Dashboard Migrations: V33 Replace string-based datasource by datasource ref (#106848)

---------
Co-authored-by: Stephanie Hingtgen <stephanie.hingtgen@grafana.com>

apps/dashboard/pkg/migration/schemaversion/datasource_utils.go

@@ -0,0 +1,110 @@
+package schemaversion
+
+// Shared utility functions for datasource migrations across different schema versions.
+// These functions handle the common logic for migrating datasource references from
+// string names/UIDs to structured reference objects with uid, type, and apiVersion.
+
+// GetDataSourceRef creates a datasource reference object with uid, type and optional apiVersion
+func GetDataSourceRef(ds *DataSourceInfo) map[string]interface{} {
+	if ds == nil {
+		return nil
+	}
+	ref := map[string]interface{}{
+		"uid":  ds.UID,
+		"type": ds.Type,
+	}
+	if ds.APIVersion != "" {
+		ref["apiVersion"] = ds.APIVersion
+	}
+	return ref
+}
+
+// GetDefaultDSInstanceSettings returns the default datasource if one exists
+func GetDefaultDSInstanceSettings(datasources []DataSourceInfo) *DataSourceInfo {
+	for _, ds := range datasources {
+		if ds.Default {
+			return &DataSourceInfo{
+				UID:        ds.UID,
+				Type:       ds.Type,
+				Name:       ds.Name,
+				APIVersion: ds.APIVersion,
+			}
+		}
+	}
+	return nil
+}
+
+// GetInstanceSettings looks up a datasource by name or uid reference
+func GetInstanceSettings(nameOrRef interface{}, datasources []DataSourceInfo) *DataSourceInfo {
+	if nameOrRef == nil || nameOrRef == "default" {
+		return GetDefaultDSInstanceSettings(datasources)
+	}
+
+	// Check if it's a reference object without UID - should return default
+	if ref, ok := nameOrRef.(map[string]interface{}); ok {
+		if _, hasUID := ref["uid"]; !hasUID {
+			return GetDefaultDSInstanceSettings(datasources)
+		}
+		// It's a reference object with UID, search for matching UID
+		for _, ds := range datasources {
+			if uid, hasUID := ref["uid"]; hasUID && uid == ds.UID {
+				return &DataSourceInfo{
+					UID:        ds.UID,
+					Type:       ds.Type,
+					Name:       ds.Name,
+					APIVersion: ds.APIVersion,
+				}
+			}
+		}
+		return GetDefaultDSInstanceSettings(datasources)
+	}
+
+	// Check if it's a string
+	str, ok := nameOrRef.(string)
+	if !ok {
+		return GetDefaultDSInstanceSettings(datasources)
+	}
+
+	// Search for matching name or UID
+	for _, ds := range datasources {
+		if str == ds.Name || str == ds.UID {
+			return &DataSourceInfo{
+				UID:        ds.UID,
+				Type:       ds.Type,
+				Name:       ds.Name,
+				APIVersion: ds.APIVersion,
+			}
+		}
+	}
+	return GetDefaultDSInstanceSettings(datasources)
+}
+
+// MigrateDatasourceNameToRef converts a datasource name/uid string to a reference object
+// Matches the frontend migrateDatasourceNameToRef function in DashboardMigrator.ts
+// Options:
+//   - returnDefaultAsNull: if true, returns nil for "default" datasources (used in V33)
+//   - returnDefaultAsNull: if false, returns reference for "default" datasources (used in V36)
+func MigrateDatasourceNameToRef(nameOrRef interface{}, options map[string]bool, datasources []DataSourceInfo) map[string]interface{} {
+	if options["returnDefaultAsNull"] && (nameOrRef == nil || nameOrRef == "default") {
+		return nil
+	}
+
+	if dsRef, ok := nameOrRef.(map[string]interface{}); ok {
+		if _, hasUID := dsRef["uid"]; hasUID {
+			return dsRef
+		}
+	}
+
+	ds := GetInstanceSettings(nameOrRef, datasources)
+	if ds != nil {
+		return GetDataSourceRef(ds)
+	}
+
+	if dsName, ok := nameOrRef.(string); ok && dsName != "" {
+		return map[string]interface{}{
+			"uid": dsName,
+		}
+	}
+
+	return nil
+}