fix: resolve NULL email scan in comments and merge patch for owners/labels

Fix #214: Comment queries scanned nullable user fields (email, uuid)
into plain Go strings, which fails when the value is NULL. Added a
CommentModel with sql.NullString fields (matching the existing
DiscussionModel pattern) to safely handle nullable columns.

Fix #173: UpsertPatchAsset deep-merged the Data map but completely
replaced Owners (slice) and Labels (map). Now all three fields merge
consistently — existing labels are preserved with new keys added,
and existing owners are kept with new owners appended (deduplicated
by email or uuid).

Author: ravisuhag

core/asset/asset_test.go

@@ -310,10 +310,12 @@ func TestAssetPatch(t *testing.T) {
 				Name:        "new-name",
 				URL:         "https://sample-url.com",
 				Labels: map[string]string{
+					"foo":  "bar",
 					"bar":  "foo",
 					"bar2": "foo2",
 				},
 				Owners: []user.User{
+					{Email: "old@example.com"},
 					{Email: "new@example.com"},
 					{Email: "new2@example.com"},
 				},
@@ -359,10 +361,12 @@ func TestAssetPatch(t *testing.T) {
 				Name:        "new-name",
 				URL:         "https://sample-url.com",
 				Labels: map[string]string{
+					"foo":  "bar",
 					"bar":  "foo",
 					"bar2": "foo2",
 				},
 				Owners: []user.User{
+					{Email: "old@example.com"},
 					{Email: "new@example.com"},
 					{Email: "new2@example.com"},
 				},
@@ -397,6 +401,12 @@ func TestAssetPatch(t *testing.T) {
 				Service:     "firehose",
 				Description: "new-description",
 				Name:        "new-name",
+				Labels: map[string]string{
+					"foo": "bar",
+				},
+				Owners: []user.User{
+					{Email: "old@example.com"},
+				},
 			},
 		},
 		{

core/asset/patch.go

@@ -1,8 +1,8 @@
 package asset
 
 import (
-	"github.com/raystack/compass/core/user"
 	"github.com/peterbourgon/mergemap"
+	"github.com/raystack/compass/core/user"
 )
 
 // patch appends asset with data from map. It mutates the asset itself.
@@ -16,18 +16,80 @@ func patchAsset(a *Asset, patchData map[string]interface{}) {
 
 	labels, exists := patchData["labels"]
 	if exists {
-		a.Labels = buildLabels(labels)
+		a.Labels = mergeLabels(a.Labels, buildLabels(labels))
 	}
 	owners, exists := patchData["owners"]
 	if exists {
-		a.Owners = buildOwners(owners)
+		a.Owners = mergeOwners(a.Owners, buildOwners(owners))
 	}
 	data, exists := patchData["data"]
 	if exists {
 		patchAssetData(a, data)
 	}
 }
 
+// mergeLabels merges new labels into existing ones. New values override existing keys.
+func mergeLabels(existing, patch map[string]string) map[string]string {
+	if existing == nil {
+		return patch
+	}
+	if patch == nil {
+		return existing
+	}
+	for k, v := range patch {
+		existing[k] = v
+	}
+	return existing
+}
+
+// mergeOwners merges new owners into existing ones, deduplicating by email or uuid.
+func mergeOwners(existing, patch []user.User) []user.User {
+	if existing == nil {
+		return patch
+	}
+	if patch == nil {
+		return existing
+	}
+
+	seen := make(map[string]int) // key -> index in result
+	result := make([]user.User, len(existing))
+	copy(result, existing)
+
+	for i, o := range result {
+		if key := ownerKey(o); key != "" {
+			seen[key] = i
+		}
+	}
+
+	for _, o := range patch {
+		key := ownerKey(o)
+		if key == "" {
+			result = append(result, o)
+			continue
+		}
+		if idx, exists := seen[key]; exists {
+			// update existing owner in-place
+			result[idx] = o
+		} else {
+			seen[key] = len(result)
+			result = append(result, o)
+		}
+	}
+
+	return result
+}
+
+// ownerKey returns a deduplication key for an owner (email preferred, then uuid).
+func ownerKey(o user.User) string {
+	if o.Email != "" {
+		return "email:" + o.Email
+	}
+	if o.UUID != "" {
+		return "uuid:" + o.UUID
+	}
+	return ""
+}
+
 // buildLabels builds labels from interface{}
 func buildLabels(data interface{}) (labels map[string]string) {
 	switch d := data.(type) {

store/postgres/comment_model.go

@@ -0,0 +1,29 @@
+package postgres
+
+import (
+	"time"
+
+	"github.com/raystack/compass/core/discussion"
+)
+
+type CommentModel struct {
+	ID           string    `db:"id"`
+	DiscussionID string    `db:"discussion_id"`
+	Body         string    `db:"body"`
+	Owner        UserModel `db:"owner"`
+	UpdatedBy    UserModel `db:"updated_by"`
+	CreatedAt    time.Time `db:"created_at"`
+	UpdatedAt    time.Time `db:"updated_at"`
+}
+
+func (cm CommentModel) toComment() discussion.Comment {
+	return discussion.Comment{
+		ID:           cm.ID,
+		DiscussionID: cm.DiscussionID,
+		Body:         cm.Body,
+		Owner:        cm.Owner.toUser(),
+		UpdatedBy:    cm.UpdatedBy.toUser(),
+		CreatedAt:    cm.CreatedAt,
+		UpdatedAt:    cm.UpdatedAt,
+	}
+}

store/postgres/discussion_comment_repository.go

@@ -60,12 +60,16 @@ func (r *DiscussionRepository) GetAllComments(ctx context.Context, did string, f
 		return nil, fmt.Errorf("error building query: %w", err)
 	}
 
-	cmts := []discussion.Comment{}
-	err = r.client.SelectContext(ctx, &cmts, query, args...)
+	var models []CommentModel
+	err = r.client.SelectContext(ctx, &models, query, args...)
 	if err != nil {
 		return nil, fmt.Errorf("error getting list of comments: %w", err)
 	}
 
+	cmts := make([]discussion.Comment, 0, len(models))
+	for _, m := range models {
+		cmts = append(cmts, m.toComment())
+	}
 	return cmts, nil
 }
 
@@ -82,16 +86,16 @@ func (r *DiscussionRepository) GetComment(ctx context.Context, cid string, did s
 		return discussion.Comment{}, fmt.Errorf("error building query: %w", err)
 	}
 
-	cmt := discussion.Comment{}
-	err = r.client.GetContext(ctx, &cmt, query, args...)
+	var model CommentModel
+	err = r.client.GetContext(ctx, &model, query, args...)
 	if errors.Is(err, sql.ErrNoRows) {
 		return discussion.Comment{}, discussion.NotFoundError{CommentID: cid, DiscussionID: did}
 	}
 	if err != nil {
-		return discussion.Comment{}, fmt.Errorf("error getting list of comments: %w", err)
+		return discussion.Comment{}, fmt.Errorf("error getting comment: %w", err)
 	}
 
-	return cmt, nil
+	return model.toComment(), nil
 }
 
 // Update updates a comment