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Re^4: Using DBIx::Class::Schema::Loader to determine constraints

by jds17 (Pilgrim)
on Oct 31, 2012 at 23:53 UTC ( #1001762=note: print w/ replies, xml ) Need Help??


in reply to Re^3: Using DBIx::Class::Schema::Loader to determine constraints
in thread Using DBIx::Class::Schema::Loader to determine constraints

Thank you for the clarification! SQL::Translator looks really impressive, but I fear that it is nontrivial to create the dumps for each DBMS (db user rights?) and that it may also not be stable enough to use SQL::Translator on those dumps for my purpose.

Recently, I have put a module on CPAN (DBIx::Table::TestDataGenerator). Currently, some methods related to finding out database metadata related to constraints have been abstracted into a role and for each DBMS I want to support the plan was to write a class impersonating that role. This gives me a good control over how the metadata is queried and I can even handle relevant DBMS version differences.

I would not want the code to crash because a dump cannot be created or read. On the other hand I don't want to reinvent the wheel and I acknowledge that it does not look too elegant handling each DBMS separately (although one learns a lot while doing this), maybe you can still convince me that using SQL::Translator is better.


Comment on Re^4: Using DBIx::Class::Schema::Loader to determine constraints
Re^5: Using DBIx::Class::Schema::Loader to determine constraints
by pokki (Scribe) on Nov 01, 2012 at 09:45 UTC

    From what I can see, you're currently using the same kind of tricks (table_info) as the SQL::Translator::Parser::DBI::$Driver modules. These have also worked for me in the past. Basically instead of passing them DDL in a big string, you give them a DSN, username and password (an open database handle works too). Then SQL::Translator::Parser::DBI selects the appropriate $Driver, which goes and fetches the metadata directly from the database.

    If you have enough permissions to use table_info, you have enough permissions to use the DBI parsers.

    The doc for the DBI parser says that Oracle is not supported and Pg support is experimental, but if you look at the module list for the distribution there *is* a DBI::Oracle class, so the doc is probably out of date. I'd say, install SQL::Translator, play around on real databases, see if it fits your needs.

      I have just tried out what you wrote in your last post and I like the idea of doing it this way. To be more specific what I tried out was:

      use strict; use warnings; use DBI; use SQL::Translator; my $dbh = DBI->connect( 'dbi:Pg:dbname=playground', 'postgres', '***** +**' ); my $translator = SQL::Translator->new( parser => 'DBI', parser_args => { dbh => $dbh, } ); $translator->translate(); my $schema = $translator->schema; for my $rsrc_name ( $schema->get_tables() ) { my $rsrc = $schema->get_table($rsrc_name); ... } ...

      The Pg support indeed is not complete, I had tested with a table having a two-column primary key and the parse() method of SQL::Translator::Parser::DBI::PostgreSQL failed (currently it only works on one-column pkeys).

      I have posted a bug report and a proposal for a patch on rt.cpan.org (see here). The bug was easy to fix. So one possibility would be to continue with my database-wise handling and the other to help out finding and maybe help fixing remaining bugs in the SQL::Translator::Parser::DBI::XXXXX modules.

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