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Using Dapper Multi-Mapping to Resolve the N+1 Problem

Using Dapper Multi-Mapping to Resolve the N+1 Problem

Learn to use Dapper multi-mapping to resolve the N+1 problem.

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Wouldn't it be great if we could get the questions and answers in a single database query and then map this data to the hierarchical structure that we require in our data repository? Well, this is exactly what we can do with a feature called multi-mapping in Dapper. Let's look at how we can use this. Follow these steps:

  1. In the data repository, let's change the implementation of the GetQuestionsWithAnswers method to call a single stored procedure:

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public IEnumerable<QuestionGetManyResponse>
  GetQuestionsWithAnswers()
{
  using (var connection = new
   SqlConnection(_connectionString))
  {
    connection.Open();
    return connection.Query<QuestionGetManyResponse>(
        "EXEC dbo.Question_GetMany_WithAnswers");
  }
}

This is a good start but the ...