Reworked Manual::Intro to use load_namecpaces

[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / Manual / Troubleshooting.pod

=head1 NAME

DBIx::Class::Manual::Troubleshooting - Got a problem? Shoot it.

=head2  "Can't locate storage blabla"

You're trying to make a query on a non-connected schema. Make sure you got
the current resultset from $schema->resultset('Artist') on a schema object
you got back from connect().

=head2 Tracing SQL

The C<DBIC_TRACE> environment variable controls
SQL tracing, so to see what is happening try

  export DBIC_TRACE=1

Alternatively use the C<< storage->debug >> class method:-

  $class->storage->debug(1);

To send the output somewhere else set debugfh:-

  $class->storage->debugfh(IO::File->new('/tmp/trace.out', 'w');

Alternatively you can do this with the environment variable too:-

  export DBIC_TRACE="1=/tmp/trace.out"

=head2 Can't locate method result_source_instance

For some reason the table class in question didn't load fully, so the
ResultSource object for it hasn't been created. Debug this class in
isolation, then try loading the full schema again.

=head2 Can't get last insert ID under Postgres with serial primary keys

Older L<DBI> and L<DBD::Pg> versions do not handle C<last_insert_id>
correctly, causing code that uses auto-incrementing primary key
columns to fail with a message such as:

  Can't get last insert id at /.../DBIx/Class/Row.pm line 95

In particular the RHEL 4 and FC3 Linux distributions both ship with
combinations of L<DBI> and L<DBD::Pg> modules that do not work
correctly.

L<DBI> version 1.50 and L<DBD::Pg> 1.43 are known to work.

=head2 ... Can't locate object method "source_name" via package ...

There's likely a syntax error in the table class referred to elsewhere
in this error message.  In particular make sure that the package
declaration is correct, so for a schema C< MySchema > you need to
specify a fully qualified namespace: C< package MySchema::MyTable; >
for example.

=head2 syntax error at or near "<something>" ...

This can happen if you have a relation whose name is a word reserved by your
database, e.g. "user":

  package My::Schema::User;
  ...
  __PACKAGE__->table('users');
  __PACKAGE__->add_columns(qw/ id name /);
  __PACKAGE__->set_primary_key('id');
  ...
  1;

  package My::Schema::ACL;
  ...
  __PACKAGE__->table('acl');
  __PACKAGE__->add_columns(qw/ user_id /);
  __PACKAGE__->belongs_to( 'user' => 'My::Schema::User', 'user_id' );
  ...
  1;

  $schema->resultset('ACL')->search(
    {},
    {
      join => [qw/ user /],
      '+select' => [ 'user.name' ]
    }
  );

The SQL generated would resemble something like:

  SELECT me.user_id, user.name FROM acl me
  JOIN users user ON me.user_id = user.id

If, as is likely, your database treats "user" as a reserved word, you'd end
up with the following errors:

1) syntax error at or near "." - due to "user.name" in the SELECT clause

2) syntax error at or near "user" - due to "user" in the JOIN clause

The solution is to enable quoting - see
L<DBIx::Class::Manual::Cookbook/Setting_quoting_for_the_generated_SQL> for
details.

Note that quoting may lead to problems with C<order_by> clauses, see
L<... column "foo DESC" does not exist ...> for info on avoiding those.

=head2 column "foo DESC" does not exist ...

This can happen if you've turned on quoting and then done something like
this:

  $rs->search( {}, { order_by => [ 'name DESC' ] } );

This results in SQL like this:

  ... ORDER BY "name DESC"

The solution is to pass your order_by items as scalar references to avoid
quoting:

  $rs->search( {}, { order_by => [ \'name DESC' ] } );

Now you'll get SQL like this:

  ... ORDER BY name DESC

=cut