Postgres::Handler

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Our local updated perl docs. These enhanced notes will be published on our next push to CPAN.

Postgres::Handler

NAME

Postgres::Handler - Builds upon DBD::Pg for advanced CGI web apps

DESCRIPTION

Postgres::Handler builds upon the foundation set by DBI and DBD::Pg to create a superset of methods for tying together some of the basic interface concepts of DB management when used in a web server environment. Postgres::Handler is meant to build upon the strengths of DBD::Pg and DBI and add common usability features for a variety of Internet applications.

Postgres::Handler encapsulates error message handling, information message handling, simple caching of requests through a complete iteration of a server CGI request. You will also find some key elements that hook the CGI class to the DBI class to simplify data IO to & from web forms and dynamic pages.

SYNOPSIS

 # Instantiate Object
 #
 use Postgres::Handler;
 my $DB = Postgres::Handler->new(dbname=>'products',dbuser=>'postgres',dbpass=>'pgpassword');

 # Retrieve Data & List Records
 #
 $DB->PrepLEX('SELECT * FROM products');
 while ($item=$DB->GetRecord()) {
     print "$item->{PROD_ID}\t$item->{PROD_TITLE}\t$item->{PROD_QTY}\n";
 }

 # Add / Update Record based on CGI Form
 # assuming objCGI is an instatiated CGI object
 # if the CGI param 'prod_id' is set we update
 # if it is not set we add
 #
 my %cgimap;
 foreach ('prod_id','prod_title','prod_qty') { $cgimap{$_} = $_; }
 $DB->AddUpdate( CGI=>$objCGI     , CGIKEY=>'prod_id',
                 TABLE=>'products', DBKEY=>'prod_id',
                 hrCGIMAP=>\%cgimap
                );

REQUIRES

CGI::Carp

CGI::Util

Class::Struct

DBD::Pg 1.43 or greater (fixes a bug when fetching Postgres varchar[] array data)

DBI

DATA ACCESS METHODS

new()

Create a new Postgres::Handler object.

Parameters

 dbname => name of the database to connect to
 dbuser => postgres user
 dbpass => password for that user

Notes

Set the errortype' data element to 'simple' for short error messages.

 $self->data('errortype') = 'simple';

data()

Get/set the data hash - this is where data fields are stored for the active record.

dbh()

Returns the database handle for the DB connection.

dbpass()

Get/set postgres user's password.

dbname()

Get/set database name. Simple string name of the database.

dbuser()

Get/set postgres username.

sth()

Returns the statement handle for the active record selection.

PUBLIC METHODS

AddUpdate()

Adds a new record or updates an existing record in the database depending on whether or not a specific CGI parameter has been set.

Useful for processing a posted form that contains form fields that match data fields. Pre-populate the form field that contains the database key field and an update occurs. Set it to blank and a new record is added.

Your database key field should have a default value that is unique and should be set as type 'PRIMARY KEY'. We always use serial primary key to auto-increment our keys when adding new records.

Notes

If a key is provided but is doesn't match anything in the existing data then the update fails, UNLESS... CHECKKEY=> 1 in which case it will attempt to add the record.

Your CGI->DB key hash reference should look something like this: %mymap = ( tablefld_name => 'form_name', tablefld_ssn => 'htmlform_ssn' ); And is passed with a simple \%mymap as the hrCGIMAP parameter to this function.

Even better, name your CGI form fields the same thing as your Postgres DB field names. Then you can skip the map altogether and just provide the CGISTART variable. All fields that start with the the CGISTART string will be mapped. Want to map every field? Set CGISTART = '.'.

Parameters (Required)

 CGI       => a CGI object from the CGI:: module

 DBKEY     => the name of the key field within the table
              defaults to Postgres::Handler Object Property <table>!PGHkeyfld
              must be provided
                                  - or -
                             the <table>!PGHkeyfld option must have
              been setup when creating a new Postgres::Handler object

 TABLE     => the name of the table to play with

 CGISTART or hrCGIMAP must be set (see below)

Parameters (Optional)

 CGISTART  => map all CGI object fields starting with this string
              into equivalently named database fields
                                  only used when hrCGIMAP is not set

 CGIKEY    => the CGI parameter name that stores the data key
              defaults to DBKEY


 CHECKKEY  => set to 1 to perform ADD if the DBKEY is not found in the
              database.

