整合 Entity Framework Core 與 Pomelo MySQL

此次變更新增必要的命名空間，設置資料庫連接字串，並透過 `AddDbContext` 註冊 `ApplicationDbContext`。配置 MySQL 伺服器版本及相關選項，包括字符集和重試機制。根據開發環境啟用詳細錯誤和敏感數據日誌記錄，並添加控制台日誌記錄的過濾器。最後，應用程式被構建並運行。

Configurations.cs

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+using System;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
+using Models.Entities;
+using Configurations;
+
+public class ApplicationDbContext : DbContext
+{
+    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
+        : base(options)
+    {
+    }
+
+    public DbSet<Department> Departments => Set<Department>();
+    public DbSet<Role> Roles => Set<Role>();
+    public DbSet<Account> Accounts => Set<Account>();
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        base.OnModelCreating(modelBuilder);
+
+        // ®M¥Î©Ò¦³ EntityTypeConfiguration
+        modelBuilder.ApplyConfiguration(new DepartmentConfiguration());
+        modelBuilder.ApplyConfiguration(new RoleConfiguration());
+        modelBuilder.ApplyConfiguration(new AccountConfiguration());
+    }
+
+    public override int SaveChanges()
+    {
+        ApplyTimestamps();
+        return base.SaveChanges();
+    }
+
+    public override Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)
+    {
+        ApplyTimestamps();
+        return base.SaveChangesAsync(cancellationToken);
+    }
+
+    private void ApplyTimestamps()
+    {
+        var utcNow = DateTime.UtcNow;
+
+        foreach (var entry in ChangeTracker.Entries<BaseEntity>())
+        {
+            switch (entry.State)
+            {
+                case EntityState.Added:
+                    entry.Entity.CreatedAt = utcNow;
+                    entry.Entity.UpdatedAt = null;
+                    break;
+
+                case EntityState.Modified:
+                    // ÁקK­×§ï CreatedAt
+                    entry.Property(e => e.CreatedAt).IsModified = false;
+                    entry.Entity.UpdatedAt = utcNow;
+                    break;
+            }
+        }
+    }
+}

Configurations/AccountConfiguration.cs

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+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using Models.Entities;
+
+namespace Configurations
+{
+    public class AccountConfiguration : IEntityTypeConfiguration<Account>
+    {
+        public void Configure(EntityTypeBuilder<Account> builder)
+        {
+            builder.ToTable("accounts");
+
+            builder.HasKey(a => a.AccountId);
+
+            builder.Property(a => a.AccountId)
+                .HasColumnName("account_id");
+
+            builder.Property(a => a.Name)
+                .HasColumnName("name")
+                .IsRequired()
+                .HasMaxLength(100);
+
+            builder.Property(a => a.Username)
+                .HasColumnName("username")
+                .IsRequired()
+                .HasMaxLength(50);
+
+            builder.Property(a => a.Password)
+                .HasColumnName("password")
+                .IsRequired()
+                .HasMaxLength(256);
+
+            builder.Property(a => a.Email)
+                .HasColumnName("email")
+                .IsRequired()
+                .HasMaxLength(254);
+
+            builder.Property(a => a.DepartmentId)
+                .HasColumnName("department_id")
+                .IsRequired();
+
+            builder.Property(a => a.RoleId)
+                .HasColumnName("role_id")
+                .IsRequired();
+
+            builder.Property(a => a.Status)
+                .HasColumnName("status")
+                .HasConversion<string>()
+                .IsRequired()
+                .HasMaxLength(20);
+
+            builder.Property(a => a.CreatedAt)
+                .HasColumnName("created_at")
+                .IsRequired();
+
+            builder.Property(a => a.UpdatedAt)
+                .HasColumnName("updated_at");
+
+            builder.Property(a => a.ModifiedBy)
+                .HasColumnName("modified_by");
+
+            // 唯一索引
+            builder.HasIndex(a => a.Username)
+                .IsUnique()
+                .HasDatabaseName("UX_accounts_username");
+
+            builder.HasIndex(a => a.Email)
+                .IsUnique()
+                .HasDatabaseName("UX_accounts_email");
+
+            // 關聯與刪除行為
+            builder.HasOne(a => a.Department)
+                .WithMany(d => d.Accounts)
+                .HasForeignKey(a => a.DepartmentId)
+                .OnDelete(DeleteBehavior.Restrict);
+
+            builder.HasOne(a => a.Role)
+                .WithMany(r => r.Accounts)
+                .HasForeignKey(a => a.RoleId)
+                .OnDelete(DeleteBehavior.Restrict);
+
+            // 自參照外鍵：modified_by -> accounts.account_id (SET NULL)
+            builder.HasOne<Account>()
+                .WithMany()
+                .HasForeignKey(a => a.ModifiedBy)
+                .OnDelete(DeleteBehavior.SetNull);
+        }
+    }
+}

