> Do other drivers use driver-specific array types? I'm not sure about the driver-specific bit but I imagine that the driver designers will use a Java JDBC array type if the DB technology supports array columns or similar. I'm thinking of the newer breed of DB tech that is not tables, columns and rows for which JDBC APIs are becoming common.
> Do all of the JDBC drivers that support array columns return an object that will respond to to_ary? My understanding is, the driver returns an instance of java.sql.Array, via the `getArray(column)` Jruby will wrap the result in some kind of Ruby compatible proxy. That proxy will translate the `.array` call into `getArray()` and that call will return another JRuby proxy. If that proxy is an instance of `ArrayJavaProxy` then it has a `to_ary` method returning `JavaUtil.convertJavaArrayToRubyWithNesting(context, array)`. Without the call to `array` (as the postgres adapter does), AFAICT, `process_result_set` adds the proxy wrapped result of the `getArray(column)`. FWIW the activerecord-jdbc-adapter <https://github.com/jruby/activerecord-jdbc-adapter/blob/master/src/java/arjdbc/jdbc/RubyJdbcConnection.java#L2282> uses a arrayToRuby method on all jdbc for at least 7 years with the Postgres specific override removed in 28 Mar 2018 (array handling identical but different because "Method org.postgresql.jdbc4.Jdbc4Array.free() is not yet implemented"). Their approach is interesting as it recursive into the array but their code is in Java/JRuby so they avoid the proxy wrappers. HTH, Guy On Wednesday, August 14, 2019 at 3:02:18 PM UTC+1, Jeremy Evans wrote: > > On Wednesday, August 14, 2019 at 2:23:16 AM UTC-7, Guy Boertje wrote: >> >> Hi, >> >> I have a question regarding the generic type conversion for JDBC Array >> types. >> >> The java examples I've seen do a further getArray call on the object >> returned by resultset.getArray(column) >> >> java.sql.Array array = rs.getArray(columnIndex); >> if (array == null) { >> return true; >> } >> Object o = array.getArray(); >> >> It looks like the postgres jdbc adapter does the correct thing. >> >> # Return PostgreSQL array types as ruby Arrays instead of >> # JDBC PostgreSQL driver-specific array type. Only used if the >> # database does not have a conversion proc for the type. >> ARRAY_METHOD = Object.new >> def ARRAY_METHOD.call(r, i) >> if v = r.getArray(i) >> v.array.to_ary >> end >> end >> >> However, it looks like the generic jdbc adapter only calls >> getArray(column) >> >> %w'Object Array String Time Date Timestamp BigDecimal Blob Bytes >> Clob'.each do |meth| >> x = convertors[meth.to_sym] = Object.new >> class_eval("def x.call(r, i) r.get#{meth}(i) end", __FILE__, >> __LINE__) >> end >> >> Before I create an issue in github, I wanted to check if there is a >> reason for not making the postgres specific handling the default for all of >> JDBC. >> > > The documentation for the PostgreSQL method mentions that it is because > the JDBC PostgreSQL driver uses a driver-specific array type. Do other > drivers use driver-specific array types? Do all of the JDBC drivers that > support array columns return an object that will respond to to_ary? > > Thanks, > Jeremy > -- You received this message because you are subscribed to the Google Groups "sequel-talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to sequel-talk+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sequel-talk/48b7f533-1a18-478b-a1ff-0c61d40295a5%40googlegroups.com.
