[Ruby-DBI-devel] Re: Array-support for DBD::Pg ?

[Oliver M. B. <ol...@go...>]

On Thu, Feb 06, 2003 at 05:21:00PM +0100, "Oliver M. Bolzer" <ol...@go...> wrote...
 
> A really quick glance into DBD::Pg shows that the type conversion is
> done according to type_map and the type of a column according to pg_result.type
> 
> For example BIGINT[] gives type 1016, VARCHAR(255)[] gives 1015 as type
> on my system, but they are not contained in type_map, so they are converted
> to String....

I've done some more digging into PostgreSQL itself. 
After looking, how DBD::Pg assembles it's type_map and repeating the
queries myself, i tought that the pg_type table does not contain information
about Array types, but consulting the PostgreSQL documentation, it seems like
DBD::Pg's assembly of type_map is wrong.

Currently, type_map is assembled using typname and typelem from pg_type.
The typeid from  PGResult.type(index) comes from pg_attribute.atttypid, which
is an reference to pg_type.oid, not pg_type.typelem. 
pg_type.typdelem is the type of elements of an array. But because an
INT[] array always wraps INTs, the current code functions correctly.

Applying the following patch, the code still works the same way. 
Even the mysterious  1114 timestamp type could be folded into the case block.

IMHO, this is more correct and could be the base for Array support.
What do you think?

--- Pg.rb.orig  2003-02-06 18:32:10.000000000 +0100
+++ Pg.rb       2003-02-06 18:32:37.000000000 +0100
@@ -299,18 +299,18 @@
           @type_map = Hash.new
           @coerce = PgCoerce.new

-          res = @connection.exec("SELECT typname, typelem FROM pg_type")
+          res = @connection.exec("SELECT typname, oid FROM pg_type")

           res.result.each { |name, idstr|
             @type_map[idstr.to_i] =
             case name
-            when '_bool'                      then :as_bool
-            when '_int8', '_int4', '_int2'    then :as_int
-            when '_varchar'                   then :as_str
-            when '_float4','_float8'          then :as_float
-            when '_timestamp', '_timestamptz' then :as_timestamp
-            when '_date'                      then :as_date
-            when '_bytea'                     then :as_bytea
+            when 'bool'                      then :as_bool
+            when 'int8', 'int4', 'int2'    then :as_int
+            when 'varchar'                   then :as_str
+            when 'float4','float8'          then :as_float
+            when 'timestamp', 'timestamptz' then :as_timestamp
+            when 'date'                      then :as_date
+            when 'bytea'                     then :as_bytea
             else                                   :as_str
             end
           }




-- 
	Oliver M. Bolzer
	ol...@go...

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