NexTrieve::DBI - convert DBI statement handle to NexTrieve Document sequence
use NexTrieve; $ntv = NexTrieve->new( | {method => value} ); $converter = $ntv->DBI( | {method => value} ); $docseq = $converter->Docseq( $ntv->Index( $resource )->Docseq,$sth ); $docseq->done;
The DBI object of the Perl support for NexTrieve. Do not create directly, but through the DBI method of the NexTrieve object;
The "dbi2ntvml" script is basically a directly configurable and executable wrapper for the NexTrieve::DBI module.
The conversion of a statementb handle consists of basically three phases:
- creating the NexTrieve::DBI object - setting the appropriate parameters - serializing the content hash to XML
More specifically, the following steps are performed.
You must create the NexTrieve::DBI object by calling the "DBI" method of the NexTrieve object. You can set any parameters directly with the creation of the object by specifying a hash with method names and values. Or you can set the parameters later by calling the methods on the object.
After the object is created, you will have to decide which fields in the statement handle should be used as id and text. You will also have to decide which fields of the content hash should appear as what attributes (see field2attribute) and/or texttypes (see field2texttype).
You should also think about extra attributes (see extra_attribute) and/or texttypes (see extra_texttype) that should be added to the XML that are not part of the statement handle. And you should consider if any conversions should be done on the information that is destined to become an attribute (see attribute_processor) or a texttype (see texttype_processor), before they are actually serialized into XML.
By setting up all of this information, you may find it handy to use the Resource method for setting up the basic resource-file that could be used by NexTrieve to index the XML generated by these settings.
When all of this is done, all of the information in the content hash as well as the remaining text (from the original HTML) are fed to a generic serialization routine that is also used by the NexTrieve::RFC822 and NexTrieve::HTML modules.
This serialization routine looks for any extra attributes and/or texttypes and processor routines, executes them in the correct order and generates the XML for the record that was provided on input.
If you want to access the XML, you can call the xml method, which is inherited from the NexTrieve module.
These methods create objects from the NexTrieve::DBI object.
$docseq = $converter->Docseq( $sth,'id','text','ampersandize','fetchrow_hashref' ); $index = $ntv->Index( $resource ); $converter->Docseq( $index->Docseq,$sth,'id','text','ampersandize','fetchrow_hashref' );
The Docseq method allows you to create a NexTrieve document sequence object (or NexTrieve::Docseq object) out of a DBI statement handle. This can either be used to be directly indexed by NexTrieve (through the NexTrieve::Index object) or to create the XML of the document sequence in a file for indexing at a later stage.
The first (optional) input parameter is an (already existing) NexTrieve::Docseq object that should be used. This can either be a special purpose NexTrieve::Docseq object as created by the NexTrieve::Index module, or a NexTrieve::Docseq object that was created earlier on which a second run of a statement handle needs to be added.
The second input parameter specifies the DBI statement handle on which the fetch method should be executed.
The third input parameter specifies the name of the field that should be considered to contain the "id" of the record. The default can be specified with the id method. If no default was specified previously, the name "id" will be assumed.
The fourth input parameter specifies the name of the field that should be considered to contain the "text" of the record. The default can be specified with the text method. If no default was specified previously, the name "text" will be assumed.
The fifth input parameter specifies the name of the normalization routine that should be used to create valid XML. The default can be specified with the normalize method. If no default was specified previously, the name "ampersandize" will be assumed.
The sixth input parameter specifies the name of the field that should be considered to contain the name of the method to perform the fetch for each record. The default can be specified with the fetch method. If no default was specified previously, the method "fetchrow_hashref" will be assumed.
For more information, see the NexTrieve::Docseq module.
$resource = $converter->Resource( | {method => value} );
The "Resource" method allows you to create a NexTrieve::Resource object from the internal structure of the NexTrieve::DBI.pm object. More specifically, it takes the information as specified with the "extra_attribute, , and methods and creates the <indexcreation" section of the NexTrieve resource file as specified on http://www.nextrieve.com/usermanual/2.0.0/ntvresourcefile.stm .
For more information, see the documentation of the NexTrieve::Resource module itself.
These methods change aspects of the NexTrieve::DBI object.
