DS::Transformer - receives, transforms and passes on rows
This class is the base class of all transformers in DS. If you need to write a transformer, first consider if DS::Transformer::Sub will do. It supports any kind of row-wise transformations where there is a one-to-one correspondence between incoming and outgoing rows.
DS::Transformer is a mixin of DS::Source and DS::Target.
Method for processing of ingoing data.
This method is supposed to be overridden.
By default it will return $row.
Constructor.
Instantiates an object of class $class,
taking the type $in_type,
returning the type $out_type,
attached to the source $source and attaced to the target $target.
Besides $class,
any of the parameters can be left out.
Attaches target $target to this object.
This method also triggers type checking,
ensuring that the outgoing type of this object is sufficient for $target.
If the type check fails,
an exception is thrown.
This is a method mostly for internal use. It will get or set the target, bypassing type checks.
Calling this metod will cause the transformer to pass $row to the target $target.
This is an accessor that gets or sets the outgoing type of this object.
Triggers processing of $row.
This method calls process with $row,
and then passes the result to pass_row.
Attaches $source as source.
This method also validates data types by calling validate_source_type,
throwing an exception if the validation fails.
Accessor for source. This method sets the source of this object and triggers type checking.
Validates source type.
If the $source_type is not valid,
it returns false,
true otherwise.
By default,
this method ensures that the ingoing type of this object contains no fields not specified in $source_type.
Override if you need more complex checking.
Accessor for ingoing type.
DS::Transformer::Sub, DS::Source, DS::Target.
Written by Michael Zedeler.