 DBSTAMP   => the name of the timestamp field within the table
              defaults to Postgres::Handler Object Property <table>!PGHtimestamp

 DONTSTAMP => set to 1 to stop timestamping
              timestamp field must be set

 hrCGIMAP  => a reference to a hash that contains CGI params as keys and
              DB field names as values

 MD5      => the name of the md5 encrypted field within the table
              defaults to Postgres::Handler Object Property <table>!PGHmd5

 REQUIRED  => array reference pointing to array that holds list of CGI
              params that must contain data

 VERBOSE   => set to 1 to set lastinfo() = full command string
              otherwise returns 'INSERT' or 'UPDATE' on succesful execution

 BOOLEANS  => array reference pointing to the array that holds the list
              of database field booleans that we want to force to false
                                  if not set by the equivalently named CGI field

 RTNSEQ    => set to a sequence name and AddUpdate will return the value of this
              sequence for the newly added record.  Useful for getting keys back
                                  from new records.

Action

 Either adds or updates a record in the specified table.

 Record is added if CGI data key [1] is blank or if CHECKKEY is set
 and the value of the key is not already in the database.

 Record is updated if CGI data key [2] contains a value.

Returns

 1 for success, get message with lastinfo()
 0 for failure, get message with lasterror()

DoLE()

Do DBH Command and log any errors to the log file.

Parameters (positional only)

 [0] = SQL command
 [1] = Die on error
 [2] = return error on 0 records affected
 [3] = quiet mode (don't log via carp)

Returns

 1 for success
 0 for failure, get message with lasterror

Field()

Retreive a field from the specified table.

Parameters (required)

 DATA     => Which data item to return, must be of form "table!field"

 KEY      => The table key to lookup in the database
               Used to determine if our current record is still valid.
               Also used as default for WHERE, key value is searched for
               in the PGHkeyfld that has been set for the Postgres::Handler object.

Parameters (optional)

 WHERE   => Use this where clause to select the record instead of the key

 FORCE   => Force Reload

 HTML    => Return HTML Quoted Strings

Returns

 The value of the field.

 Returns 0 and lasterror() is set to a value if an error occurs
               lasterror() is blank if there was no error

Example

 my $objPGDATA = new Postgres::Handler::HTML ('mytable!PGHkeyfld' => 'id');
 my $lookupID = '01123';
 my $data = $objPGDATA->Field(DATA=>'mytable!prod_title', KEY=>$lookupID);

 my $lookupSKU = 'SKU-MYITEM-LG';
 my $data = $objPGDATA->Field(DATA=>'mytable!prod_title', WHERE=>"sku=$lookupSKU");

GetRecord()

Retrieves the record in a hash reference with uppercase field names.

Parameters (positional or named)

 [0] or -name     select from the named statement handle,
                  if not set defaults to the last active statement handle

 [1] or -rtype    type of structure to return data in
        'HASHREF' (default) - Returns a hashref via fetchrow_hashref('NAME_uc')
        'ARRAY' - Returns an array via fetchrow_array()
        'ITEM' - Returns a scalar via fetchrow()

 [2] or -finish   set to '1' to close the named statement handle after returning the data

Returns

The hashref or array or scaler on success. 0 for failure, get message with lasterror.

lasterror()

Retrieve the latest error produced by a Postgres::Handler object.

Returns

The error message.

lastinfo()

Retrieve the latest info message produced by a Postgres::Handler object.

Returns

The info message.

nsth()

Retrieve a named statement handle.

Returns

The handle, as requested.

PrepLE()

Prepare an SQL statement and returns the statement handle, log errors if any.

Parameters (positional or named)

        [0] or -cmd     - required -statement
        [1] or -exec    - execute flag (PREPLE) or die flag (PREPLEX)
        [2] or -die             - die flag     (PREPLE) or null     (PREPLEX)
        [3] or -param   - single parameter passed to execute
        [4] or -name    - store the statement handle under this name
        [5] or -aparam   - An array reference of multiple values to bind to the prepared statement

Returns

1 for success

PrepLEX()

Same as PrepLE but also executes the SQL statement

Parameters (positional or named)

        [0] or -cmd     - required -statement
        [1] or -die             - die flag     (PREPLE) or null     (PREPLEX)
        [2] or -param   - single parameter passed to execute
        [3] or -name    - store the statement handle under this name

Returns

1 for success

Quote()

Quote a parameter for SQL processing via the DBI::quote() function. Sets the data handle if necessary.

SEMI-PUBLIC METHODS

Using these methods without understanding the implications of playing with their values can wreak havoc on the code. Use with caution...

SetDH()

 Internal function to set data handles
 Returns Data Handle

 If you don't want the postgres username and password
 littering your perl code, create a subclass that
 overrides SetDH with DB specific connection info.

SetMethodParms()

 Allows for either ordered or positional parameters in
 a method call AND allows the method to be called as EITHER
 an instantiated object OR as an direct class call.

Parameters

 [0] - self, the instantiated object
 [1] - the class we are looking to instantiate if necessary
 [2] - reference to hash that will get our named parameters
 [3] - an array of the names of named parameters
       IN THE ORDER that the positional parameters are expected to appear
 [4] - extra parameters, positional or otherwise

Action

 Populates the hash refered to in the first param with keys & values

Returns

 An object of type class, newly instantiated if necessary.

Example

 sub MyMethod() {
        my $self = shift;
        my %options;
                $self = SetMethodParms($self,'MYCLASS::SUBCLASS', \%options, [PARM1,PARM2,PARM3], @_ );
        print $options{PARM1} if ($options{PARM2} ne '');
        print $options{PARM3};
 }

CGIMap()

 Prepare a hash reference for mapping CGI parms to DB fields
 typically used with AddUpdate() from Postgres::Handler.

Parameters

 hrCGIMAP       - reference to hash that contains the map
 CGI                    - the CGI object
 CGISTART       - map all fields starting with this text
 CGIKEY                 - the cgi key field
 BOOLEANS       - address to list of boolean fields

Example

 @boolist = qw(form_field1 form_field2);
 $item->CGIMap(CGI => $objCGI, hrCGIMAP=>\%cgimap, CGISTART=>'cont_', CGIKEY=>'cont_id', BOOLEANS=>\@boolist);

NOTES

Parameters (Named v. Positional)

Some methods allow for parameters to be passed in via both positional and named formats. If you decide to use named parameters with these "bi-modal" methods you must prefix the parameter with a hyphen.

Positional Example

 use Postgres::Handler;
 my $DB = Postgres::Handler->new(dbname=>'products',dbuser=>'postgres',dbpass=>'pgpassword');
 $DB->PrepLEX('SELECT * FROM products');

Named Example

 use Postgres::Handler;
 my $DB = Postgres::Handler->new(dbname=>'products',dbuser=>'postgres',dbpass=>'pgpassword');
 $DB->PrepLEX(  -cmd    =>      'SELECT * FROM products'        );

EXAMPLES

Short Program

 # Instantiate Object
 #
 use Postgres::Handler;
 my $DB = Postgres::Handler->new(dbname=>'products',dbuser=>'postgres',dbpass=>'pgpassword');

 # Retrieve Data & List Records
 #
 $DB->PrepLEX('SELECT * FROM products');
 while ($item=$DB->GetRecord()) {
        print $item->{PROD_ID}\t$item->{PROD_TITLE}\t$item->{PROD_QTY}\n";
 }

 # Add / Update Record based on CGI Form
 # assuming objCGI is an instatiated CGI object
 # if the CGI param 'prod_id' is set we update
 # if it is not set we add
 #
 my %cgimap;
 foreach ('prod_id','prod_title','prod_qty') { $cgimap{$_} = $_; }
 $DB->AddUpdate( CGI=>$objCGI     , CGIKEY=>'prod_id',
                 TABLE=>'products', DBKEY=>'prod_id',
                 hrCGIMAP=>\%cgimap
               );

