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<?php
//-------------------------------------------------------------------
// gRESTbookData.php: handle the data for gRESTbook
//-------------------------------------------------------------------
// For more info, see: http://muellerware.org/projects/gRESTbook/
//-------------------------------------------------------------------
// Copyright (c) 2007 Patrick Mueller
// Using the MIT license:
// http://www.opensource.org/licenses/mit-license.php
//-------------------------------------------------------------------
// 2007/03/xx - Patrick Mueller - pmuellr@yahoo.com
//-------------------------------------------------------------------
// json encoder/decoder from Zend Framework
require_once 'Zend/Json.php';
//-------------------------------------------------------------------
// This class models the data associated with the gRESTbook
// application.
//-------------------------------------------------------------------
class GRESTbookEntry {
// first three fields are meta-data; end up in the URL or
// headers of HTTP requests/responses
public $id; // integer: id of the entry
public $dateModified; // integer: epoch seconds when entry modified
public $eTag; // string: hash of author::message
// next two fields are the business data for the class
public $author; // string: author of the entry
public $message; // string: message of the entry
//---------------------------------------------------------------
// Create from a JSON string - return a new instance of this
// class given a JSON string, but only sets the author and
// message fields; remaining fields from HTTP request info.
// Throw exception if invalid.
//---------------------------------------------------------------
static public function fromJSON($json) {
$map = Zend_Json::decode($json);
if (!isset($map['author'])) throw new Exception('author property is not set');
if (!isset($map['message'])) throw new Exception('message property is not set');
$result = new GRESTbookEntry();
$result->author = $map['author'];
$result->message = $map['message'];
$result->validate();
return $result;
}
//---------------------------------------------------------------
// Throw an exception if the business data is invalid.
//---------------------------------------------------------------
public function validate() {
if (!is_string($this->author)) throw new Exception('author is not a string');
if (!is_string($this->message)) throw new Exception('message is not a string');
if ($this->author == '') throw new Exception('author is an empty string');
if ($this->message == '') throw new Exception('message is an empty string');
return '';
}
//---------------------------------------------------------------
// Return a hash of the object (used for eTag)
//---------------------------------------------------------------
public function hash() {
return md5($this->author . '::' . $this->message);
}
//---------------------------------------------------------------
// Return JSON string, consisting of the author and message
// fields (remaining fields available via HTTP request or response).
//---------------------------------------------------------------
public function toJSON() {
$map = array();
$map['author'] = $this->author;
$map['message'] = $this->message;
return Zend_Json::encode($map);
}
//---------------------------------------------------------------
// Return a human readable string representation
//---------------------------------------------------------------
public function __toString() {
$result = __CLASS__ . '{' . "\n";
$result .= ' id: ' . $this->id . "\n";
$result .= ' dateModified: ' . $this->dateModified . "\n";
$result .= ' eTag: ' . $this->eTag . "\n";
$result .= ' author: ' . $this->author . "\n";
$result .= ' message: ' . $this->message . "\n";
$result .= '}';
return $result;
}
}
//-------------------------------------------------------------------
// This class handles the database access for the GRESTbook data.
//-------------------------------------------------------------------
class GRESTbookDB {
// our PDO database handle
private $db;
//---------------------------------------------------------------
// Connect to the database when the object is instantiated
//---------------------------------------------------------------
public function __construct() {
$this->db = new PDO('sqlite:gRESTbook.sq3', '', '');
}
//---------------------------------------------------------------
// Disconnect from the database when object is GC'd
//---------------------------------------------------------------
public function __destruct() {
$this->db = null;
}
//---------------------------------------------------------------
// CREATE a new GRESTbook entry. Expects the author and message
// fields to be set; dateModified, eTag and id will be available
// in the object returned, which will be the same object passed
// in.
//
// GRESTbookEntry on input:
// id: ignored
// dateModified: ignored
// eTag ignored
// author: value to set in DB
// message: value to set in DB
//
// GRESTbookEntry on output:
// id: id of new entry
// dateModified: current date
// eTag hash of author::message
// author: unchanged from input
// message: unchanged from output
//
// Returns the input object, suitably updated, on success,
// and null on failure.
//
// Can also throw an exception, including if the data is invalid.
//---------------------------------------------------------------
public function create($gRESTbookEntry) {
// validate input
$gRESTbookEntry->validate();
$db = $this->db;
// set up the SQL statement
$cmd = <<<CMD
insert into ENTRIES
(ID, DATE_MODIFIED, ETAG, AUTHOR, MESSAGE)
values (?,?,?,?,?)
