Question

我正在尝试做更好的数据整合性能＆amp;备份统一，允许单独的项目在一个数据库中使用单独的模式。

但我陷入了困境，实体框架执行两个问题 - 数据库创建然后创建表对象 - 在其一个Database.Create（）函数中。

有没有办法在没有数据库重新创建的情况下获取表对象创建活动？我希望每个项目共享一个数据库，但具有明确定义的模式所有权。

此代码的主要项目是首先使用代码，因此我们的团队可以同时处理模型的各个部分。此外，该项目不使用迁移，因为我们已在所有部署中使用智能默认设置进行生产。

以下是我到目前为止创建的代码。 “// TODO：”部分是我被卡住的地方。

此致伊恩

namespace app1.Models
{
    using System;
    using System.Data.Entity;
    using System.Data.Entity.Infrastructure.Interception;
    using System.Diagnostics;
    using System.Linq;

    public class Model1 : DbContext
    {
        public Model1()
            : base("name=Model1")
        {
            // Log database activity
            this.Database.Log = DebugWrite;
        }
        private void DebugWrite(string s) { Debug.Write(s); } // Avoiding Compiler Error CS1618

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.HasDefaultSchema("b1");
            base.OnModelCreating(modelBuilder);
        }

        //public virtual DbSet<blog1> blog1 { get; set; }
        //public virtual DbSet<common> common { get; set; }
    }


    public class DbB1SchemaInitializer : IDatabaseInitializer<Model1>
    {
        public void InitializeDatabase(Model1 context)
        {
            context.Database.Log = DebugWrite;

            if (context.Database.Exists())
            {
                if (!context.Database.CompatibleWithModel(true))
                {
                    context.Database.Delete();  // TODO: remove this and make delete the schema and its objects
                    context.Database.Create();  // TODO: remove this and make delete the schema and its objects

                    // Reinstall, create schema and application role.
                    context.Database.ExecuteSqlCommand("CREATE SCHEMA b1");
                    context.Database.ExecuteSqlCommand("CREATE APPLICATION ROLE blog1 WITH PASSWORD = 'Pwd0123456', DEFAULT_SCHEMA = b1");
                    context.Database.ExecuteSqlCommand("GRANT SELECT, UPDATE, INSERT, DELETE, EXECUTE on SCHEMA::b1 to blog1");
                }
            }
            else
            {
                // Fresh install, create the database, schema and application role.
                context.Database.Create(); // Create will make database and make the tables.
                context.Database.ExecuteSqlCommand("CREATE APPLICATION ROLE blog1 WITH PASSWORD = 'Pwd0123456', DEFAULT_SCHEMA = b1");
                context.Database.ExecuteSqlCommand("GRANT SELECT, UPDATE, INSERT, DELETE, EXECUTE on SCHEMA::b1 to blog1");
            }

            // Do database connection interception so database application security is used rather than database user security from this point on.
            //DbInterception.Add(new EFDBConnectionApplicationRoleInterception("blog1", "Pwd0123456"));
        }
        private void DebugWrite(string s) { Debug.Write(s); } // Avoiding Compiler Error CS1618
    }
}

Answer 1

我不清楚为什么你要这样做，但如果重新构建架构，这可能会对你有所帮助：

var command = "IF (NOT EXISTS (SELECT * FROM sys.schemas WHERE name = N'b1')) " +
            "BEGIN" +
            "  EXEC ('CREATE SCHEMA B1');" +
            "  EXEC ('CREATE APPLICATION ROLE blog1 WITH PASSWORD = ''Pwd0123456'', DEFAULT_SCHEMA = b1');" +
            "  EXEC ('GRANT SELECT, UPDATE, INSERT, DELETE, EXECUTE on SCHEMA::b1 to blog1');" +
            "END";
context.Database.ExecuteSqlCommand(command);

Answer 2

好的，我已经找到了解决方案。我发现命令拦截器主题然后实现了一个来改变＆＃34; CREATE DATABASE＆＃34;进入＆＃34; SELECT 0＆＃34;言。

                // context.Database.Create();  // TODO: remove this and make delete the schema and its objects
                var HandleNoCreateDatabase = new HandleNoCreateDatabase();
                DbInterception.Add(HandleNoCreateDatabase);
                context.Database.Create();
                DbInterception.Remove(HandleNoCreateDatabase);

...

public class HandleNoCreateDatabase : IDbCommandInterceptor
{

    public void NonQueryExecuting(
        DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        LogIfNonAsync(command, interceptionContext);
    }

    public void NonQueryExecuted(
        DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        LogIfError(command, interceptionContext);
    }

    public void ReaderExecuting(
        DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        LogIfNonAsync(command, interceptionContext);
    }

    public void ReaderExecuted(
        DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        LogIfError(command, interceptionContext);
    }

    public void ScalarExecuting(
        DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        LogIfNonAsync(command, interceptionContext);
    }

    public void ScalarExecuted(
        DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        LogIfError(command, interceptionContext);
    }

    private void LogIfNonAsync<TResult>(
        DbCommand command, DbCommandInterceptionContext<TResult> interceptionContext)
    {
        if (!interceptionContext.IsAsync)
        {
            Debug.Print("Non-async command used: {0}", command.CommandText);

            // If EF is checking for database existance, tell it that it does not exist
            if (command.CommandText.ToLower().Contains("select count(*) from sys.databases where [name]="))
            {
                command.CommandText = "SELECT 0";
            }

            // If EF is creating the database, disable the create request
            if (command.CommandText.ToLower().Contains("create database"))
            {
                command.CommandText = "SELECT 0";
            }
        }
    }

    private void LogIfError<TResult>(
        DbCommand command, DbCommandInterceptionContext<TResult> interceptionContext)
    {
        if (interceptionContext.Exception != null)
        {
            Debug.Print("Command {0} failed with exception {1}",
                command.CommandText, interceptionContext.Exception);
        }
    }
}

有关详细信息，请参阅 MSDN - Logging and Intercepting Database Operations (EF6 Onwards)

Github - julielerman/EF6Interceptors

注意，我认为拦截器应该用于单元测试，因此我不建议将其作为问题类型的首选解决方案。

实体框架代码首先 - 让它在没有删除数据库的情况下执行“CREATE SCHEMA”？

2 个答案: