Mysql2 response does not work with method collect in Ruby

Question

I am using mysql2 in my ruby script. using this to test API responses against the mysql DB

this is a snippet of my script

test_job_by_id_5
 id = $data["jobs"]["id"][i] # example 5
 job = JobServices.job_by_id(id)
 response = @@con.query("select * from jobs where id = #{id}") #select * from jobs where id =5
 rs=response.collect #this fails
 assert_match(job[0]['title'],rs[0]['title'],"The title values are equal for #{$data["jobs"]["id"][i]}")
end

So when i use this with ruby 1.8.7 (2011-06-30 patchlevel 352) [i686-darwin10] it works like a charm

but when i use ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-linux] it does not work i get this error

NoMethodError: undefined method '[]' for 
#<Enumerator: #<Mysql2::Result:0x00000012d19f18>:collect>

Can some one please help me fix this?

Answer 1

When you call collect on an Enumerable (which Mysql2::Result is), you get an Enumerator instance back. Enumerators don't implement the array access operator so you can't say enumerator[0] and get anything useful to happen; however, Enumerator does include Enumerable so they do respond to first so you probably want to do this:

rs  = response.collect
row = rs.first
assert_match(job[0]['title'], row['title'], "The title values are equal for #{$data["jobs"]["id"][i]}")

Or just skip the Enumerator entirely and call first on the response:

row = response.first
assert_match(job[0]['title'], row['title'], "The title values are equal for #{$data["jobs"]["id"][i]}")

or even this:

row = @@con.query("select * from jobs where id = #{id}").first
assert_match(job[0]['title'], row['title'], "The title values are equal for #{$data["jobs"]["id"][i]}")

Keep in mind that row.nil? will be true if your query doesn't find anything so you might want to take that into account if you don't want an exception.