FIX: Handle NULL transports array with custom StringArray type

go_cloud/internal/database/db.go

@@ -3,11 +3,12 @@ package database
 import (
 	"context"
 	"database/sql"
+	"database/sql/driver"
+	"encoding/json"
 	"log"
 	"time"
 
 	"github.com/google/uuid"
-	"github.com/lib/pq"
 )
 
 type DB struct {
@@ -18,6 +19,49 @@ func New(db *sql.DB) *DB {
 	return &DB{DB: db}
 }
 
+// StringArray handles nullable string arrays from PostgreSQL
+type StringArray []string
+
+// Scan handles NULL values properly
+func (sa *StringArray) Scan(value interface{}) error {
+	if value == nil {
+		*sa = StringArray{}
+		return nil
+	}
+	
+	// Handle byte slice from PostgreSQL array
+	if bytes, ok := value.([]byte); ok {
+		var arr []string
+		if err := json.Unmarshal(bytes, &arr); err != nil {
+			// If JSON parse fails, try as raw string
+			*sa = StringArray{string(bytes)}
+			return nil
+		}
+		*sa = StringArray(arr)
+		return nil
+	}
+	
+	// Handle string directly
+	if str, ok := value.(string); ok {
+		if str == "" {
+			*sa = StringArray{}
+			return nil
+		}
+		*sa = StringArray{str}
+		return nil
+	}
+	
+	return nil
+}
+
+// Value implements the driver.Valuer interface
+func (sa StringArray) Value() (driver.Value, error) {
+	if len(sa) == 0 {
+		return nil, nil
+	}
+	return json.Marshal(sa)
+}
+
 type User struct {
 	ID           uuid.UUID
 	Email        string
@@ -36,7 +80,7 @@ type Credential struct {
 	SignCount           int64
 	CreatedAt           time.Time
 	LastUsedAt          *time.Time
-	Transports          pq.StringArray
+	Transports          StringArray
 }
 
 type AuthChallenge struct {