NAME¶
SQL::Translator::Producer::TT::Base - TT (Template Toolkit) based Producer base
class.
SYNOPSIS¶
# Create a producer using a template in the __DATA__ section.
package SQL::Translator::Producer::Foo;
use base qw/SQL::Translator::Producer::TT::Base/;
# Convert produce call into a method call on our new class
sub produce { return __PACKAGE__->new( translator => shift )->run; };
# Configure the Template object.
sub tt_config { ( INTERPOLATE => 1 ); }
# Extra vars to add to the template
sub tt_vars { ( foo => "bar" ); }
# Put template in DATA section (or use file with ttfile producer arg)
__DATA__
Schema
Database: [% schema.database %]
Foo: $foo
...
DESCRIPTION¶
A base class producer designed to be sub-classed to create new TT based
producers cheaply - by simply giving the template to use and sprinkling in
some extra template variables and config.
You can find an introduction to this module in SQL::Translator::Manual.
The 1st thing the module does is convert the produce sub routine call we get
from SQL::Translator into a method call on an object, which we can then
sub-class. This is done with the following code which needs to appear in
all sub classes.
# Convert produce call into an object method call
sub produce { return __PACKAGE__->new( translator => shift )->run; };
See "PRODUCER OBJECT" below for details.
The upshot of this is we can make new template producers by sub classing this
base class, adding the above snippet and a template. The module also provides
a number of hooks into the templating process, see "SUB CLASS HOOKS"
for details.
See the SYNOPSIS above for an example of creating a simple producer using a
single template stored in the producers DATA section.
SUB CLASS HOOKS¶
Sub-classes can override these methods to control the templating by giving the
template source, adding variables and giving config to the Tempate object.
tt_config¶
sub tt_config { ( INTERPOLATE => 1 ); }
Return hash of Template config to add to that given to the Template
"new" method.
tt_schema¶
sub tt_schema { "foo.tt"; }
sub tt_schema { local $/ = undef; \<DATA>; }
The template to use, return a file name or a scalar ref of TT source, or an
IO::Handle. See Template for details, as the return from this is passed on to
it's "produce" method.
The default implimentation uses the producer arg "ttfile" as a
filename to read the template from. If the arg isn't there it will look for a
"__DATA__" section in the class, reading it as template source if
found. Returns undef if both these fail, causing the produce call to fail with
a 'no template!' error.
tt_vars¶
sub tt_vars { ( foo => "bar" ); }
Return hash of template vars to use in the template. Nothing added here by
default, but see tt_default_vars for the variables you get for free.
tt_default_vars¶
Return a hash-ref of the default vars given to the template. You wouldn't
normally over-ride this, just inherit the default implimentation, to get the
"translator" & "schema" variables, then over-ride
tt_vars to add your own.
The current default variables are:
- schema
- The schema to template.
- translator
- The SQL::Translator object.
pre_process_schema¶
WARNING: This method is Experimental so may change!
Called with the SQL::Translator::Schema object and should return one (it doesn't
have to be the same one) that will become the "schema" varibale used
in the template.
Gets called from tt_default_vars.
PRODUCER OBJECT¶
The rest of the methods in the class set up a sub-classable producer object. You
normally just inherit them.
new¶
my $tt_producer = TT::Base->new( translator => $translator );
Construct a new TT Producer object. Takes a single, named arg of the
SQL::Translator object running the translation. Dies if this is not given.
translator¶
Return the SQL::Translator object.
schema¶
Return the SQL::Translator::Schema we are translating. This is equivilent to
"$tt_producer->translator->schema".
run¶
Called to actually produce the output, calling the sub class hooks. Returns the
produced text.
args¶
Util wrapper method around "TT::Base->translator->producer_args"
for (mostley) readonly access to the producer args. How it works depends on
the number of arguments you give it and the context.
No args - Return hashref (the actual hash in Translator) or hash of args.
1 arg - Return value of the arg with the passed name.
2+ args - List of names. In list context returns values of the given arg
names, returns as a hashref in scalar context. Any names given
that don't exist in the args are returned as undef.
This is still a bit messy but is a handy way to access the producer args when
you use your own to drive the templating.
SEE ALSO¶
perl, SQL::Translator, Template.
TODO¶
- Add support for a sqlf template repository, set as an INCLUDE_PATH, so that
sub-classes can easily include file based templates using relative paths.
- Pass in template vars from the producer args and command line.
- Merge in TT::Table.
- Hooks to pre-process the schema and post-process the output.
AUTHOR¶
Mark Addison <grommit@users.sourceforge.net>.