Edit File: DBI::DBD::Metadata.3pm
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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" DBI::DBD::Metadata \- Generate the code and data for some DBI metadata methods .SH "SYNOPSIS" .IX Header "SYNOPSIS" The idea is to extract metadata information from a good quality \&\s-1ODBC\s0 driver and use it to generate code and data to use in your own \&\s-1DBI\s0 driver for the same database. .PP To generate code to support the get_info method: .PP .Vb 1 \& perl \-MDBI::DBD::Metadata \-e "write_getinfo_pm(\*(Aqdbi:ODBC:dsn\-name\*(Aq,\*(Aquser\*(Aq,\*(Aqpass\*(Aq,\*(AqDriver\*(Aq)" \& \& perl \-MDBI::DBD::Metadata \-e write_getinfo_pm dbi:ODBC:foo_db username password Driver .Ve .PP To generate code to support the type_info method: .PP .Vb 1 \& perl \-MDBI::DBD::Metadata \-e "write_typeinfo_pm(\*(Aqdbi:ODBC:dsn\-name\*(Aq,\*(Aquser\*(Aq,\*(Aqpass\*(Aq,\*(AqDriver\*(Aq)" \& \& perl \-MDBI::DBD::Metadata \-e write_typeinfo_pm dbi:ODBC:dsn\-name user pass Driver .Ve .PP Where \f(CW\*(C`dbi:ODBC:dsn\-name\*(C'\fR is the connection to use to extract the data, and \f(CW\*(C`Driver\*(C'\fR is the name of the driver you want the code generated for (the driver name gets embedded into the output in numerous places). .SH "Generating a GetInfo package for a driver" .IX Header "Generating a GetInfo package for a driver" The \f(CW\*(C`write_getinfo_pm\*(C'\fR in the DBI::DBD::Metadata module generates a DBD::Driver::GetInfo package on standard output. .PP This method generates a DBD::Driver::GetInfo package from the data source you specified in the parameter list or in the environment variable \s-1DBI_DSN\s0. DBD::Driver::GetInfo should help a \s-1DBD\s0 author implement the \s-1DBI\s0 \&\fIget_info()\fR method. Because you are just creating this package, it is very unlikely that DBD::Driver already provides a good implementation for \fIget_info()\fR. Thus you will probably connect via \s-1DBD::ODBC\s0. .PP Once you are sure that it is producing reasonably sane data, you should typically redirect the standard output to lib/DBD/Driver/GetInfo.pm, and then hand edit the result. Do not forget to update your Makefile.PL and \s-1MANIFEST\s0 to include this as an extra \s-1PM\s0 file that should be installed. .PP If you connect via \s-1DBD::ODBC\s0, you should use version 0.38 or greater; .PP Please take a critical look at the data returned! \&\s-1ODBC\s0 drivers vary dramatically in their quality. .PP The generator assumes that most values are static and places these values directly in the \f(CW%info\fR hash. A few examples show the use of \s-1CODE\s0 references and the implementation via subroutines. It is very likely that you will have to write additional subroutines for values depending on the session state or server version, e.g. \&\s-1SQL_DBMS_VER\s0. .PP A possible implementation of \fIDBD::Driver::db::get_info()\fR may look like: .PP .Vb 7 \& sub get_info { \& my($dbh, $info_type) = @_; \& require DBD::Driver::GetInfo; \& my $v = $DBD::Driver::GetInfo::info{int($info_type)}; \& $v = $v\->($dbh) if ref $v eq \*(AqCODE\*(Aq; \& return $v; \& } .Ve .PP Please replace Driver (or \*(L"<foo>\*(R") with the name of your driver. Note that this stub function is generated for you by write_getinfo_pm function, but you must manually transfer the code to Driver.pm. .SH "Generating a TypeInfo package for a driver" .IX Header "Generating a TypeInfo package for a driver" The \f(CW\*(C`write_typeinfo_pm\*(C'\fR function in the DBI::DBD::Metadata module generates on standard output the data needed for a driver's type_info_all method. It also provides default implementations of the type_info_all method for inclusion in the driver's main implementation file. .PP The driver parameter is the name of the driver for which the methods will be generated; for the sake of examples, this will be \*(L"Driver\*(R". Typically, the dsn parameter will be of the form \*(L"dbi:ODBC:odbc_dsn\*(R", where the odbc_dsn is a \s-1DSN\s0 for one of the driver's databases. The user and pass parameters are the other optional connection parameters that will be provided to the \s-1DBI\s0 connect method. .PP Once you are sure that it is producing reasonably sane data, you should typically redirect the standard output to lib/DBD/Driver/TypeInfo.pm, and then hand edit the result if necessary. Do not forget to update your Makefile.PL and \s-1MANIFEST\s0 to include this as an extra \s-1PM\s0 file that should be installed. .PP Please take a critical look at the data returned! \&\s-1ODBC\s0 drivers vary dramatically in their quality. .PP The generator assumes that all the values are static and places these values directly in the \f(CW%info\fR hash. .PP A possible implementation of \fIDBD::Driver::type_info_all()\fR may look like: .PP .Vb 5 \& sub type_info_all { \& my ($dbh) = @_; \& require DBD::Driver::TypeInfo; \& return [ @$DBD::Driver::TypeInfo::type_info_all ]; \& } .Ve .PP Please replace Driver (or \*(L"<foo>\*(R") with the name of your driver. Note that this stub function is generated for you by the write_typeinfo_pm function, but you must manually transfer the code to Driver.pm. .SH "AUTHORS" .IX Header "AUTHORS" Jonathan Leffler <jleffler@us.ibm.com> (previously <jleffler@informix.com>), Jochen Wiedmann <joe@ispsoft.de>, Steffen Goeldner <sgoeldner@cpan.org>, and Tim Bunce <dbi\-users@perl.org>.
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