Configurations/DepartmentConfiguration.cs

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+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using Models.Entities;
+
+namespace Configurations
+{
+    public class DepartmentConfiguration : IEntityTypeConfiguration<Department>
+    {
+        public void Configure(EntityTypeBuilder<Department> builder)
+        {
+            builder.ToTable("departments");
+
+            builder.HasKey(d => d.DepartmentId);
+
+            builder.Property(d => d.DepartmentId)
+                .HasColumnName("department_id");
+
+            builder.Property(d => d.DepartmentName)
+                .HasColumnName("department_name")
+                .IsRequired()
+                .HasMaxLength(100);
+        }
+    }
+}

Configurations/RoleConfiguration.cs

@@ -0,0 +1,24 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using Models.Entities;
+
+namespace Configurations
+{
+    public class RoleConfiguration : IEntityTypeConfiguration<Role>
+    {
+        public void Configure(EntityTypeBuilder<Role> builder)
+        {
+            builder.ToTable("roles");
+
+            builder.HasKey(r => r.RoleId);
+
+            builder.Property(r => r.RoleId)
+                .HasColumnName("role_id");
+
+            builder.Property(r => r.RoleName)
+                .HasColumnName("role_name")
+                .IsRequired()
+                .HasMaxLength(50);
+        }
+    }
+}

Models/Entities/Account.cs

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+using System;
+
+namespace Models.Entities
+{
+    public class Account : BaseEntity
+    {
+        public int AccountId { get; set; }
+
+        public string Name { get; set; } = string.Empty;
+        public string Username { get; set; } = string.Empty;
+        public string Password { get; set; } = string.Empty;
+        public string Email { get; set; } = string.Empty;
+
+        public int DepartmentId { get; set; }
+        public int RoleId { get; set; }
+        public AccountStatus Status { get; set; }
+
+        public virtual Department? Department { get; set; }
+        public virtual Role? Role { get; set; }
+    }
+
+    public enum AccountStatus
+    {
+        Enabled,
+        Disabled,
+        Unverified
+    }
+}

Models/Entities/Department.cs

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+using System.Collections.Generic;
+
+namespace Models.Entities
+{
+    public class Department
+    {
+        public int DepartmentId { get; set; }
+        public string DepartmentName { get; set; } = string.Empty;
+
+        public virtual ICollection<Account> Accounts { get; set; } = new HashSet<Account>();
+    }
+}

Models/Entities/Role.cs

@@ -0,0 +1,12 @@
+using System.Collections.Generic;
+
+namespace Models.Entities
+{
+    public class Role
+    {
+        public int RoleId { get; set; }
+        public string RoleName { get; set; } = string.Empty;
+
+        public virtual ICollection<Account> Accounts { get; set; } = new HashSet<Account>();
+    }
+}

Program.cs

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+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+using Microsoft.Extensions.Logging;
+using Pomelo.EntityFrameworkCore.MySql.Infrastructure;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// 讀取連線字串
+var connectionString = builder.Configuration.GetConnectionString("DefaultConnection")
+    ?? throw new InvalidOperationException("Connection string 'DefaultConnection' not found.");
+
+// EF Core + Pomelo MySQL 註冊
+builder.Services.AddDbContext<ApplicationDbContext>(options =>
+{
+    var serverVersion = new MariaDbServerVersion(new Version(10, 6, 0));
+
+    options.UseMySql(connectionString, serverVersion, mySqlOptions =>
+    {
+        // 字元集設定
+        mySqlOptions.CharSet(CharSet.Utf8Mb4);
+        mySqlOptions.CharSetBehavior(CharSetBehavior.AppendToAllColumns);
+        // 可選：重試策略
+        mySqlOptions.EnableRetryOnFailure(5, TimeSpan.FromSeconds(10), null);
+    });
+
+    // 開發環境顯示更詳細的資料庫日誌
+    if (builder.Environment.IsDevelopment())
+    {
+        options.EnableDetailedErrors();
+        options.EnableSensitiveDataLogging();
+        options.LogTo(Console.WriteLine, LogLevel.Information, DbContextLoggerOptions.DefaultWithLocalTime);
+    }
+});
+
+// Logging（只在開發環境加強輸出 EF Core 訊息）
+if (builder.Environment.IsDevelopment())
+{
+    builder.Logging.AddConsole()
+        .AddFilter("Microsoft.EntityFrameworkCore.Database.Command", LogLevel.Information)
+        .AddFilter("Microsoft.EntityFrameworkCore.Infrastructure", LogLevel.Information);
+}
+
+var app = builder.Build();
+
+app.Run();