与PetaPoco相比，Dapper Map实现了一对多

Question

我刚刚从PetaPoco转到Dapper，我试图找到一个如何在Dapper中实现一对多关系的例子。在PetaPoco中，您可以执行以下操作。这很好，因为实现作者所需的所有逻辑都包含在一个类中。示例来自PetaPoco - Mapping One-to-Many and Many-to-One Relationships

public class AuthorPostRelator
{
    private author current;

    public author Map(author a, post p)
    {
        // Terminating call.  Since we can return null from this function
        // we need to be ready for PetaPoco to callback later with null
        // parameters
        if (a == null)
            return current;

        // Is this the same author as the current one we're processing
        if (current != null && current.id == a.id)
        {
            // Yes, just add this post to the current author's collection of posts
            current.posts.Add(p);

            // Return null to indicate we're not done with this author yet
            return null;
        }

        // This is a different author to the current one, or this is the 
        // first time through and we don't have an author yet

        // Save the current author
        var prev = current;

        // Setup the new current author
        current = a;
        current.posts = new List<post>();
        current.posts.Add(p);

        // Return the now populated previous author (or null if first time through)
        return prev;
    }
}


// use the AuthorPostRelator to materialize the returned Author objects.
var authors = db.Fetch<author, post, author>(new AuthorPostRelator().Map,
    "SELECT * FROM authors LEFT JOIN posts ON posts.author = authors.id ORDER BY posts.id");