使用 Dapper 删除列表<T>

Question

使用 Dapper 或 Dapper.SimpleCRUD，如何从 table 中删除列表。类似于：

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

但是当我尝试这样做时，我得到...

The member of type DataModel.MyTable cannot be used as a parameter value

WHERE 子句中传递的唯一选项是什么？

Answer 1

我没有看到任何 Dapper 方法可以实现您想要实现的目标。唯一的选项是两个单一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)

这两种多次删除都需要您传递条件或 where 子句。示例：

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

Answer 2

Dapper 不了解您的实体；它不像 Entity Framework。您需要自己执行一个SQL命令或一个存储过程。

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 3

不确定为什么选择以上答案。但是开箱即用的 Dapper 不支持列表功能。而不是在我的回答中重新创建轮子，请参阅：Delete rows from mysql server from a list of ID's C#...只是我的 2c。

Answer 4

简单方法：

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

使用 Dapper 删除列表<T>

Delete a List<T> using Dapper

.net

c#

dapper