AddUpdate Example

 # <form method="post" action="/thisapp.pl">
 # <input type="submit" name="submit" value="submit">
 # <input type="hidden" name="chat_id" value="">
 # <input type="text" name="chat_text" value="">
 # </form>

 use Postgres::Handler;
 use CGI;
 my $DB = Postgres::Handler->new(dbname=>'products',dbuser=>'postgres',dbpass=>'pgpassword');
 my $CGI = new CGI;
 my $AOK = $DB->AddUpdate(
           CGI     => $CGI,
           DBKEY   => 'chat_id',
           TABLE   => 'chatter',
           CGISTART=> 'chat_'
           );
 print ($AOK?'Awesome!':'Fail!');

AUTHOR

Cyber Sprocket Labs (CSL) is and advanced internet technology consulting firm based in Charleston South Carolina. We provide custom software, database, and consulting services for small to mid-sized businesses.

For more information visit our website at www.cybersprocket.com

COPYRIGHT

(c) 2008, Cyber Sprocket Labs

This script is covered by the GNU GENERAL PUBLIC LICENSE.

http://www.cybersprocket.com/wiki/index.php/GNU_General_Public_License

REVISION HISTORY

 v2.3 - May 2008
      Documentation cleanup.

 v2.2 - Apr 2006
      Fixed problem with SetDH database handle management


 v2.1 - Mar 2006
      Added RTNSEQ feature to AddUpdate so we can get back the key of a newly added record


 v2.0 - Feb 2006
      Moved CGI::Carp outside of the package to prevent perl -w warnings

 v1.9 - Feb 2006
      Update Field() to prevent SIGV error when WHERE clause causes error on statement
                Field() now returns 0 + lasterror() set to value if failed execute
                            returns fldval + lasterror() is blank if execution OK

 v1.8 - Jan 2006
      Bug fix on PrepLE and PrepLEX for perl -w compatability
                Added DoLE param to return error status (0) if the command affects 0 records '0E0'
                Added DoLE param to keep quiet on errors (do not log to syslog via carp)
                Documentation updates

 v1.5 - Nov 2005
                Fixed @BOOLEANS on AddUpdate to force 'f' setting instead of NULL if blank or 0

 v1.5 - Oct 2005
                Fixed return value error on AddUpdate()

 v1.4 - Aug 2005
      Minor patches

 v1.3 - Jul 17 2005
      Minor patches
                Now requires DBD::Pg version 1.43 or greater

 v1.2 - Jun 10 2005
      GetRecord() mods, added 'ITEM'
                test file fix in distribution
                created yml file for added requisites on CPAN


 v1.1 - Jun 9 2005
      pod updates
                Field() cache bug fix
                GetRecord() expanded, added finish option
                Moved from root "PGHandler" namespace to better-suited "Postgres::Handler"

 v0.9 - May 2 2005
      pod updates
                AddUpdate() updated, CGIKEY optional - defaults to DBKEY
                AddUpdate() updated, BOOLEANS feature added
                GetRecord() updated, added check for sth active before executing
                Field() fixed hr cache bug and data bug and trap non-set hr issue

 v0.8 - Apr 26 2005
      Fixed GetRecord() (again) - needed to check $DBI::errstr not $err

 v0.7 - Apr 25 2005
      Added error check on ->Field to ensure hashref returned from getrecord
      Added CGIMAP method
      Invoke CGIMAP from within AddUpdate if missing map
      Fixed GetRecord Return system

 v0.5 - Apr/2005
      Added DBI error trap on DoLE function
      Added named statement handles for multiple/nested PrepLE(X) capability
      Added VERBOSE mode to AddUpdate
      Added NAME to retrieved named statements via GetRecord
      Updated FIELD to use named statement handles

 v0.4 - Apr/2005
                Fixed some stuff

 v0.3 - Apr/2005
      Added REQUIRED optional parameter to AddUpdate
      Improved documentation
      Quoted DBKEY on add/update to handle non-numeric keys

 v0.2 - Mar/2005 -
      Added error messages to object
      Fixed issues with Class:Struct and the object properties
      Updated AddUpdate to use named parameters (hash) for clarity

 v0.1 - Dec/2004
      Initial private release


[edit]

CPAN

You can find the published version of Postgres::Handler under the Cyber Sprocket Labs account on CPAN.

Retrieved from "http://www.cybersprocket.com/wiki/index.php/Postgres::Handler"
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