آموزش پیاده سازی Sort، Pagination و Search در جداول با ASP.net Core و 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 => (CurrentPage - 1) * PageSize + 1;

    public int LastRowOnPage => Math.Min(CurrentPage * PageSize, RowCount);
}

public class PagedResult<T> : PagedResultBase where T : class
{
    public IList<T> Results { get; set; }

    public PagedResult()
    {
        Results = new List<T>();
    }
}

public static class QueryableExtention
{
    public static PagedResult<T> GetPaged<T>(this IQueryable<T> query,
        int page, int pageSize) where T : class
    {
        var result = new PagedResult<T>
        {
            CurrentPage = page, PageSize = pageSize, 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;
    }
}

public class Student
{
    public int StudentId { get; set; }
    public string Name { get; set; }
    public string Family { get; set; }
}

public class AppDbContext : DbContext
{
    public AppDbContext(DbContextOptions<AppDbContext> options)
        : base(options)
    {
    }

    public DbSet<Student> Students { get; set; }
}

public class AppDbContext : DbContext
{
    public AppDbContext(DbContextOptions<AppDbContext> options)
        : base(options)
    {
    }

    public DbSet<Student> Students { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Student>().HasData(new Student[]
        {
            new Student {StudentId = 1, Name = "moein", Family = "Fazeli"},
            new Student {StudentId = 2, Name = "omid", Family = "gholami"},
            new Student {StudentId = 3, Name = "sara", Family = "saravi"},
            new Student {StudentId = 4, Name = "fateme", Family = "mosavi"},
            new Student {StudentId = 5, Name = "jodi", Family = "abot"},
            new Student {StudentId = 6, Name = "sobasa", Family = "karaeer"},
            new Student {StudentId = 7, Name = "ahmad", Family = "hoseeini"},
            new Student {StudentId = 8, Name = "mohammad", Family = "bahrami"},
            new Student {StudentId = 9, Name = "saeed", Family = "sadeghi"},
            new Student {StudentId = 10, Name = "sajad", Family = "saheri"},
            new Student {StudentId = 11, Name = "sami", Family = "sarvari"},
            new Student {StudentId = 12, Name = "bano", Family = "mahmodi"},
            new Student {StudentId = 13, Name = "mahdie", Family = "maghsoodi"},
            new Student {StudentId = 14, Name = "shahriar", Family = "asadi"}
        });
    }
}

{
  "AppSettings": {
    "DbConnection": "Server=(localdb)\\MSSQLLocalDB;Database=Student;Trusted_Connection=True;MultipleActiveResultSets=true"
  }
}

public class AppSettings
{
    public string Secret { get; set; }
    public string DbConnection { get; set; }
}

public class Startup
{
    private readonly IConfiguration _configuration;

    public Startup(IConfiguration configuration)
    {
        _configuration = configuration;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        // configure strongly typed settings objects
        var appSettingsSection = _configuration.GetSection("AppSettings");
        services.Configure<AppSettings>(appSettingsSection);
        var appSettings = appSettingsSection.Get<AppSettings>();

        // configure Dbcontext service
        services.AddDbContext<AppDbContext>(options =>
            options.UseSqlServer(appSettings.DbConnection)
        );

        services.AddMvc();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseCors(options =>
        {
            options.AllowAnyHeader();
            options.AllowAnyMethod();
            options.AllowAnyOrigin();
        });
        app.UseMvc();
    }
}

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public interface IStudentService
{
    void FilterAll(string term);
    void Sort(string filed, string sortDirection);
    PagedResult<Student> GetStudents(int page, int pageSize);
}

public class StudentService : IStudentService
{
    private IQueryable<Student> _students;

    public StudentService(AppDbContext dbContext)
    {
        _students = dbContext.Students;
    }

    public void FilterAll(string term)
    {
        _students = _students.Where(std => std.Name.Contains(term) || std.Family.Contains(term));
    }

    public void Sort(string filed, string sortDirection)
    {
        switch (filed)
        {
            case "name" when sortDirection == "desc":
                _students = _students.OrderByDescending(x => x.Name);
                break;
            case "name" when sortDirection == "asc":
                _students = _students.OrderBy(x => x.Name);
                break;
            case "family" when sortDirection == "desc":
                _students = _students.OrderByDescending(x => x.Family);
                break;
            case "family" when sortDirection == "asc":
                _students = _students.OrderBy(x => x.Family);
                break;
        }
    }

    public PagedResult<Student> GetStudents(int page, int pageSize)
    {
        return _students.GetPaged(page, pageSize);
    }
}

services.AddScoped<IStudentService, StudentService>();

[Route("api/[Controller]")]
[ApiController]
public class StudentController : Controller
{
    private readonly IStudentService _studentService;

    public StudentController(IStudentService studentService)
    {
        _studentService = studentService;
    }

    [HttpGet]
    public PagedResult<Student> Index(string filed, string term,
        int page = 1, int pageSize = 4, string sortDirection = "")
    {
        if (term != null)
        {
            _studentService.FilterAll(term);
        }

        if (filed != null)
        {
            _studentService.Sort(filed, sortDirection);
        }

        return _studentService.GetStudents(page, pageSize);
    }
}