更新行 - 检查它是否存在 否则使用实体框架插入逻辑

Question

What is the best way to implement update row if it exists, else insert new row logic using Entity Framework?

Below is what I have done so far. I want to check, if any field in the existing employee database has changed then only update that record or if it is a new one add as a new row.

Ex- Update the job title if it has changed, or add it as a new line if a new employee is added

//DbContext

public class DataContext : DbContext
{
    public static string providerName = "System.Data.SqlClient";
    public DbSet<DisplayAPIDataEmployee>? Employee { get; set; }

    protected override void OnConfiguring(Microsoft.EntityFrameworkCore.DbContextOptionsBuilder optionBuilder)
    {
        optionBuilder.UseSqlServer("Server=;Initial Catalog = ;user id = ;password=");
    }

    protected override void OnModelCreating(Microsoft.EntityFrameworkCore.ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<DisplayAPIDataEmployee>().ToTable("Employee", e => e.IsTemporal());
    }
}

// Data model

[Table("Employee")]
public class DisplayAPIDataEmployee
{

    public DisplayAPIDataEmployee()
    {
        createdOn = DateTime.Now;
    }

    public DateTime ?createdOn { get; set; }
    public string ?displayName { get; set; }
    public string ?shortBirthDate { get; set; }

    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public string employee_id { get; set; }

}

Answer 1

Inject the DbContext class into your controller and handle your logic in a controller method

private readonly DataContext _context;

public Controller(DataContext _context) => this._context = _context;
...
// rest of your code
...
public void Test(string employee_id) {
    using DataContext dbContext = _context;
    using IDbContextTransaction transaction = dbContext.Database.BeginTransaction();

    try {
        DisplayAPIDataEmployee? employee = dbContext.Employee.FirstOrDefault(e => e.employee_id.Equals(employee_id));

        if (employee is null) {
            // add employee
            DisplayAPIDataEmployee add_employee = new(); //
            add_employee.employee_id = "";

            dbContext.Employee.AddRange(add_employee);
            dbContext.SaveChanges();
        }
        else {
            employee.employee_id = ""; // update employee property value

            dbContext.SaveChanges(); // entity 'employee' is tracked by EF Core and any saved changes to it is reflected to entity in Database.
        }

        transaction.Commit(); // commit all save changes if successful
    }
    catch (Exception ex)
    {
        transaction.Rollback(); // rollback in case of errors
        dbContext.ChangeTracker.Clear();

        // Log error
    }
}