Loki: Fix missing parameters on Query Builder operations (#60677)

* add missing mandatory params

* improve naming

* change let to const

public/app/plugins/datasource/loki/querybuilder/operations.ts

@@ -2,7 +2,7 @@ import {
   createAggregationOperation,
   createAggregationOperationWithParam,
 } from '../../prometheus/querybuilder/shared/operationUtils';
-import { QueryBuilderOperationDef } from '../../prometheus/querybuilder/shared/types';
+import { QueryBuilderOperationDef, QueryBuilderOperationParamValue } from '../../prometheus/querybuilder/shared/types';
 
 import { binaryScalarOperations } from './binaryScalarOperations';
 import { UnwrapParamEditor } from './components/UnwrapParamEditor';
@@ -480,3 +480,16 @@ export function explainOperator(id: LokiOperationId | string): string {
   // Strip markdown links
   return explain.replace(/\[(.*)\]\(.*\)/g, '$1');
 }
+
+export function getDefinitionById(id: string): QueryBuilderOperationDef | undefined {
+  return definitions.find((x) => x.id === id);
+}
+
+export function checkParamsAreValid(def: QueryBuilderOperationDef, params: QueryBuilderOperationParamValue[]): boolean {
+  // For now we only check if the operation has all the required params.
+  if (params.length < def.params.filter((param) => !param.optional).length) {
+    return false;
+  }
+
+  return true;
+}

public/app/plugins/datasource/loki/querybuilder/parsing.test.ts

@@ -586,6 +586,81 @@ describe('buildVisualQueryFromString', () => {
       })
     );
   });
+
+  it('parses a regexp with empty string param', () => {
+    expect(buildVisualQueryFromString('{app="frontend"} | regexp "" ')).toEqual(
+      noErrors({
+        labels: [
+          {
+            op: '=',
+            value: 'frontend',
+            label: 'app',
+          },
+        ],
+        operations: [{ id: LokiOperationId.Regexp, params: [''] }],
+      })
+    );
+  });
+
+  it('parses a regexp with no param', () => {
+    expect(buildVisualQueryFromString('{app="frontend"} | regexp ')).toEqual(
+      noErrors({
+        labels: [
+          {
+            op: '=',
+            value: 'frontend',
+            label: 'app',
+          },
+        ],
+        operations: [{ id: LokiOperationId.Regexp, params: [''] }],
+      })
+    );
+  });
+
+  it('parses a pattern with empty string param', () => {
+    expect(buildVisualQueryFromString('{app="frontend"} | pattern "" ')).toEqual(
+      noErrors({
+        labels: [
+          {
+            op: '=',
+            value: 'frontend',
+            label: 'app',
+          },
+        ],
+        operations: [{ id: LokiOperationId.Pattern, params: [''] }],
+      })
+    );
+  });
+
+  it('parses a pattern with no param', () => {
+    expect(buildVisualQueryFromString('{app="frontend"} | pattern ')).toEqual(
+      noErrors({
+        labels: [
+          {
+            op: '=',
+            value: 'frontend',
+            label: 'app',
+          },
+        ],
+        operations: [{ id: LokiOperationId.Pattern, params: [''] }],
+      })
+    );
+  });
+
+  it('parses a json with no param', () => {
+    expect(buildVisualQueryFromString('{app="frontend"} | json ')).toEqual(
+      noErrors({
+        labels: [
+          {
+            op: '=',
+            value: 'frontend',
+            label: 'app',
+          },
+        ],
+        operations: [{ id: LokiOperationId.Json, params: [] }],
+      })
+    );
+  });
 });
 
 function noErrors(query: LokiVisualQuery) {

public/app/plugins/datasource/loki/querybuilder/parsing.ts

@@ -51,9 +51,14 @@ import {
   makeError,
   replaceVariables,
 } from '../../prometheus/querybuilder/shared/parsingUtils';
-import { QueryBuilderLabelFilter, QueryBuilderOperation } from '../../prometheus/querybuilder/shared/types';
+import {
+  QueryBuilderLabelFilter,
+  QueryBuilderOperation,
+  QueryBuilderOperationParamValue,
+} from '../../prometheus/querybuilder/shared/types';
 
 import { binaryScalarDefs } from './binaryScalarOperations';
+import { checkParamsAreValid, getDefinitionById } from './operations';
 import { LokiOperationId, LokiVisualQuery, LokiVisualQueryBinary } from './types';
 
 interface Context {
@@ -256,7 +261,12 @@ function getLabelParser(expr: string, node: SyntaxNode): QueryBuilderOperation {
   const parser = getString(expr, parserNode);
 
   const string = handleQuotes(getString(expr, node.getChild(String)));
-  const params = !!string ? [string] : [];
+  let params: QueryBuilderOperationParamValue[] = !!string ? [string] : [];
+  const opDef = getDefinitionById(parser);
+  if (opDef && !checkParamsAreValid(opDef, params)) {
+    params = opDef?.defaultParams || [];
+  }
+
   return {
     id: parser,
     params,