仅插入EF代码优先数据数据一次

Question

在我的ef代码优先应用程序中，我正在播种超级用户基础数据。稍后，它的值可以从应用程序接口更改。

但是我面临的问题 - 每次运行应用程序时，此种子数据每次都会刷新。我不想要这个重置。有什么办法避免这种情况吗？

//This is my DatabaseContext.cs -
public partial class DatabaseContext : DbContext
{
    public DatabaseContext() : base("name=EntityConnection")
    {
       Database.SetInitializer(new MigrateDatabaseToLatestVersion<DatabaseContext, Migrations.Configuration>()); 
    }
}
//This is my Configuration.cs-
internal sealed class Configuration : DbMigrationsConfiguration<DatabaseContext>
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = true;
        AutomaticMigrationDataLossAllowed = false;
    }
    protected override void Seed(DatabaseContext context)
    {
        User user = new User()
            {
                UserId = 1,
                EmailAddress = "[e-mail]",
                LoginPassword = "123",                
                CurrentBalance = 0,
            };
        context.Users.AddOrUpdate(user);
    }
}

Answer 1

您可以先检查表是否为空：

if (!context.Users.Any())
{
    User user = new User()
    {
        UserId = 1,
        EmailAddress = "[e-mail]",
        LoginPassword = "123",
        CurrentBalance = 0
    };
    context.Users.AddOrUpdate(user);
}

或查看是否存在userId = 1的行：

if (context.Users.Where(a => UserId == 1).Count() == 0) { ...