使用Dapper删除List <T>

Question

使用Dapper或Dapper.SimpleCRUD，如何从表中删除列表。就像是：

    public static void DeleteList<T>(List<T> listToDelete)
    {
        using (var connection = OpenConnection())
        {
            connection.Delete<T>(listToDelete);
        }
    }

但是当我尝试时，我得到...

类型DataModel.MyTable的成员不能用作参数值

是传递WHERE子句的唯一选择吗？

Answer 1

简单的方法：

public void BulkDelete(IEnumerable<int> idList)
    {
        using (var connection = GetNewConnection())
        {
            connection.Execute("Delete FROM MY_TABLE WHERE Id in @idList", new { idList });
        }
    }

Answer 2

Dapper不了解您的实体；它不像实体框架。您需要自己执行SQL命令或存储过程。

public static void DeleteList(List<int> idToDelete)
{
    using (IDbConnection conn = new SqlConnection(connString))
    {
        conn.Open();
        foreach (int id in idToDelete)
        {
            conn.Execute(@"DELETE FROM [User] WHERE Id = @Id", new {Id = id});
        }
    }
}

或多次执行命令

public static void DeleteList(List<int> idToDelete)
{
    using (IDbConnection conn = new SqlConnection(connString))
    {
        conn.Open();
        conn.Execute(@"DELETE FROM [User] WHERE Id = @Id",
            idToDelete.Select(x => new { Id = x }).ToArray());
    }
}

Answer 3

我没有看到任何适合您想要实现的目标的 Dapper 方法。唯一的选项是两个单一删除和两个多重删除。

public static int Delete<T>(this IDbConnection connection, int Id)

public static int Delete<T>(this IDbConnection connection, T entityToDelete)

public static int DeleteList<T>(this IDbConnection connection, object whereConditions, IDbTransaction transaction = null, int? commandTimeout = null)

public static int DeleteList<T>(this IDbConnection connection, string conditions, object parameters = null, IDbTransaction transaction = null, int? commandTimeout = null)

两种多重删除都需要您传递条件或 where 子句。例子：

connection.DeleteList<User>(new { Age = 10 });
connection.DeleteList<User>("Where age > 20");
connection.DeleteList<User>("Where age > @Age", new {Age = 20});