EF下泛型分页方法，更新方法

Posted 2020-08-22 乐哈哈1

/// <summary>
        /// 获取分页的分页集合
        /// </summary>
        /// <typeparam name="S">实体类型</typeparam>
        /// <param name="filter">过滤，条件</param>
        /// <param name="pageIndex">当前页</param>
        /// <param name="pageSize">每页记录数</param>
        /// <param name="orderByExpression">排序</param>
        /// <param name="ascending">是否排序</param>
        /// <returns>返回分页的分页集合</returns>
        public PagedResult<T> GetFilteredPageResult<S, T>(Expression<Func<T, bool>> filter, int pageIndex, int pageSize, Expression<Func<T, S>> orderByExpression, bool ascending) where T : class
        {
            int count = this.DataContext.Set<T>().Where(filter).Count();
            return new PagedResult<T>(
                pageIndex,
                pageSize,
                count,
                this.GetFilteredElements<S,T>(filter, pageIndex, pageSize, orderByExpression, ascending));
        }

/// <summary>
        /// 获取有条件的分页对象集合
        /// </summary>
        /// <typeparam name="S">实体类型</typeparam>
        /// <param name="filter">条件过滤</param>
        /// <param name="pageIndex">当前页</param>
        /// <param name="pageSize">每页记录数</param>
        /// <param name="orderByExpression">排序，排序Func表达式</param>
        /// <param name="ascending">是否排序</param>
        /// <returns>返回有条件的分页对象集合</returns>
        public IEnumerable<T> GetFilteredElements<S, T>(Expression<Func<T, bool>> filter, int pageIndex, int pageSize, Expression<Func<T, S>> orderByExpression, bool ascending) where T : class
        {
            if (filter == (Expression<Func<T, bool>>)null)
            {
                throw new ArgumentNullException("filter", Messages.exception_FilterCannotBeNull);
            }

            if (pageIndex < 0)
            {
                throw new ArgumentException(Messages.exception_InvalidPageIndex);
            }

            if (pageSize <= 0)
            {
                throw new ArgumentException(Messages.exception_InvalidPageSize);
            }

            if (orderByExpression == (Expression<Func<T, S>>)null)
            {
                throw new ArgumentNullException("orderByExpression", Messages.exception_OrderByExpressionCannotBeNull);
            }

            return ascending
                ?
                    this.DataContext.Set<T>()
                    .Where(filter)
                    .OrderBy(orderByExpression)
                    .Skip((pageIndex - 1) * pageSize)
                    .Take(pageSize)
                    .ToList()
                :
                    this.DataContext.Set<T>()
                    .Where(filter)
                    .OrderByDescending(orderByExpression)
                    .Skip((pageIndex - 1) * pageSize)
                    .Take(pageSize)
                    .ToList();
        }

        /// <summary>
        /// 获取记录数
        /// </summary>
        /// <param name="filter">条件filter</param>
        /// <returns>返回记录数</returns>
        public int GetRecordCount<T>(Expression<Func<T, bool>> filter) where T : class
        {
            return this.DataContext.Set<T>().Where(filter).Count();
        }

public class PagedResult<TEntity>
    {
        /// <summary>
        /// 数据列表
        /// </summary>
        public IEnumerable<TEntity> List { get; private set; }

        /// <summary>
        /// 每页记录数
        /// </summary>
        public int PageSize { get; private set; }

        /// <summary>
        /// 页索引
        /// </summary>
        public int PageIndex { get; private set; }

        /// <summary>
        /// 总记录数
        /// </summary>
        public int RecordCount { get; private set; }

        /// <summary>
        /// 总页数
        /// </summary>
        public int TotalPages
        {
            get
            {
                int pages = 0;
                if (RecordCount > 0 && PageSize > 0)
                {


                    int temp = RecordCount % PageSize;
                    pages = RecordCount / PageSize;
                    if (temp > 0)
                    {
                        return pages + 1;
                    }
                }

                return pages;
            }
        }

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="pageIndex">页索引</param>
        /// <param name="pageSize">每页记录数</param>
        /// <param name="recordCount">总记录数</param>
        /// <param name="list">数据列表</param>
        public PagedResult(int pageIndex, int pageSize, int recordCount, IEnumerable<TEntity> list)
        {
            this.List = list;
            this.PageIndex = pageIndex;
            this.PageSize = pageSize;
            this.RecordCount = recordCount;
        }
    }

/// <summary>
/// 通过条件批量更新实体的部分值【异步更新】
/// </summary>
/// <param name="filterExpression">更新条件</param>
/// <param name="updateExpression">更新值</param>
public virtual void UpdateAsync<T>(Expression<Func<T, bool>> filterExpression, Expression<Func<T, T>> updateExpression) where T : class
{
DataContext.Set<T>().Where(filterExpression).UpdateAsync(updateExpression);
}