Dapper simple mapping | 易学教程

问题

Table:

create table Documents 
   (Id int, 
    SomeText varchar(100), 
    CustomerId int, 
    CustomerName varchar(100)
   )

insert into Documents (Id, SomeText, CustomerId, CustomerName) 
   select 1, '1', 1, 'Name1' 
     union all
   select 2, '2', 2, 'Name2'

Classes:

public class Document
{
    public int Id { get; set; }
    public string SomeText { get; set; }
    public Customer { get; set; }
}

public class Customer
{
    public int Id { get; set; }
    public string Name { get; set; }
}

How can I get all Documents with their Customers with Dapper? This gives me all documents, but the customer is null (of course):

connection.Query<Document>("select Id, SomeText, CustomerId, CustomerName from Documents")...

EDIT - similar, but more advanced mapping question: Dapper intermediate mapping

回答1:

Example taken from dapper project page (see the Multi Mapping section):

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);

回答2:

var docs = connection.Query<Document, Customer, Document>(
    "select Id, SomeText, CustomerId as [Id], CustomerName as [Name] from Documents",
    (doc, cust) => { doc.Customer = cust; return doc; }).ToList();

来源：https://stackoverflow.com/questions/10170882/dapper-simple-mapping

标签

sql-server

orm

dapper