Splitting row into several nested objects

Question

Splitting row into several nested objects

dapper

Question

I've got the following query:

select id, name, email, supervisor, createdBy, createdAt, changedBy, changedAt from XXX

Now, I'd like to map each row into something that looks like this:

public class Organisation{
  public int Id{get; set; }
  public string Name{get; set; }
  public ContactInfo Contact{get;set;}
  public Action CreatedBy{get;set;}
  public Action ChangedBy{get;set;}
}
public class ContactInfo{
  public string Name{get;set;}
  public string Email{get;set;}
}
public class Action{
  public string Username{get;set;}
  public DateTime At{get;set;}
}

I've seen some examples that show how to partition the info, but it seems like will not work in this example. Can it be done or should I map my query into a helper object which will then be mapped into these classes?

Thanks.

Luis

Luis Abreu

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Void Ray · Accepted Answer · 12/14/2017 9:27:58 PM

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.

You can read about it more here

Below is an example:

[Test]
public void Test_Multi()
{
    using (var conn = new SqlConnection(@"Data Source=.\sqlexpress;Integrated Security=true; Initial Catalog=foo"))
    {
        var result = conn.Query<Organisation, ContactInfo, Action, Action, Organisation>(
            @"select Id = 100, Name = 'Foo', 
                Name = 'Contact Name', Email = 'contact@foo.com', 
                Username = 'The Creator', At = '12/25/2017', 
                Username = 'The Modifier', At = '12/26/2017' ",
            (org, contact, cretedBy, changedBy) =>
            {
                org.Contact = contact;
                org.CreatedBy = cretedBy;
                org.ChangedBy = changedBy;

                return org;
            }, splitOn: "Id, Name, Username, Username").First();

        Assert.That(result.Id, Is.EqualTo(100));
        Assert.That(result.Contact.Email, Is.EqualTo("contact@foo.com"));
        Assert.That(result.CreatedBy.Username, Is.EqualTo("The Creator"));
        Assert.That(result.ChangedBy.Username, Is.EqualTo("The Modifier"));

    }
}

Splitting row into several nested objects

Question

Fastest Dapper Plus Extensions

Accepted Answer

Performance

Expression Evaluator