How can I design this better? (Avoiding a switch statement with Object Oriented design)

Question

I know a little bit about Object Oriented design, but I\'m not sure how to go about using those principles in my code. Here\'s what I\'m working on:

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Answer 1

I would refactor to take advantage of an interface. I would probably make it something like:

public interface IQuery
{
    void Execute(Agency agency, Citation query);
}

public class OracleQuery : IQuery
{
    // Implementation
}

public class PickQuery : IQuery
{
    // Implementation
}

You could then change the Agency class to store an instance of an IQuery object rather than (or in addition to) the ClientDb object:

public class Agency
{
    public IQuery Query { get; set; }
}

And then in your initialization code (where you would normally set the ClientDb property), you could set the instance to the appropriate IQuery implementation:

agency.Query = new PickQuery();