$converter->attribute_processor( 'attribute', key | sub {} );
The "attribute_processor" allows you to specify a subroutine that will process the contents of a specific attribute before it becomes serialized in XML.
The first input parameter specifies the name of the attribute as it will be serialized. Please note that this may not be the same as the name of the content hash field.
The second input parameter specifies the processor routine. See "PROCESSOR ROUTINES" for more information.
$encoding = $converter->DefaultInputEncoding; $converter->DefaultInputEncoding( encoding );
See the NexTrieve.pm module for more information about the "DefaultInputEncoding" method.
$converter->extra_attribute( [\$var | sub {}, attribute spec] | 'reset' );
The "extra_attribute" method specifies one or more attributes that should be added to the serialized XML, created from sources outside of the original statement handle.
Each input parameter specifies a single attribute as a reference to a list of parameters. These parameters consist of:
- a reference to a variable or subroutine - an attribute specification
If the first parameter in the list consists of a reference to a variable, then the value of that variable will be used for that attribute at the moment the XML is serialized. This could e.g. be an external counter variable.
If the first parameter in the list consists of a reference to a subroutine, then that subroutine is called as a processor routine when the XML is serialized. The first input parameter is the contents of the "id" field in the content hash and can e.g. be used by the processor routine for a database lookup. See "PROCESSOR ROUTINES" for more information.
The rest of the list consists of an attribute specification. See "ATTRIBUTE SPECIFICATION" for more information.
As a special function, the string "reset" may also be specified as the first input parameter to the method: it will then remove any extra attribute specifications from the object that were specified previously in the lifetime of the object.
$converter->extra_texttype( [\$var | sub {}, texttype spec] | 'reset' );
The "extra_texttype" method specifies one or more texttypes that should be added to the serialized XML, created from sources outside of the original statement handle.
Each input parameter specifies a single texttype as a reference to a list of parameters. These parameters consist of:
- a reference to a variable or subroutine - a texttype specification
If the first parameter in the list consists of a reference to a variable, then the value of that variable will be used for that texttype at the moment the XML is serialized. This could e.g. be an externally stored title.
The rest of the list consists of a texttype specification. See "TEXTTYPE SPECIFICATION" for more information.
As a special function, the string "reset" may also be specified as the first input parameter to the method: it will then remove any extra texttype specifications from the object that were specified previously in the lifetime of the object.
$converter->fetch( 'fetchrow_hashref' ); $fetch = $converter->fetch;
The "fetch" method indicates the name of the method that should be executed on the statement handle to obtain a reference to a hash. By default, the name used is "fetchrow_hashref", which is the name of the method used by the Perl "DBI" module for returning a reference to a hash for the next record from a statement handle.
You only need to call this method if the statement handle that you pass to the Document method is not capable of processing the "fetchrow_hashref" method.
$converter->field2attribute( 'title','date',['id',attribute spec] );
The "field2attribute" specifies how a key in the content hash should be mapped to an attribute in the serialized XML.
Each input parameter specifies a single mapping. It either consists of the key (which causes that key to be serialize as an attribute with the same name) or as a reference to a list.
If a parameter is a reference to a list, then the first element of that list is the key in the content hash. The rest of the list is then considerd to be an attribute specification (see "ATTRIBUTE SPECIFICATION" for more information).
So, for example, just the string 'title' would cause the content of the key "title" in the content hash to be serialized as the attribute "title".
As another example, the list "[qw(id filename string key-unique 1)]" would cause the content of the "id" to be serialized as the attribute "filename" and cause a complete resource-specification if the Resource method is called.
$converter->field2texttype( 'title',[qw(description whatitis 200)],'keywords' );
The "field2texttype" specifies how a key in the content hash should be mapped to a texttype in the serialized XML.
Each input parameter specifies a single mapping. It either consists of the key (which causes that key to be serialize as a texttype with the same name) or as a reference to a list.
If a parameter is a reference to a list, then the first element of that list is the key in the content hash. The rest of the list is then considerd to be a texttype specification (see "TEXTTYPE SPECIFICATION" for more information).
So, for example, just the string 'title' would cause the content of the key "title" in the content hash to be serialized as the texttype "title".
