fix: unable to add metadata in dataset (#17359)

### Summary

As title

internal/service/dataset/helpers.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"ragflow/internal/dao"
+	"ragflow/internal/entity"
 	pipelinepkg "ragflow/internal/ingestion/pipeline"
 	"ragflow/internal/service"
 
@@ -230,6 +231,26 @@ func datasetUpdateEmbeddingID(req service.UpdateDatasetRequest) (string, bool, e
 	return embdID, true, nil
 }
 
+func preserveDatasetParserConfigMetadata(next, existing entity.JSONMap, incoming map[string]interface{}) entity.JSONMap {
+	if next == nil {
+		next = entity.JSONMap{}
+	}
+	for _, key := range []string{"metadata", "built_in_metadata", "enable_metadata"} {
+		if incoming != nil {
+			if value, ok := incoming[key]; ok {
+				next[key] = value
+				continue
+			}
+		}
+		if existing != nil {
+			if value, ok := existing[key]; ok {
+				next[key] = value
+			}
+		}
+	}
+	return next
+}
+
 func normalizeDatasetUpdateExt(ext map[string]interface{}) map[string]interface{} {
 	if ext == nil {
 		return nil

internal/service/dataset/update.go

@@ -241,7 +241,8 @@ func (d *DatasetService) UpdateDataset(ctx context.Context, datasetID, tenantID
 					zap.String("parserID", effParserID), zap.Error(dslErr))
 			}
 			if dslJSON != nil {
-				updates["parser_config"] = pipelinepkg.BuildParserConfig(dslJSON, map[string]interface{}(req.ParserConfig))
+				parserConfig := pipelinepkg.BuildParserConfig(dslJSON, map[string]interface{}(req.ParserConfig))
+				updates["parser_config"] = preserveDatasetParserConfigMetadata(parserConfig, lockedKB.ParserConfig, req.ParserConfig)
 			}
 		}
 		if pagerankRequested {
@@ -260,7 +261,7 @@ func (d *DatasetService) UpdateDataset(ctx context.Context, datasetID, tenantID
 					common.Warn("failed to resolve component params defaults on parser_id switch",
 						zap.String("parserID", parserID), zap.Error(cpErr))
 				} else if resolved != nil {
-					updates["parser_config"] = resolved
+					updates["parser_config"] = preserveDatasetParserConfigMetadata(resolved, lockedKB.ParserConfig, req.ParserConfig)
 				}
 			}
 		}
@@ -280,7 +281,7 @@ func (d *DatasetService) UpdateDataset(ctx context.Context, datasetID, tenantID
 				common.Warn("failed to resolve component params defaults on pipeline change",
 					zap.String("parserID", cfgParserID), zap.Error(cpErr))
 			} else if cpDefaults != nil {
-				updates["parser_config"] = cpDefaults
+				updates["parser_config"] = preserveDatasetParserConfigMetadata(cpDefaults, lockedKB.ParserConfig, req.ParserConfig)
 			}
 		}
 		if len(updates) > 0 {

internal/service/dataset/update_test.go

@@ -18,6 +18,7 @@ package dataset
 
 import (
 	"encoding/json"
+	"reflect"
 	"strings"
 	"testing"
 
@@ -1043,6 +1044,101 @@ func TestUpdateDataset_AcceptsValidComponentParams_Builtin(t *testing.T) {
 	}
 }
 
