I am new to Ruby on Rails and I have basic knowledge of mysql. I am using MySQL db. My question is -- how to check if a row is exists or not in a table. I have tried this code but it's not going straight to the else block, not the if block:
@tasks = User.find_by("user_name = ? AND password = ?", params[:user_name], params[:password]) if @tasks redirect_to action: 'index', status: 302 else redirect_to action: 'detail', status: 302 end If you want to find if a user with the given name and password exists using Ruby on Rails, then you can do this:
User.where(user_name: params[:user_name], password: params[:password]).exists? See the RailsGuides: Existence of Objects.
So this it the code that the original poster originally submitted:
User.find_by("user_name = ? AND password = ?", "#{params[:user_name]}", "#{params[:password]}") I removed the string interpolation because it was unnecessary
User.find_by("user_name = ? AND password = ?", params[:user_name], params[:password]) and apparently that fixed the problem. I'm not sure why it would make a difference though, the interpolated string should be the same value as the values in the params dictionary.
find_by in rails.You can use any of these solutions depending on your requirement.
Sol-1:
User.where(user_name: params[:user_name], password: params[:password]).exists? Sol-2:
User.find_by_user_name_and_password(params[:user_name], params[:password]) where returns an ActiveRecord::Relation (not an array, even though it behaves much like one), which is a collection of model objects. If nothing matches the conditions, it simply returns an empty relation.
find (and its related dynamic find_by_columnname methods) returns a single model object, or possibly a collection of model objects in an Array (not a Relation). If nothing is found, an ActiveRecord::RecordNotFound exception is raised.
So yes, if you only want and expect a single object, using find is easier, as otherwise you must call Model.where.first.
you can try it as well..
User.find_by_user_name_and_password(params[:user_name], params[:password])
find_by