从数据库获取唯一列结果的列表

Question

I've stumbled across this answer and it has helped me to generate a list of unique values exactly as I wanted, however, I don't want all of the results. Is there any way to filter the results within the select or another way to accomplish this?

I was thinking of something along the lines of this:

@results = MyModel.select("DISTINCT(columnForDistinction)", :myBoolean => false)

or

@results = MyModel.select("DISTINCT(columnForDistinction)", :someString => stringImLookingFor)

Currently, I'm not able to filter the results on the query, so I am iterating over the returned array and only listing the results that have that boolean set to false like so:

<% @results.each do |result| %>
  <% if !result.myBoolean %>
    #do stuff here
  <% end %>
<% end %>

and

<% @results.each do |result| %>
  <% if result.someString == stringImLookingFor %>
    #do stuff here
  <% end %>
<% end %>

Is there a better way to be doing this?

Answer 1

ActiveRecord query methods are chainable. You can call multiple and it will build them all into a query when you use the result. For conditions, you'll use where . Try something like:

@results = MyModel.select("DISTINCT(columnForDistinction)").where(:myBoolean => false)