.net 6 Core MVC Paging for a navigation property

Question

I am trying to build an application like in the tutorial in Microsoft: https://docs.microsoft.com/en-us/aspnet/core/data/ef-mvc/sort-filter-page?view=aspnetcore-6.0

So i have a model like this:

using ABCrm2.Data.Account;
using ABCrm2.Models.Allgemein;
using ABCrm2.Models.Vertrieb;
using Microsoft.EntityFrameworkCore;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Diagnostics.CodeAnalysis;

namespace ABCrm2.Models.Stammdaten
{
    public class Land
    {
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        [Key]  
        public int Id { get; set; }
      
        [NotNull]
        [MaxLength(40)]            
        public string? Landbezeichnung { get; set; }
                
        [MaxLength(3)]
        public string? LandKurz { get; set; }

        [Required]
        [NotNull]
        [MaxLength(10)]            
        public string? LandVorwahl { get; set; } 

        public DateTime? ErstellDatumZeit { get; set; }            
        public DateTime? ÄnderDatumZeit { get; set; } = DateTime.Now;    

        public bool Aktiv { get; set; }

        [Timestamp]
        public byte[] RowVersion { get; set; }

        public ICollection? Bundesländer { get; set; }

    }
}

using Microsoft.EntityFrameworkCore;
using System.ComponentModel.DataAnnotations.Schema;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;

namespace ABCrm2.Models.Stammdaten
{
    public class Bundesland
    {
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        [Key]
        public int Id { get; set; }

        [Required]
        [NotNull]
        [MaxLength(30)]            
        public string BundeslandText { get; set; }

        [ForeignKey("Länder")]
        [Required]
        [NotNull]
        public int LandId { get; set; }            
        public Land? Länder { get; set; }

        public bool Aktiv { get; set; }

        public DateTime? ErstellDatumZeit { get; set; }
        public DateTime? ÄnderDatumZeit { get; set; } = DateTime.Now;

        [Timestamp]
        public byte[] RowVersion { get; set; }
    }
}

in the Index of Land i use the helper PaginatedList.cs like in the tutorial:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;

namespace ContosoUniversity
{
    public class PaginatedList : List
    {
        public int PageIndex { get; private set; }
        public int TotalPages { get; private set; }

        public PaginatedList(List items, int count, int pageIndex, int pageSize)
        {
            PageIndex = pageIndex;
            TotalPages = (int)Math.Ceiling(count / (double)pageSize);

            this.AddRange(items);
        }

        public bool HasPreviousPage => PageIndex > 1;

        public bool HasNextPage => PageIndex < TotalPages;

        public static async Task> CreateAsync(IQueryable source, int pageIndex, int pageSize)
        {
            var count = await source.CountAsync();
            var items = await source.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToListAsync();
            return new PaginatedList(items, count, pageIndex, pageSize);
        }
    }
}

in the details of land i would like to have the land and the list of countries (Bundesland)

Controller Part:

public async Task Details(int? id, int? seiteBL)
        {
            if (id == null || _context.Länder == null)
            {
                return NotFound();
            }            

            var land = await _context.Länder
                .AsNoTracking()
                .Include(a => a.Bundesländer.Where(s => s.Aktiv.Equals(true)))
                .FirstOrDefaultAsync(m => m.Id == id);
                        
            if (land == null)
            {
                return NotFound();
            }
            var pageSizeBL = Configuration.GetValue("PageSize", 16);
            double AnzahlTrefferBL = land.Bundesländer.Count();
            int? aktuelleSeiteBL = seiteBL;
            if (aktuelleSeiteBL == null)
            {
                aktuelleSeiteBL = 1;
            }
            ViewData["AnzahlTrefferBL"] = land.Bundesländer.Count();
            ViewData["AnzahlSeitenBL"] = (int)Math.Ceiling(AnzahlTrefferBL / pageSizeBL);
            ViewData["AktuelleSeiteBL"] = aktuelleSeiteBL;

            //how do i get the paging of Bundesländer?

            return View(land);
        }

the view:

@using ABCrm2.Helper
@using ABCrm2.Models.Stammdaten
@model Land
@{
    ViewData["Title"] = "Land anzeigen";
}


    
    
                    
                             
                                
            
        
        
            Land anzeigen
            
         
        
        
    
    
        
            
                
            
            
                
            
            
                
            
        
        
            
                
                    
                        
                            
                                
                                
                            
                        
                    
                                        
                        
                            
                                
                                                            
                            
                        
                    
                        
                            
                            
                            
                        
                    

                    
                        
                        
                    
                                    
                    
                        
                            
                                
                                                            
                            
                        
                    
                        
                            
                            
                            
                        
                    
                
             @*row*@
            
                                    
                    
                                                    
                            @Html.DisplayNameFor(model => model.ErstellDatumZeit)                                                      
                                                 
                                                    
                            @Html.DisplayNameFor(model => model.ÄnderDatumZeit)                                               
                        
                     
                     
                                                                                
                            @Html.DisplayFor(model => model.ErstellDatumZeit)                           
                                                 
                                                                                
                            @Html.DisplayFor(model => model.ÄnderDatumZeit)                          
                        
                     
                
             @*row*@
        
        
            
                
                       
                        
                        
                        @if (Model.Bundesländer.Count() > 0)
                        {
                                   

                            @foreach (var item in Model.Bundesländer)
                            {

                                
                            }
                        }
                        else
                        {
                            
                        }
                    
                    
                        
                            
                                Bundesländer
                            
                            
                            
                        
                    
                    
                        
                            
                                
                                    
                                        
                                    
                                    
                                        
                                    
                                    
                                        
                                    
                                
                             
                            
                                Aktiv
                            
                            
                                Id
                            
                            
                                Bundesland
                                                        
                            
                                Änderungsdatum
                            
                            
                                Erstelldatum
                            
                        
                    
                    
                                    
                                        
                                            
                                                
                                            
                                            
                                                
                                            
                                            
                                                
                                            
                                        
                                    
                                    @Html.DisplayFor(modelItem => item.Aktiv)
                                    @Html.DisplayFor(modelItem => item.Id)
                                    @Html.DisplayFor(modelItem => item.BundeslandText)
                                    
                                    @Html.DisplayFor(modelItem => item.ÄnderDatumZeit)
                                    @Html.DisplayFor(modelItem => item.ErstellDatumZeit)
                                

                                keine Datensätze vorhanden

it is all ok - the Bundesländer are listet complete - but how to do paging there for the navigation property by using the helper PaginatedList.cs ??

.net 6 Core MVC Paging for a navigation property

0 Answers