C# EntityFrameworkCore 分页

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已于 2024-03-13 00:14:42 修改

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分类专栏： C# 文章标签： c# efcore EntityFramework 分页

于 2021-09-14 15:22:49 首次发布

本文链接：https://blog.youkuaiyun.com/qq_37214567/article/details/120288325

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本文介绍了在.NET 8环境中如何使用PagedList类进行数据分页查询，包括Where和Select操作，并展示了PagedQueryableExtensions提供的ToPagedList方法及其异步版本。

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测试环境:
.Net 8

使用

public static PagedList<FrameWorkInfo> GetFrameWorks(int pageIndex = 1, int pageSize = 20)
{
    var db = new DefaultDbContext();
    
    return db.FrameWorkInfos
        .Where(a => a.IsDeleted == false) // 添加一些 where / select
        .ToPagedList(pageIndex, pageSize); // 最后调用封装的 ToPagedList
}

PagedQueryableExtensions.cs

using Microsoft.EntityFrameworkCore;
// 还有一些全局 using

namespace Demo.Extensions;

public static class PagedQueryableExtensions
{
    /// <summary>
    /// 分页拓展
    /// </summary>
    public static PagedList<TEntity> ToPagedList<TEntity>(this IQueryable<TEntity> entities, int pageIndex = 1, int pageSize = 20)
    {
        if (pageIndex <= 0) throw new InvalidOperationException($"{nameof(pageIndex)} must be a positive integer greater than 0.");

        var totalCount = entities.Count();
        var items = entities.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();
        var totalPages = (int)Math.Ceiling(totalCount / (double)pageSize);

        return new PagedList<TEntity>
        {
            PageIndex = pageIndex,
            PageSize = pageSize,
            Items = items,
            TotalCount = totalCount,
            TotalPages = totalPages,
            HasNextPages = pageIndex < totalPages,
            HasPrevPages = pageIndex - 1 > 0
        };
    }

    /// <summary>
    /// 分页拓展
    /// </summary>
    public static async Task<PagedList<TEntity>> ToPagedListAsync<TEntity>(this IQueryable<TEntity> entities, int pageIndex = 1, int pageSize = 20, CancellationToken cancellationToken = default)
    {
        if (pageIndex <= 0) throw new InvalidOperationException($"{nameof(pageIndex)} must be a positive integer greater than 0.");

        var totalCount = await entities.CountAsync(cancellationToken);
        var items = await entities.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToListAsync(cancellationToken);
        var totalPages = (int)Math.Ceiling(totalCount / (double)pageSize);

        return new PagedList<TEntity>
        {
            PageIndex = pageIndex,
            PageSize = pageSize,
            Items = items,
            TotalCount = totalCount,
            TotalPages = totalPages,
            HasNextPages = pageIndex < totalPages,
            HasPrevPages = pageIndex - 1 > 0
        };
    }
}


/// <summary>
/// 分页泛型集合
/// </summary>
/// <typeparam name="TEntity"></typeparam>
public class PagedList<TEntity>
{
    /// <summary>
    /// 页码
    /// </summary>
    public int PageIndex { get; set; }

    /// <summary>
    /// 页容量
    /// </summary>
    public int PageSize { get; set; }

    /// <summary>
    /// 总条数
    /// </summary>
    public int TotalCount { get; set; }

    /// <summary>
    /// 总页数
    /// </summary>
    public int TotalPages { get; set; }

    /// <summary>
    /// 当前页集合
    /// </summary>
    public IEnumerable<TEntity> Items { get; set; }

    /// <summary>
    /// 是否有上一页
    /// </summary>
    public bool HasPrevPages { get; set; }

    /// <summary>
    /// 是否有下一页
    /// </summary>
    public bool HasNextPages { get; set; }
}

/// <summary>
/// 分页集合
/// </summary>
public class PagedList : PagedList<object>
{
}