SPMS.Domain/Common/ErrorCodes.cs

@@ -59,4 +59,10 @@ public static class ErrorCodes
     public const string FileNotFound = "181";
     public const string FileTypeNotAllowed = "182";
     public const string FileSizeExceeded = "183";
+
+    // === Tag (9) ===
+    public const string TagNotFound = "191";
+    public const string TagNameDuplicate = "192";
+    public const string TagNameImmutable = "193";
+    public const string TagLimitExceeded = "194";
 }

SPMS.Domain/Entities/Service.cs

@@ -35,4 +35,5 @@ public class Service : BaseEntity
     public ICollection<ServiceIp> ServiceIps { get; set; } = new List<ServiceIp>();
     public ICollection<Device> Devices { get; set; } = new List<Device>();
     public ICollection<Message> Messages { get; set; } = new List<Message>();
+    public ICollection<Tag> TagList { get; set; } = new List<Tag>();
 }

SPMS.Domain/Entities/Tag.cs

@@ -0,0 +1,15 @@
+namespace SPMS.Domain.Entities;
+
+public class Tag : BaseEntity
+{
+    public long ServiceId { get; set; }
+    public string Name { get; set; } = string.Empty;
+    public string? Description { get; set; }
+    public DateTime CreatedAt { get; set; }
+    public long CreatedBy { get; set; }
+    public DateTime? UpdatedAt { get; set; }
+
+    // Navigation
+    public Service Service { get; set; } = null!;
+    public Admin CreatedByAdmin { get; set; } = null!;
+}

SPMS.Domain/Interfaces/ITagRepository.cs

@@ -0,0 +1,9 @@
+using SPMS.Domain.Entities;
+
+namespace SPMS.Domain.Interfaces;
+
+public interface ITagRepository : IRepository<Tag>
+{
+    Task<Tag?> GetByIdWithServiceAsync(long id);
+    Task<bool> ExistsInServiceAsync(long serviceId, string name);
+}

SPMS.Infrastructure/AppDbContext.cs

@@ -25,6 +25,7 @@ public class AppDbContext : DbContext
     public DbSet<Banner> Banners => Set<Banner>();
     public DbSet<Faq> Faqs => Set<Faq>();
     public DbSet<AppConfig> AppConfigs => Set<AppConfig>();
+    public DbSet<Tag> Tags => Set<Tag>();
 
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {

SPMS.Infrastructure/DependencyInjection.cs

@@ -43,6 +43,7 @@ public static class DependencyInjection
         services.AddScoped<IPushSendLogRepository, PushSendLogRepository>();
         services.AddScoped<IDailyStatRepository, DailyStatRepository>();
         services.AddScoped<IWebhookLogRepository, WebhookLogRepository>();
+        services.AddScoped<ITagRepository, TagRepository>();
 
         // External Services
         services.AddScoped<IJwtService, JwtService>();

SPMS.Infrastructure/Migrations/20260225083135_AddTagTable.cs

@@ -0,0 +1,67 @@
+using System;
+using Microsoft.EntityFrameworkCore.Metadata;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace SPMS.Infrastructure.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddTagTable : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "Tag",
+                columns: table => new
+                {
+                    Id = table.Column<long>(type: "bigint", nullable: false)
+                        .Annotation("MySql:ValueGenerationStrategy", MySqlValueGenerationStrategy.IdentityColumn),
+                    ServiceId = table.Column<long>(type: "bigint", nullable: false),
+                    Name = table.Column<string>(type: "varchar(50)", maxLength: 50, nullable: false)
+                        .Annotation("MySql:CharSet", "utf8mb4"),
+                    Description = table.Column<string>(type: "varchar(200)", maxLength: 200, nullable: true)
+                        .Annotation("MySql:CharSet", "utf8mb4"),
+                    CreatedAt = table.Column<DateTime>(type: "datetime(6)", nullable: false),
+                    CreatedBy = table.Column<long>(type: "bigint", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "datetime(6)", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_Tag", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_Tag_Admin_CreatedBy",
+                        column: x => x.CreatedBy,
+                        principalTable: "Admin",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                    table.ForeignKey(
+                        name: "FK_Tag_Service_ServiceId",
+                        column: x => x.ServiceId,
+                        principalTable: "Service",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                })
+                .Annotation("MySql:CharSet", "utf8mb4");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Tag_CreatedBy",
+                table: "Tag",
+                column: "CreatedBy");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Tag_ServiceId_Name",
+                table: "Tag",
+                columns: new[] { "ServiceId", "Name" },
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "Tag");
+        }
+    }
+}

