paging entity framework core code example

Example 1: paging entity framework core

public abstract class PagedResultBase
{
    public int CurrentPage { get; set; } 
    public int PageCount { get; set; } 
    public int PageSize { get; set; } 
    public int RowCount { get; set; }
 
    public int FirstRowOnPage
    {
 
        get { return (CurrentPage - 1) * PageSize + 1; }
    }
 
    public int LastRowOnPage
    {
        get { return Math.Min(CurrentPage * PageSize, RowCount); }
    }
}
 
public class PagedResult : PagedResultBase where T : class
{
    public IList Results { get; set; }
 
    public PagedResult()
    {
        Results = new List();
    }
}

Example 2: paging entity framework core

public static PagedResult GetPaged(this IQueryable query, 
                                         int page, int pageSize) where T : class
{
     var result = new PagedResult();
     result.CurrentPage = page;
     result.PageSize = pageSize;
     result.RowCount = query.Count();


     var pageCount = (double)result.RowCount / pageSize;
     result.PageCount = (int)Math.Ceiling(pageCount);
 
     var skip = (page - 1) * pageSize;     
     result.Results = query.Skip(skip).Take(pageSize).ToList();
 
     return result;
}

Example 3: how manage pagination ef core

public static class PaginationService
{

    public static async Task> GetPagination(IQueryable query, int page, string orderBy, bool orderByDesc, int pageSize) where T : class
    {
        Pagination pagination = new Pagination
        {
            TotalItems = query.Count(),
            PageSize = pageSize,
            CurrentPage = page,
            OrderBy = orderBy,
            OrderByDesc = orderByDesc
        };

        int skip = (page - 1) * pageSize;
        var props = typeof(T).GetProperties();
        var orderByProperty = props.FirstOrDefault(n => n.GetCustomAttribute()?.OrderBy == orderBy);


         if (orderByProperty == null)
        {
            throw new Exception($"Field: '{orderBy}' is not sortable");
        }

        if (orderByDesc)
        {
            pagination.Result = await query
                .OrderByDescending(x => orderByProperty.GetValue(x))
                .Skip(skip)
                .Take(pageSize)
                .ToListAsync();

            return pagination;
        }
        pagination.Result = await query
            .OrderBy(x => orderByProperty.GetValue(x))
            .Skip(skip)
            .Take(pageSize)
            .ToListAsync();

        return pagination;
    }
}

Example 4: how manage pagination ef core

[HttpGet]
    public async Task GetUsers([FromQuery] string orderBy, [FromQuery] bool orderByDesc, [FromQuery] int page, [FromQuery] int size)
    {
        var query = _context.User.AsQueryable();
        try
        {
            var list = await PaginationService.GetPagination(query, page, orderBy, orderByDesc, size);
            return new JsonResult(list);
        }
        catch (Exception e)
        {
            return new BadRequestObjectResult(e.Message);
        }
    }