Explore: Add transformations to correlation data links (#61799)

* bring in source from database

* bring in transformations from database

* add regex transformations to scopevar

* Consolidate types, add better example, cleanup

* Add var only if match

* Change ScopedVar to not require text, do not leak transformation-made variables between links

* Add mappings and start implementing logfmt

* Add mappings and start implementing logfmt

* Remove mappings, turn off global regex

* Add example yaml and omit transformations if empty

* Fix the yaml

* Add logfmt transformation

* Cleanup transformations and yaml

* add transformation field to FE types and use it, safeStringify logfmt values

* Add tests, only safe stringify if non-string, fix bug with safe stringify where it would return empty string with false value

* Add test for transformation field

* Do not add null transformations object

* Break out transformation logic, add tests to backend code

* Fix lint errors I understand 😅

* Fix the backend lint error

* Remove unnecessary code and mark new Transformations object as internal

* Add support for named capture groups

* Remove type assertion

* Remove variable name from transformation

* Add test for overriding regexes

* Add back variable name field, but change to mapValue

* fix go api test

* Change transformation types to enum, add better provisioning checks for bad type name and format

* Check for expression with regex transformations

packages/grafana-data/src/types/ScopedVars.ts

@@ -1,5 +1,5 @@
 export interface ScopedVar<T = any> {
-  text: any;
+  text?: any;
   value: T;
   [key: string]: any;
 }

packages/grafana-data/src/types/dataLink.ts

@@ -40,12 +40,27 @@ export interface DataLink<T extends DataQuery = any> {
   internal?: InternalDataLink<T>;
 }
 
+/** @internal */
+export enum SupportedTransformationTypes {
+  Regex = 'regex',
+  Logfmt = 'logfmt',
+}
+
+/** @internal */
+export interface DataLinkTransformationConfig {
+  type: SupportedTransformationTypes;
+  field?: string;
+  expression?: string;
+  mapValue?: string;
+}
+
 /** @internal */
 export interface InternalDataLink<T extends DataQuery = any> {
   query: T;
   datasourceUid: string;
   datasourceName: string; // used as a title if `DataLink.title` is empty
   panelsState?: ExplorePanelsState;
+  transformations?: DataLinkTransformationConfig[];
 }
 
 export type LinkTarget = '_blank' | '_self' | undefined;