Sql Query on Param in ruby on rails

Ruby provide some use full method like singularize , classify, constantize by using this method we

are fetch data by sql query on params element.

suppose i fetch data by params[:id] and params[:controller] 

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@result = params[:controller].singularize.classify.constantize.where(id: params[:id]).first

This working on every controller its act like model for every controller like suppose.

if params[:controller] => ProjectsController then singularize is convert this in singular and constantize convert  string to Project.