+func TestUpdateDataset_PreservesIncomingMetadataWhenCleaningParserConfig(t *testing.T) {
+	db := setupDatasetUpdateTestDB(t)
+	pushServiceDB(t, db)
+	insertDatasetUpdateKB(t, "kb-1", "tenant-1", "Original")
+
+	incomingMetadata := []interface{}{map[string]interface{}{
+		"key":         "author",
+		"type":        "string",
+		"description": "Author",
+	}}
+	incomingBuiltInMetadata := []interface{}{map[string]interface{}{
+		"key":  "document_name",
+		"type": "string",
+	}}
+	parserConfig := map[string]interface{}{
+		"Parser:HipSignsRhyme": map[string]interface{}{
+			"pdf": map[string]interface{}{"parse_method": "deepdoc"},
+		},
+		"metadata":          incomingMetadata,
+		"built_in_metadata": incomingBuiltInMetadata,
+		"enable_metadata":   true,
+	}
+
+	_, code, err := testDatasetUpdateService(t).UpdateDataset(t.Context(), "kb-1", "tenant-1", service.UpdateDatasetRequest{
+		ParserConfig: parserConfig,
+	})
+	if err != nil || code != common.CodeSuccess {
+		t.Fatalf("UpdateDataset failed: code=%d err=%v", code, err)
+	}
+
+	persisted, err := dao.NewKnowledgebaseDAO().GetByID("kb-1")
+	if err != nil {
+		t.Fatalf("get updated kb: %v", err)
+	}
+	if !reflect.DeepEqual(persisted.ParserConfig["metadata"], incomingMetadata) {
+		t.Fatalf("metadata was not preserved: %#v", persisted.ParserConfig["metadata"])
+	}
+	if !reflect.DeepEqual(persisted.ParserConfig["built_in_metadata"], incomingBuiltInMetadata) {
+		t.Fatalf("built_in_metadata was not preserved: %#v", persisted.ParserConfig["built_in_metadata"])
+	}
+	if persisted.ParserConfig["enable_metadata"] != true {
+		t.Fatalf("enable_metadata was not preserved: %#v", persisted.ParserConfig["enable_metadata"])
+	}
+	if _, ok := persisted.ParserConfig["Parser:HipSignsRhyme"].(map[string]interface{}); !ok {
+		t.Fatalf("component parser_config missing: %#v", persisted.ParserConfig)
+	}
+}
+
+func TestUpdateDataset_PreservesExistingMetadataWhenParserConfigOmitsIt(t *testing.T) {
+	db := setupDatasetUpdateTestDB(t)
+	pushServiceDB(t, db)
+	insertDatasetUpdateKB(t, "kb-1", "tenant-1", "Original")
+
+	existingMetadata := []interface{}{map[string]interface{}{
+		"key":  "category",
+		"type": "string",
+	}}
+	existingBuiltInMetadata := []interface{}{map[string]interface{}{
+		"key":  "document_name",
+		"type": "string",
+	}}
+	if err := dao.DB.Model(&entity.Knowledgebase{}).Where("id = ?", "kb-1").Update("parser_config", entity.JSONMap{
+		"metadata":          existingMetadata,
+		"built_in_metadata": existingBuiltInMetadata,
+		"enable_metadata":   true,
+	}).Error; err != nil {
+		t.Fatalf("seed parser_config: %v", err)
+	}
+
+	_, code, err := testDatasetUpdateService(t).UpdateDataset(t.Context(), "kb-1", "tenant-1", service.UpdateDatasetRequest{
+		ParserConfig: map[string]interface{}{
+			"Parser:HipSignsRhyme": map[string]interface{}{
+				"pdf": map[string]interface{}{"parse_method": "deepdoc"},
+			},
+		},
+	})
+	if err != nil || code != common.CodeSuccess {
+		t.Fatalf("UpdateDataset failed: code=%d err=%v", code, err)
+	}
+
+	persisted, err := dao.NewKnowledgebaseDAO().GetByID("kb-1")
+	if err != nil {
+		t.Fatalf("get updated kb: %v", err)
+	}
+	if !reflect.DeepEqual(persisted.ParserConfig["metadata"], existingMetadata) {
+		t.Fatalf("existing metadata was not preserved: %#v", persisted.ParserConfig["metadata"])
+	}
+	if !reflect.DeepEqual(persisted.ParserConfig["built_in_metadata"], existingBuiltInMetadata) {
+		t.Fatalf("existing built_in_metadata was not preserved: %#v", persisted.ParserConfig["built_in_metadata"])
+	}
+	if persisted.ParserConfig["enable_metadata"] != true {
+		t.Fatalf("existing enable_metadata was not preserved: %#v", persisted.ParserConfig["enable_metadata"])
+	}
+}
+
 func TestUpdateDataset_StripsCanvasUnknownParam(t *testing.T) {
 	db := setupDatasetUpdateTestDB(t)
 	pushServiceDB(t, db)