              options: [],
+              current: { value: [], text: [] },
+            },
             // Query variable with minimal props and without current
             {
               datasource: { type: 'prometheus', uid: 'abc' },
@@ -562,6 +578,17 @@ describe('ResponseTransformers', () => {
       validateVariablesV1ToV2(spec.variables[7], dashboardV1.templating?.list?.[7]);
       validateVariablesV1ToV2(spec.variables[8], dashboardV1.templating?.list?.[8]);
       validateVariablesV1ToV2(spec.variables[9], dashboardV1.templating?.list?.[9]);
+      validateVariablesV1ToV2(spec.variables[10], dashboardV1.templating?.list?.[10]);
+
+      // Verify GroupBy variable without explicit multi defaults to true
+      const groupByNoMulti = dashboardV1.templating?.list?.[8];
+      expect(groupByNoMulti?.type).toBe('groupby');
+      expect(groupByNoMulti?.multi).toBeUndefined();
+
+      const v2GroupByNoMulti = spec.variables[8];
+      expect(v2GroupByNoMulti.kind).toBe('GroupByVariable');
+      // @ts-expect-error
+      expect(v2GroupByNoMulti.spec.multi).toBe(true);
     });
   });
 
@@ -1224,6 +1251,8 @@ describe('ResponseTransformers', () => {
       expect(v2.datasource?.name).toEqual(v1.datasource?.uid);
       expect(v2.group).toEqual(v1.datasource?.type);
       expect(v2.spec.options).toEqual(v1.options);
+      // GroupBy variables default to multi: true when not specified
+      expect(v2.spec.multi).toEqual(v1.multi ?? true);
     }
 
     if (v2.kind === 'SwitchVariable') {

public/app/features/dashboard/api/ResponseTransformers.ts

@@ -812,7 +812,8 @@ function getVariables(vars: TypedVariableModel[]): DashboardV2Spec['variables']
               value: v.current.value,
               text: v.current.text,
             },
-            multi: v.multi,
+            // GroupBy variables are multi-select by default in Grafana
+            multi: v.multi ?? true,
           },
         };
 
@@ -1013,6 +1014,7 @@ function getVariablesV1(vars: DashboardV2Spec['variables']): VariableModel[] {
           },
           current: v.spec.current,
           options: v.spec.options,
+          multi: v.spec.multi,
         };
         variables.push(gv);
         break;