/// <summary>
/// 对实体集合进行批量操作。
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="instances"></param>
/// <param name="fnOperation"></param>
/// <returns>影响的实体数。</returns>
public async Task <int> BatchAsync(IEnumerable <TEntity> instances, Expression <Func <IRepository <TEntity>, TEntity, int> > fnOperation, CancellationToken cancellationToken = default)
{
return(await Queryable.BatchOperateAsync(instances.Cast <IEntity>(), fnOperation, cancellationToken));
}