ActiveRecord :select is messing with my data types

So I have this very simple snippet.

Topic.all(:select => 'count(*) as cnt')[0].cnt   # behaves the same on all models
"500"  # What, a string? 

It seems that for some reason ActiveRecord is coercing the count to a string. In fact, I notice it coerces everything in the select list missing from the original object to a string.

Why does this happen?

What is a monkey patch to fix this so it works as expected?

Please: I do not want to use Topic.count, I have some tricky grouping and selecting I need to do.

FYI using ActiveRecord 2.3.5

Proof that the info is in the raw connecti开发者_如何学Pythonon:

ree-1.8.7-2009.10 > r = ActiveRecord::Base::connection.raw_connection.query(
     "select 1").fetch_field.type == Mysql::Field::TYPE_LONGLONG
 => true
ree-1.8.7-2009.10 > r = ActiveRecord::Base::connection.raw_connection.query(
    "select 'a'").fetch_field.type == Mysql::Field::TYPE_VAR_STRING
 => true

And when using the Stmt APIs you get stuff with the right types back automatically

ree-1.8.7-2009.10 > s = ActiveRecord::Base::connection.raw_connection.stmt_init
 => #<Mysql::Stmt:0xbd083dc>
ree-1.8.7-2009.10 > s.prepare("select 1, 'hello'")
 => #<Mysql::Stmt:0xbd083dc>
ree-1.8.7-2009.10 > s.execute
 => #<Mysql::Stmt:0xbd083dc>
ree-1.8.7-2009.10 > s.fetch
 => [1, "hello"]
ree-1.8.7-2009.10 >

But ... the Active Record MySql Adapter uses the query API that returns strings.

ree-1.8.7-2009.10 > cnn.query("select 1,2,3 union all select 1,2,3").each{|r| p r}
["1", "2", "3"]
["1", "2", "3"]

It might actually be because there is no easy way to assume what the value is, so String is 'safe'. Anything in a select that does not map to a column can't be introspected for a type.

The problem is MySQL. When MySQL returns the result set, the result set does not have information as to what types are the columns. ActiveRecord can only do the best it can: treat everything as a String.

ActiveRecord can treat columns coming back from a "normal" query (SELECT id FROM topics) as the correct type because ActiveRecord asked the DB for the types of the columns.