Question

使用Dapper或Dapper.SimpleCRUD，如何从表中删除列表。类似的东西：

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

但是当我尝试的时候，我得到......

DataModel.MyTable类型的成员不能用作参数值

传递WHERE子句的唯一选择是什么？

Answer 1

Dapper并不了解你的实体;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Execute a Command multiple times

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 2

简便方法：

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

Answer 3

我没有看到任何你想要实现的Dapper方法。唯一的选择是两个单个删除和两个多个删除。

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)

多次删除都要求您传递条件或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});

Answer 4

不确定选择上述答案的原因。但开箱即用的Dapper不支持列表功能。而不是在我的答案中重新创建轮子，请参阅：Delete rows from mysql server from a list of ID's C# ...只是我的2c。

使用Dapper删除List <t>

4 个答案: