使用Dapper C#填充列表对象 [英] Fill list object using dapper c#

问题描述

我的数据库中有两个这样的表:

I have two table in my database like this:

我有这个课:

   class Ean
   {
        public string Code{ get; set; }
   }

   class Article
   {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<Ean> BarCode { get; set; }
   }

List<Article> arts = new List<Article>();

我创建文章列表，并使用 dapper 进行查询.我想用文章名称来填充此列表，还要用相关的 ean 文章列表来填充.我尝试执行此查询:

I create a list of article , and with a query using dapper. I would like to fill this list with the name of the article but also with a list of related ean Article. I try to do this query:

SELECT ART.ID AS ID, ART.NAME AS NAME,EAN.EAN AS BARCODE
FROM ART,EAN
WHERE ART.ID = EAN.ID_ART;

和c#..

arts = conn.Query<Article>(query, null, transaction).ToList();

但不起作用.我该怎么办?谢谢.欢迎任何建议.

but don't work. How i can do? Thank's.. Any suggestion is welcome.

推荐答案

看看Dapper的多-映射功能.

Take a look at Dapper's Multi-Mapping feature.

Dapper允许您将单行映射到多个对象.这是一个 如果您想要避免不必要的查询和急于加载的关键功能 关联.

Dapper allows you to map a single row to multiple objects. This is a key feature if you want to avoid extraneous querying and eager load associations.

示例:

var sql = 
@"select * from #Posts p 
left join #Users u on u.Id = p.OwnerId 
Order by p.Id";

var data = connection.Query<Post, User, Post>(sql, (post, user) => { post.Owner = user; return post;});
var post = data.First();

post.Content.IsEqualTo("Sams Post1");
post.Id.IsEqualTo(1);
post.Owner.Name.IsEqualTo("Sam");
post.Owner.Id.IsEqualTo(99);

重要说明Dapper假设您的ID列名为"Id"或"id"， 如果您的主键不一样，或者您想分割范围 在"Id"以外的其他位置排，请使用可选的"splitOn"参数.

Important note Dapper assumes your Id columns are named "Id" or "id", if your primary key is different or you would like to split the wide row at point other than "Id", use the optional 'splitOn' parameter.

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