使用 Dapper 将包含表示列表的字符串的列映射到 List<> 对象

Question

我有以下型号：

public class Model {
   public string Name { get; set; }
   public List<int> Numbers { get; set; }
}

并且 SQL 查询 returns 以下数据集包含两个 nvarchar 列：

Name	Numbers
foo	1,2,3,4
bar	4,17

有没有一种简单的方法可以使用 Dapper 将查询结果自动分配给 List<Model>？

我知道我可以使用多重映射并在 C# 代码中自行拆分，但我宁愿获得更简单的解决方案。

Answer 1

我不确定你是否可以这样称呼 "simpler"，但可以这样称呼：

public class Result
{
    public string Name { get; set; }
    public List<int> Numbers { get; set; }
}
public class DapperTests
{
    [Test]
    public void Test()
    {
        var conn = new SqlConnection(@"Data Source=.\sqlexpress; Integrated Security=true; Initial Catalog=mydb");

        conn.Open();

        var result = conn.Query<string, string, Result>(
                    "select Name = 'Foo', Numbers = '1,2,3' union all select Name = 'Bar', Numbers = '4,5,6'", (a, b) => new Result
                    {
                        Name = a,
                        Numbers = b.Split(',').Select(Int32.Parse).ToList()
                    }, splitOn: "*").ToList();

        Assert.That(result.Count, Is.EqualTo(2));
        Assert.That(result.FirstOrDefault(x => x.Name == "Foo").Numbers.Count, Is.GreaterThan(0));
        Assert.That(result.FirstOrDefault(x => x.Name == "Bar").Numbers.Count, Is.GreaterThan(0));
    }
}

Answer 2

多映射的替代选项...非常难看

public class Result
{
    public string Name { get; set; }
    public List<int> NumberList { get; set; }
    public string Numbers { set { NumberList = value.Split(',').Select(Int32.Parse).ToList(); } }
}

public class DapperTests
{
    [Test]
    public void Test()
    {
        var conn = new SqlConnection(@"Data Source=.\sqlexpress; Integrated Security=true; Initial Catalog=mydb");

        conn.Open();

        var sql = @"
            select Name = 'Foo', Numbers = '1,2,3';
            select Name = 'Bar', Numbers = '4,5,6';";

        var expectedResults = 2;

        var results = new List<Result>();
        using (var multi = conn.QueryMultiple(sql))
        {
            for (int i = 0; i < expectedResults; i++)
            {
                results.Add(multi.Read<Result>().Single());
            }
        }

        Assert.That(results.Count, Is.EqualTo(2));

        Assert.That(results.FirstOrDefault(x => x.Name == "Foo").NumberList.Count, Is.GreaterThan(0));
        Assert.That(results.FirstOrDefault(x => x.Name == "Bar").NumberList.Count, Is.GreaterThan(0));
    }
}

使用 Dapper 将包含表示列表的字符串的列映射到 List<> 对象

Map a column with string representing a list to a List<> object using Dapper

sql-server

split

dapper