SPMS.Infrastructure/Migrations/AppDbContextModelSnapshot.cs

@@ -836,6 +836,45 @@ namespace SPMS.Infrastructure.Migrations
                     b.ToTable("SystemLog", (string)null);
                 });
 
+            modelBuilder.Entity("SPMS.Domain.Entities.Tag", b =>
+                {
+                    b.Property<long>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("bigint");
+
+                    MySqlPropertyBuilderExtensions.UseMySqlIdentityColumn(b.Property<long>("Id"));
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<long>("CreatedBy")
+                        .HasColumnType("bigint");
+
+                    b.Property<string>("Description")
+                        .HasMaxLength(200)
+                        .HasColumnType("varchar(200)");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("varchar(50)");
+
+                    b.Property<long>("ServiceId")
+                        .HasColumnType("bigint");
+
+                    b.Property<DateTime?>("UpdatedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CreatedBy");
+
+                    b.HasIndex("ServiceId", "Name")
+                        .IsUnique();
+
+                    b.ToTable("Tag", (string)null);
+                });
+
             modelBuilder.Entity("SPMS.Domain.Entities.WebhookLog", b =>
                 {
                     b.Property<long>("Id")
@@ -1102,6 +1141,25 @@ namespace SPMS.Infrastructure.Migrations
                     b.Navigation("Service");
                 });
 
+            modelBuilder.Entity("SPMS.Domain.Entities.Tag", b =>
+                {
+                    b.HasOne("SPMS.Domain.Entities.Admin", "CreatedByAdmin")
+                        .WithMany()
+                        .HasForeignKey("CreatedBy")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.HasOne("SPMS.Domain.Entities.Service", "Service")
+                        .WithMany("TagList")
+                        .HasForeignKey("ServiceId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.Navigation("CreatedByAdmin");
+
+                    b.Navigation("Service");
+                });
+
             modelBuilder.Entity("SPMS.Domain.Entities.WebhookLog", b =>
                 {
                     b.HasOne("SPMS.Domain.Entities.Service", "Service")
@@ -1120,6 +1178,8 @@ namespace SPMS.Infrastructure.Migrations
                     b.Navigation("Messages");
 
                     b.Navigation("ServiceIps");
+
+                    b.Navigation("TagList");
                 });
 #pragma warning restore 612, 618
         }

SPMS.Infrastructure/Persistence/Configurations/TagConfiguration.cs

@@ -0,0 +1,34 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using SPMS.Domain.Entities;
+
+namespace SPMS.Infrastructure.Persistence.Configurations;
+
+public class TagConfiguration : IEntityTypeConfiguration<Tag>
+{
+    public void Configure(EntityTypeBuilder<Tag> builder)
+    {
+        builder.ToTable("Tag");
+
+        builder.HasKey(e => e.Id);
+        builder.Property(e => e.Id).ValueGeneratedOnAdd();
+
+        builder.Property(e => e.Name).HasMaxLength(50).IsRequired();
+        builder.Property(e => e.Description).HasMaxLength(200);
+        builder.Property(e => e.CreatedAt).IsRequired();
+        builder.Property(e => e.CreatedBy).IsRequired();
+        builder.Property(e => e.UpdatedAt);
+
+        builder.HasOne(e => e.Service)
+            .WithMany(s => s.TagList)
+            .HasForeignKey(e => e.ServiceId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.HasOne(e => e.CreatedByAdmin)
+            .WithMany()
+            .HasForeignKey(e => e.CreatedBy)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.HasIndex(e => new { e.ServiceId, e.Name }).IsUnique();
+    }
+}

SPMS.Infrastructure/Persistence/Repositories/TagRepository.cs

@@ -0,0 +1,18 @@
+using Microsoft.EntityFrameworkCore;
+using SPMS.Domain.Entities;
+using SPMS.Domain.Interfaces;
+
+namespace SPMS.Infrastructure.Persistence.Repositories;
+
+public class TagRepository : Repository<Tag>, ITagRepository
+{
+    public TagRepository(AppDbContext context) : base(context) { }
+
+    public async Task<Tag?> GetByIdWithServiceAsync(long id)
+        => await _dbSet
+            .Include(t => t.Service)
+            .FirstOrDefaultAsync(t => t.Id == id);
+
+    public async Task<bool> ExistsInServiceAsync(long serviceId, string name)
+        => await _dbSet.AnyAsync(t => t.ServiceId == serviceId && t.Name == name);
+}