c# - Using Dapper to map more than 5 types

Question

I am currently building a SELECT query that joins 12 tables together. I've been using Dapper for all my other queries and it works great. Problem is, the generic methods only have to five generic parameters.

I've previously modified the code to support up to 6 for another query, but now I really don't think I should be hacking 6 more levels of generics.

Is there a way to pass dapper an array of types, and it returns the results as an array of objects, which I can cast manually if I have to?

I also might be approaching the problem the wrong way! Any help will be appreciated!

Answer 1

In a project I worked on I saw something like this to get more than 7 types mapped. We used Dapper 1.38:

connection.Query<TypeOfYourResult>
(
   queryString,
   new[]
   {
      typeof(TypeOfArgument1),
      typeof(TypeOfArgument2),
      ...,
      typeof(TypeOfArgumentN)
   },
   objects =>
   {
      TypeOfArgument1 arg1 = objects[0] as TypeOfArgument1;
      TypeOfArgument2 arg2 = objects[1] as TypeOfArgument2;
      ...
      TypeOfArgumentN argN = objects[N] as TypeOfArgumentN;

     // do your processing here, e.g. arg1.SomeField = arg2, etc.
     // also initialize your result

     var result = new TypeOfYourResult(...)

     return result;
   },
   parameters,
   splitOn: "arg1_ID,arg2_ID, ... ,argN_ID"
);

The queryString is self-explanatory. The splitOn parameter says how Dapper should split the columns from the SELECT statement so that everything can be mapped properly to the objects, you can read about it here.