[EF6][SQLite] SQLite Code First 和 Migration (2)

2020-02-14

779
0
SQLite
2020-10-07

續上篇，[EF6][SQLite] SQLite Code First 和 Migration，那篇使用的 System.Data.SQLite.EF6.Migrations 套件，不過在 .NET Framework 4 的環境下一直有問題，不得已的情況下要改用 SQLite.CodeFirst

開發環境

VS 2019
.NET Framework 4.0
EF 6.3
System.Data.SQLite 1.0.112.0

實作

安裝套件

Install-Package System.Data.SQLite

Install-Package SQLite.CodeFirst

packages.config 相依套件如下

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="EntityFramework" version="6.3.0" targetFramework="net40" />
  <package id="SQLite.CodeFirst" version="1.5.3.29" targetFramework="net40" />
  <package id="System.Data.SQLite" version="1.0.112.0" targetFramework="net40" />
  <package id="System.Data.SQLite.Core" version="1.0.112.0" targetFramework="net40" />
  <package id="System.Data.SQLite.EF6" version="1.0.112.0" targetFramework="net40" />
  <package id="System.Data.SQLite.Linq" version="1.0.112.0" targetFramework="net40" />
</packages>

組態

增加 Provider

<entityFramework>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
      <provider invariantName="System.Data.SQLite.EF6" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
      <provider invariantName="System.Data.SQLite" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
    </providers>
</entityFramework>

增加連線字串

<connectionStrings>
    <add name="DefaultConnection" connectionString="data source=lab.db" providerName="System.Data.SQLite" />
</connectionStrings>

POCO

[Table("Employee")]
public class Employee
{
    [Required]
    [Key]
    public Guid Id { get; set; }
 
    [StringLength(100)]
    public string Name { get; set; }
 
    //public int Age { get; set; }
}

LabDbContext

這裡在 OnModelCreating 調用 new SqliteDropCreateDatabaseWhenModelChanges<LabDbContext>(modelBuilder)

public class LabDbContext : DbContext
{
    private static readonly bool[] s_migrated = {false};
 
    public DbSet<Employee> Employees { get; set; }
 
    public LabDbContext() : base("DefaultConnection")
    {
    }
 
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        if (!s_migrated[0])
        {
            lock (s_migrated)
            {
                if (!s_migrated[0])
                {
                    var initializer = new SqliteDropCreateDatabaseWhenModelChanges<LabDbContext>(modelBuilder);
                    Database.SetInitializer(initializer);
 
                    s_migrated[0] = true;
                }
            }
        }
    }
}

還原測試資料庫

為了觀察 Auto Magration 運作是否正常，只砍測試資料，就不砍 DB 檔案了

[TestCleanup]
public void After()
{
    using (var db = new LabDbContext())
    {
        //db.Database.ExecuteSqlCommand("delete from Identity;");
 
        db.Database.ExecuteSqlCommand("delete from Employee;");
    }
}
 
[TestInitialize]
public void Before()
{
    using (var db = new LabDbContext())
    {
        //db.Database.ExecuteSqlCommand("delete from Identity;");
 
        db.Database.ExecuteSqlCommand("delete from Employee;");
    }
}

新增案例

[TestMethod]
public void Insert()
{
    var toDb = new Employee
    {
        Id   = Guid.NewGuid(),
        Name = "yao",
        //Age = 18
    };
    using (var db = new LabDbContext())
    {
        db.Employees.Add(toDb);
        var count = db.SaveChanges();
        Assert.AreEqual(1, count);
    }
}

資料庫結構如下，使用 SQLite.CodeFirst 的 Migration 資料表叫 History_XXX