UpdateTime Type

Introduction

UpdateTime is a value type that encapsulates DateTimeOffset internally. It is used to represent a timestamp, usually indicating the last update time of a data record.

How to Use

Define a property of type UpdateTime in your entity, and the framework will automatically handle its value updates.

using NetCorePal.Extensions.Domain;
namespace YourNamespace;

public class Order : Entity<OrderId>, IAggregateRoot
{
    /// <summary>
    /// 
    /// </summary>
    protected Order()
    {
    }

    /// <summary>
    /// Update time
    /// </summary>
    public UpdateTime UpdateAt { get; private set; } = new UpdateTime(DateTimeOffset.UtcNow);
}

Control Database Field Properties

Use the [Column] attribute to control the database field name:

using NetCorePal.Extensions.Domain;
using System.ComponentModel.DataAnnotations.Schema;
namespace YourNamespace;

public class Order : Entity<OrderId>, IAggregateRoot
{
    /// <summary>
    /// 
    /// </summary>
    protected Order()
    {
    }

    /// <summary>
    /// Update time
    /// </summary>
    [Column(name:"update_at")]
    public UpdateTime UpdateAt { get; private set; } = new UpdateTime(DateTimeOffset.UtcNow);
}

Comparison Operations

The UpdateTime type supports comparison operators, allowing you to directly compare the temporal relationship between two UpdateTime values.

Supported Comparison Operators

• < (less than)
• > (greater than)
• <= (less than or equal to)
• >= (greater than or equal to)

Usage Examples

var time1 = new UpdateTime(DateTimeOffset.UtcNow);
await Task.Delay(100); // Wait for some time
var time2 = new UpdateTime(DateTimeOffset.UtcNow);

// Compare two update times
if (time1 < time2)
{
    Console.WriteLine("time1 is earlier than time2");
}

if (time2 > time1)
{
    Console.WriteLine("time2 is later than time1");
}

// Can be used for sorting or filtering
var orders = new List<Order>(); // Assume this is populated from database or other source
var recentOrders = orders.Where(o => o.UpdateAt >= new UpdateTime(DateTimeOffset.UtcNow.AddDays(-7))).ToList();

Important Notes for EF Core

When using UpdateTime comparison operators in EF Core LINQ queries, you cannot construct UpdateTime instances inside the expression. The UpdateTime construction must be done outside the query expression.

Incorrect (will not work with EF Core):

// ❌ This will fail with EF Core
var recentOrders = dbContext.Orders
    .Where(o => o.UpdateAt >= new UpdateTime(DateTimeOffset.UtcNow.AddDays(-7)))
    .ToList();

Correct (works with EF Core):

// ✅ Construct UpdateTime outside the expression
var sevenDaysAgo = new UpdateTime(DateTimeOffset.UtcNow.AddDays(-7));
var recentOrders = dbContext.Orders
    .Where(o => o.UpdateAt >= sevenDaysAgo)
    .ToList();