How to select where ID in Array Rails ActiveRecord without exception
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10-07-2019 - |
Question
When I have array of ids, like
ids = [2,3,5]
and I perform
Comment.find(ids)
everything works fine. But when there is id that doesn't exist, I get an exception. This occurs generaly when I get list of IDs that match some filter and than I do something like
current_user.comments.find(ids)
This time I may have a valid comment ID, which however does not belong to given User, so it is not found and I get an exception.
I've tried find(:all, ids)
, but it returns all of the records.
The only way I can do it now is
current_user.comments.select { |c| ids.include?(c.id) }
But that seems to me like super inefficient solution.
Is there better way to select ID in Array without getting exception on non-existing record?
Solution
If it is just avoiding the exception you are worried about, the "find_all_by.." family of functions works without throwing exceptions.
Comment.find_all_by_id([2, 3, 5])
will work even if some of the ids don't exist. This works in the
user.comments.find_all_by_id(potentially_nonexistent_ids)
case as well.
Update: Rails 4
Comment.where(id: [2, 3, 5])
OTHER TIPS
Update: This answer is more relevant for Rails 4.x
Do this:
current_user.comments.where(:id=>[123,"456","Michael Jackson"])
The stronger side of this approach is that it returns a Relation
object, to which you can join more .where
clauses, .limit
clauses, etc., which is very helpful. It also allows non-existent IDs without throwing exceptions.
The newer Ruby syntax would be:
current_user.comments.where(id: [123, "456", "Michael Jackson"])
If you need more control (perhaps you need to state the table name) you can also do the following:
Model.joins(:another_model_table_name)
.where('another_model_table_name.id IN (?)', your_id_array)
Now .find and .find_by_id methods are deprecated in rails 4. So instead we can use below:
Comment.where(id: [2, 3, 5])
It will work even if some of the ids don't exist. This works in the
user.comments.where(id: avoided_ids_array)
Also for excluding ID's
Comment.where.not(id: [2, 3, 5])
To avoid exceptions killing your app you should catch those exceptions and treat them the way you wish, defining the behavior for you app on those situations where the id is not found.
begin
current_user.comments.find(ids)
rescue
#do something in case of exception found
end
Here's more info on exceptions in ruby.
You can also use it in named_scope if You want to put there others conditions
for example include some other model:
named_scope 'get_by_ids', lambda { |ids| { :include => [:comments], :conditions => ["comments.id IN (?)", ids] } }