Transformation: Add variable support for filter by value regex matcher (#90926)

* add support for template vars in filter by value transformation for regex matcher

* less code is more code

* add test to confirm interpolation works for regex

* suggestions input for regex editor

---------

Co-authored-by: Adela Almasan <adela.almasan@grafana.com>

packages/grafana-data/src/transformations/transformers/filterByValue.test.ts

@@ -305,6 +305,51 @@ describe('FilterByValue transformer', () => {
     });
   });
 
+  it('should interpolate dashboard variables for regex matcher', async () => {
+    mockTransformationsVariableSupport.mockReturnValue(true);
+
+    const regex: MatcherConfig<BasicValueMatcherOptions<string | number>> = {
+      id: ValueMatcherID.regex,
+      options: { value: '.*thiswillinterpolateto6' },
+    };
+
+    const cfg: DataTransformerConfig<FilterByValueTransformerOptions> = {
+      id: DataTransformerID.filterByValue,
+      options: {
+        type: FilterByValueType.include,
+        match: FilterByValueMatch.all,
+        filters: [
+          {
+            fieldName: 'numbers',
+            config: regex,
+          },
+        ],
+      },
+    };
+
+    const ctxmock = { interpolate: jest.fn(() => '6') };
+
+    await expect(transformDataFrame([cfg], [seriesAWithSingleField], ctxmock)).toEmitValuesWith((received) => {
+      const processed = received[0];
+
+      expect(processed.length).toEqual(1);
+      expect(processed[0].fields).toEqual([
+        {
+          name: 'time',
+          type: FieldType.time,
+          values: [6000],
+          state: {},
+        },
+        {
+          name: 'numbers',
+          type: FieldType.number,
+          values: [6],
+          state: {},
+        },
+      ]);
+    });
+  });
+
   it('should not interpolate dashboard variables when feature toggle is off', async () => {
     mockTransformationsVariableSupport.mockReturnValue(false);
 

packages/grafana-data/src/transformations/transformers/filterByValue.ts

@@ -77,9 +77,6 @@ export const filterByValueTransformer: DataTransformerInfo<FilterByValueTransfor
                 },
               },
             };
-          } else if (filter.config.id === ValueMatcherID.regex) {
-            // Due to colliding syntaxes, interpolating regex filters will cause issues.
-            return filter;
           } else if (filter.config.options.value) {
             let value = filter.config.options.value;
             if (typeof filter.config.options.value === 'string') {