SSE: Add functions that determine NodeType by UID and construct a data source struct from NodeType (#70106)

* add NodeTypeFromDatasourceUID and DataSourceModelFromNodeType()
* deprecate expr.DataSourceModel
* replace usages of IsDataSource to NodeTypeFromDatasourceUID 
* replace usages of DataSourceModel to DataSourceModelFromNodeType()

pkg/services/ngalert/eval/eval.go

@@ -269,13 +269,14 @@ func getExprRequest(ctx EvaluationContext, data []models.AlertQuery, dsCacheServ
 
 		ds, ok := datasources[q.DatasourceUID]
 		if !ok {
-			if expr.IsDataSource(q.DatasourceUID) {
-				ds = expr.DataSourceModel()
-			} else {
+			switch nodeType := expr.NodeTypeFromDatasourceUID(q.DatasourceUID); nodeType {
+			case expr.TypeCMDNode:
+				ds, err = expr.DataSourceModelFromNodeType(nodeType)
+			case expr.TypeDatasourceNode:
 				ds, err = dsCacheService.GetDatasourceByUID(ctx.Ctx, q.DatasourceUID, ctx.User, false /*skipCache*/)
-				if err != nil {
-					return nil, fmt.Errorf("failed to build query '%s': %w", q.RefID, err)
-				}
+			}
+			if err != nil {
+				return nil, fmt.Errorf("failed to build query '%s': %w", q.RefID, err)
 			}
 			datasources[q.DatasourceUID] = ds
 		}
@@ -621,7 +622,7 @@ func (e *evaluatorImpl) Validate(ctx EvaluationContext, condition models.Conditi
 		return err
 	}
 	for _, query := range req.Queries {
-		if query.DataSource == nil || expr.IsDataSource(query.DataSource.UID) {
+		if query.DataSource == nil || expr.NodeTypeFromDatasourceUID(query.DataSource.UID) != expr.TypeDatasourceNode {
 			continue
 		}
 		p, found := e.pluginsStore.Plugin(ctx.Ctx, query.DataSource.Type)

pkg/services/ngalert/models/alert_query.go

@@ -113,7 +113,7 @@ func (aq *AlertQuery) setModelProps() error {
 
 // IsExpression returns true if the alert query is an expression.
 func (aq *AlertQuery) IsExpression() (bool, error) {
-	return expr.IsDataSource(aq.DatasourceUID), nil
+	return expr.NodeTypeFromDatasourceUID(aq.DatasourceUID) == expr.TypeCMDNode, nil
 }
 
 // setMaxDatapoints sets the model maxDataPoints if it's missing or invalid

pkg/services/query/query.go

@@ -269,7 +269,7 @@ func (s *ServiceImpl) parseMetricRequest(ctx context.Context, user *user.SignedI
 		}
 
 		datasourcesByUid[ds.UID] = ds
-		if expr.IsDataSource(ds.UID) {
+		if expr.NodeTypeFromDatasourceUID(ds.UID) != expr.TypeDatasourceNode {
 			req.hasExpression = true
 		} else {
 			req.dsTypes[ds.Type] = true
@@ -321,8 +321,8 @@ func (s *ServiceImpl) getDataSourceFromQuery(ctx context.Context, user *user.Sig
 		return ds, nil
 	}
 
-	if expr.IsDataSource(uid) {
-		return expr.DataSourceModel(), nil
+	if kind := expr.NodeTypeFromDatasourceUID(uid); kind != expr.TypeDatasourceNode {
+		return expr.DataSourceModelFromNodeType(kind)
 	}
 
 	if uid == grafanads.DatasourceUID {