rails, using the where method to search on complex criteria

If you want to list them, just do so below, but it is too simple to be complicated.

def index
  @samples = Sample.all
end

For more, complex things, use query methods.

Frequently used ones.

Methods	Summary
where	filtering by condition
not	expresses a negative conditional expression
order	sorting
reorder	override sort expression
select	specify columns
distinct	get records with no duplicates
limit	specify records to be extracted
offset	specify the number of records to start extracting, used with limit
group	group the results by a specific key
having	GROUP BY with additional constraints
joins	with other models
includes	Get all related models at once
readonly	make retrieved objects read-only
none	retrieve an empty result set

Use with the where method to make sure only what you create is displayed.

def index
  @samples = Sample.all
end

If you simply use ALL, you will see not only your own, but also those of other users, so you can use the where method to make sure that only yours are displayed. The example below means to filter only those that are identical to the current user and the user who created the SAMPLE.

def index
  @samples = Sample.where(user_id: current_user.id)
end