public enum GridEditNewRowPosition

@using Microsoft.EntityFrameworkCore
@inject IDbContextFactory<NorthwindContext> NorthwindContextFactory
@implements IDisposable

<DxGrid Data="Data"
        KeyFieldName="EmployeeId"
        EditModelSaving="OnEditModelSaving"
        DataItemDeleting="OnDataItemDeleting"
        CustomizeEditModel="OnCustomizeEditModel"
        EditMode="GridEditMode.EditCell"
        EditNewRowPosition="GridEditNewRowPosition.FixedOnTop">
    <Columns>
        <DxGridDataColumn FieldName="TitleOfCourtesy" Caption="Courtesy Title" />
        <DxGridDataColumn FieldName="FirstName" />
        <DxGridDataColumn FieldName="LastName" />
        <DxGridDataColumn FieldName="Title" />
        <DxGridCommandColumn Width="30px" EditButtonVisible="false" SaveButtonVisible="false" />
    </Columns>
</DxGrid>

@code {
    IEnumerable<Employee> Data { get; set; }
    NorthwindContext Northwind { get; set; }

    protected override async Task OnInitializedAsync() {
        Northwind = NorthwindContextFactory.CreateDbContext();
        Data = await Northwind.Employees.ToListAsync();
    }

    void OnCustomizeEditModel(GridCustomizeEditModelEventArgs e) {
        if(e.IsNew) {
            var editModel = (Employee)e.EditModel;
            editModel.EmployeeId = Data.Max(x => x.EmployeeId) + 1;
        }
    }

    async Task OnEditModelSaving(GridEditModelSavingEventArgs e) {
        var editModel = (Employee)e.EditModel;
        if (e.IsNew)
            await Northwind.AddAsync(editModel);
        else
            e.CopyChangesToDataItem();
        // Post changes to the database.
        await Northwind.SaveChangesAsync();
        // Reload the entire Grid.
        Data = await Northwind.Employees.ToListAsync();
    }

    async Task OnDataItemDeleting(GridDataItemDeletingEventArgs e) {
        // Remove the data item from the database.
        Northwind.Remove(e.DataItem);
        await Northwind.SaveChangesAsync();
        // Reload the entire Grid.
        Data = await Northwind.Employees.ToListAsync();
    }

    public void Dispose() {
        Northwind?.Dispose();
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace Grid.Northwind {
    public partial class Employee {
        public int EmployeeId { get; set; }
        [Required]
        public string LastName { get; set; }
        [Required]
        public string FirstName { get; set; }
        [Required]
        public string Title { get; set; }
        public string TitleOfCourtesy { get; set; }
        public Nullable BirthDate { get; set; }
        [Required]
        [Range(typeof(DateTime), "1/1/2000", "1/1/2020",
        ErrorMessage = "HireDate must be between {1:d} and {2:d}")]
        public Nullable HireDate { get; set; }
        public string Address { get; set; }
        public string City { get; set; }
        public string Region { get; set; }
        public string PostalCode { get; set; }
        public string Country { get; set; }
        public string HomePhone { get; set; }
        public string Extension { get; set; }
        public byte[] Photo { get; set; }
        public string Notes { get; set; }
        public Nullable<int> ReportsTo { get; set; }
        public string PhotoPath { get; set; }
        public virtual ICollection<Order> Orders { get; set; }
        public string Text => $"{FirstName} {LastName} ({Title})";
        public string ImageFileName => $"Employees/{EmployeeId}.jpg";
    }
}

using Microsoft.EntityFrameworkCore;
#nullable disable

namespace Grid.Northwind {
    public partial class NorthwindContext : DbContext {

        public NorthwindContext(DbContextOptions<NorthwindContext> options)
            : base(options) {
        }
        // ...
        public virtual DbSet<Employee> Employees { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) {
            if(!optionsBuilder.IsConfigured) {
                optionsBuilder.UseSqlServer("Server=.\\sqlexpress;Database=Northwind;Integrated Security=true");
            }
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder) {
            modelBuilder.HasAnnotation("Relational:Collation", "SQL_Latin1_General_CP1_CI_AS");
            // ...
            modelBuilder.Entity<Employee>(entity => {
                entity.HasIndex(e => e.TitleOfCourtesy, "TitleOfCourtesy");
                entity.HasIndex(e => e.EmployeeId, "EmployeeId");
                entity.HasIndex(e => e.LastName, "LastName");
                entity.HasIndex(e => e.FirstName, "FirstName");
                entity.HasIndex(e => e.Title, "Title");
                entity.HasIndex(e => e.BirthDate, "BirthDate");
                entity.HasIndex(e => e.HireDate, "HireDate");
                entity.HasIndex(e => e.Notes, "Notes");
            });
            OnModelCreatingPartial(modelBuilder);
        }

        partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
    }
}

using Microsoft.EntityFrameworkCore;
// ...
builder.Services.AddDbContextFactory<NorthwindContext>((sp, options) ={
    var env = sp.GetRequiredService<IWebHostEnvironment>();
    var dbPath = Path.Combine(env.ContentRootPath, "Northwind-5e44b51f.mdf");
    options.UseSqlServer("Server=(localdb)\\MSSQLLocalDB;Integrated Security=true;AttachDbFileName=" + dbPath);
});