*/ use HasFactory; protected $fillable = [ 'type', // 'electricity', 'water', 'gas', etc. 'billing_period_start', 'billing_period_end', 'due_date', 'amount', 'usage_amount', // kWh, m3, etc. 'unit', // 度, 立方米 'status', // 'pending', 'paid', 'overdue' 'paid_at', 'payment_method', 'notes', 'receipt_image_path', ]; protected $casts = [ 'billing_period_start' => 'date', 'billing_period_end' => 'date', 'due_date' => 'date', 'paid_at' => 'datetime', 'amount' => 'decimal:2', 'usage_amount' => 'decimal:2', ]; }