As another example, the list "[qw(description whatitis 200)]" would cause the content of the "description" key to be serialized as the texttype "whatitis" and cause a complete resource-specification if the Resource method is called.
$converter->id( 'id' ); $id = $converter->id;
The "id" method specifies which field in the reference to the hash returned by the fetch method, should be considered to be the "id" identifying this particular record. By default, the name "id" is assumed.
$converter->normalize( 'ampersandize' ); $normalize = $converter->normalize;
Before any text that is obtained from the statement handle is allowed to be inserted into XML, it needs to be normalized so that no invalid XML can be generated. There are two modes of normalization available:
- ampersandize
This should be used when the text is considered to be "normal" text without HTML or XML entities.
- normalize
This should be used when the text is considered to be "HTML" like in the sense that it may contain HTML or XML entities.
By default, "ampersandize" is assumed.
$converter->text( 'text' ); $text = $converter->text;
The "text" method specifies which field in the reference to the hash returned by the fetch method, should be considered to be the "text". The content of this field will be removed from the content hash before being processed. By default, the name "text" is assumed.
$converter->texttype_processor( 'attribute', key | sub {} );
The "texttype_processor" allows you to specify a subroutine that will process the contents of a specific texttype before it becomes serialized in XML.
The first input parameter specifies the name of the texttype as it will be serialized. Please note that this may not be the same as the name of the content hash field.
An attribute specification can be very simple: just the name of the attribute, e.g. 'date'. If you would like to use the Resource method to create the <indexcreation> section of the NexTrieve resource-file, then it is wise to add the type of attribute, key and multiplicity information as well, as described in http://www.nextrieve.com/usermanual/2.0.0/ntvresourcefile.stm .
A complete attribute specification would be "'date','number','notkey','1'". Which of course can be more easily expressed as "qw(date number notkey 1)".
Please note that future versions of NexTrieve may add more fields to the complete attribute specification. So watch this space for more info in the future.
Processor routines can be either a reference to an (anonymous) subroutine or a key to one of the available subroutines for doing standard conversions.
If a processor routine is a reference to an (anonymous) subroutine, then that subroutine should expect the following input parameters:
- the data to be processed - the name of the attribute it will be serialized to - the document object for which the XML will be serialized
The subroutine is expected to return the processed data.
If the second input parameter is a key, it must be one of the following:
- datestamp
Attempt to convert the input to a datestamp in the form YYYYMMDD. The Date::Parse module must be available for this to work.
- epoch
Attempt to convert the input to a Unix epoch time value (number of seconds since midnight Jan. 1st 1970 GMT). The Date::Parse module must be available for this to work.
- timestamp
Attempt to convert the input to a timestamp in the form YYYYMMDDHHMMSS. The Date::Parse module must be available for this to work.
Other keyed processor routines may be added in the future, so please check this space for additions.
A texttype specification can be very simple: just the name of the texttype, e.g. 'title'. If you would like to use the Resource method to create the <indexcreation> section of the NexTrieve resource-file, then it is wise to add any extra information as well, as described in http://www.nextrieve.com/usermanual/2.0.0/ntvresourcefile.stm .
A complete texttype specification would be "'title','200'". Which of course can be more easily expressed as "qw(title 200)", which would make the "title" twice as important in exact searches by default than the other texttypes.
Please note that future versions of NexTrieve may add more fields to the complete texttype specification. So watch this space for more info in the future.
Elizabeth Mattijsen, <liz@dijkmat.nl>.
Please report bugs to <perlbugs@dijkmat.nl>.
NexTrieve is no longer being supported.
Copyright (c) 1995-2003 Elizabeth Mattijsen <liz@dijkmat.nl>. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
The NexTrieve.pm and the other NexTrieve::xxx modules.
1 POD Error
The following errors were encountered while parsing the POD:
Nested L<> are illegal. Pretending inner one is X<...> so can continue looking for other errors.
To install NexTrieve, copy and paste the appropriate command in to your terminal.
cpanm
cpanm NexTrieve
CPAN shell
perl -MCPAN -e shell install NexTrieve
For more information on module installation, please visit the detailed CPAN module installation guide.