SteamTools/System.Common.CoreLib/Application/Models/PagedModel.cs

using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using MPKey = MessagePack.KeyAttribute;
using MPObj = MessagePack.MessagePackObjectAttribute;
using N_JsonProperty = Newtonsoft.Json.JsonPropertyAttribute;
using S_JsonProperty = System.Text.Json.Serialization.JsonPropertyNameAttribute;

namespace System.Application.Models
{
    /// <inheritdoc cref="IPagedModel"/>
    [MPObj]
    [Serializable]
    [DebuggerDisplay("{DebuggerDisplay(),nq}")]
    public sealed class PagedModel<T> : IPagedModel<T>, IReadOnlyPagedModel<T>
    {
        string DebuggerDisplay() => $"Current: {Current}, Total: {Total}, Count: {mDataSource?.Count ?? 0}, PageSize: {PageSize}";

        List<T>? mDataSource;

        [MPKey(0)]
        [N_JsonProperty("0")]
        [S_JsonProperty("0")]
        public List<T> DataSource
        {
            get
            {
                if (mDataSource == null) mDataSource = new List<T>();
                return mDataSource;
            }
            set
            {
                mDataSource = value;
            }
        }

        [MPKey(1)]
        [N_JsonProperty("1")]
        [S_JsonProperty("1")]
        public int Current { get; set; } = IPagedModel.DefaultCurrent;

        [MPKey(2)]
        [N_JsonProperty("2")]
        [S_JsonProperty("2")]
        public int PageSize { get; set; } = IPagedModel.DefaultPageSize;

        [MPKey(3)]
        [N_JsonProperty("3")]
        [S_JsonProperty("3")]
        public int Total { get; set; }

        bool IExplicitHasValue.ExplicitHasValue()
        {
            return Total > 0 && PageSize > 0 && Current > 0 &&
                Current <= ((IPagedModel)this).PageCount &&
                mDataSource.Any_Nullable();
        }

        IReadOnlyList<T> IReadOnlyPagedModel<T>.DataSource => DataSource;

        IList<T> IPagedModel<T>.DataSource
        {
            get => DataSource;
            set => DataSource = value is List<T> list ? list : value.ToList();
        }
    }
}