CMD;
$stmt = $db->prepare($cmd);
if (false == $stmt) {
$err = $db->errorInfo();
throw new Exception("Error creating insert statement: " . $err[2]);
}
// set the dateModified and eTag fields
$newDate = time();
$newETag = $gRESTbookEntry->hash();
// parameters for prepared statement
$vars = array(
NULL,
$newDate,
$newETag,
$gRESTbookEntry->author,
$gRESTbookEntry->message
);
// execute, returning early if failure
$result = $stmt->execute($vars);
if (!$result) {
return null;
}
// if succcess, update fields in our data
$gRESTbookEntry->id = $db->lastInsertId();
$gRESTbookEntry->dateModified = $newDate;
$gRESTbookEntry->eTag = $newETag;
return $gRESTbookEntry;
}
//---------------------------------------------------------------
// READ a GRESTbook entry given an id.
//
// GRESTbookEntry on output:
// id: same as input $id
// dateModified: value from DB
// eTag value from DB
// author: value from DB
// message: value from DB
//
// Returns a fully populated object if found, otherwise null.
//
// Can also throw an exception.
//---------------------------------------------------------------
public function read($id) {
$db = $this->db;
// setup the SQL statement
$cmd = <<<CMD
select
DATE_MODIFIED, ETAG, AUTHOR, MESSAGE
from ENTRIES
where ID = ?
CMD;
$stmt = $db->prepare($cmd);
if (false == $stmt) {
$err = $db->errorInfo();
throw new Exception("Error creating select statement: " . $err[2]);
}
// execute the SQL
$stmt->execute(array($id));
$fetchResult = $stmt->fetch(PDO::FETCH_NUM);
// early return if we didn't find it
if (!$fetchResult) {
return null;
}
// found the entry! Set it up.
$result = new GRESTbookEntry();
$result->id = $id;
$result->dateModified = $fetchResult[0];
$result->eTag = $fetchResult[1];
$result->author = $fetchResult[2];
$result->message = $fetchResult[3];
return $result;
}
//---------------------------------------------------------------
// UPDATE a GRESTbook entry. Note that to prevent entries
// from inadvertantly being updated, the eTag value passed in
// must equal the eTag value of the entry currently in the
// database.
//
// GRESTbookEntry on input:
// id: id of entry to update
// dateModified: ignored
// eTag eTag of previous version of GRESTbookEntry
// author: value to set in DB
// message: value to set in DB
//
// GRESTbookEntry on input:
// id: unchanged from input
// dateModified: current date
// eTag hash of new author::message
// author: unchanged from input
// message: unchanged from input
//
// Returns the input object, suitably updated, on success,
// and null on failure.
//
// Can also throw an exception, including if the data is invalid.
//---------------------------------------------------------------
public function update($gRESTbookEntry) {
// validate the data
$gRESTbookEntry->validate();
$db = $this->db;
// new eTag and dateModified fields
$newETag = $gRESTbookEntry->hash();
$newDate = time();
// setup the SQL
$cmd = <<<CMD
update ENTRIES SET
DATE_MODIFIED = ?,
ETAG = ?,
AUTHOR = ?,
MESSAGE = ?
where
(ID == ?) AND (ETAG == ?)
CMD;
$stmt = $db->prepare($cmd);
if (false == $stmt) {
$err = $db->errorInfo();
throw new Exception("Error creating update statement: " . $err[2]);
}
// execute the SQL
$vars = array(
$newDate,
$newETag,
$gRESTbookEntry->author,
$gRESTbookEntry->message,
$gRESTbookEntry->id,
$gRESTbookEntry->eTag,
);
$result = $stmt->execute($vars);
// return early if not found.
if (0 == $result) {
return null;
}
if (0 == $stmt->rowCount()) {
return null;
}
// update the dateModified and eTag fiels in the object
$gRESTbookEntry->dateModified = time();
$gRESTbookEntry->eTag = $newETag;
return $gRESTbookEntry;
}
//---------------------------------------------------------------
// DELETE a GRESTbook entry. Note that to prevent entries
// from inadvertantly being updated, the eTag value passed in
// must equal the eTag value of the entry currently in the
// database.
//
// Returns true if successful, false on failure.
//---------------------------------------------------------------
public function delete($id, $eTag) {
$db = $this->db;
// setup SQL
$cmd = <<<CMD
delete from ENTRIES
where (ID = ?) AND (ETAG = ?)
CMD;
$stmt = $db->prepare($cmd);
if (false == $stmt) {
$err = $db->errorInfo();
throw new Exception("Error creating delete statement: " . $err[2]);
}
// execute SQL
$result = $stmt->execute(array($id, $eTag));
// return early on error
if (!$result) {
return false;
}
if (0 == $stmt->rowCount()) {
return false;
}
return true;
}
//---------------------------------------------------------------
// READ the GRESTbook entries.
//
// Returns an array of id's to the GRESTBook entries.
//---------------------------------------------------------------
public function query() {
$db = $this->db;
// setup the SQL
$cmd = <<<CMD
select
ID
from ENTRIES
CMD;
$stmt = $db->prepare($cmd);
if (false == $stmt) {
$err = $db->errorInfo();
throw new Exception("Error creating select statement: " . $err[2]);
}
// execute the SQL, return the output
$stmt->execute();
$result = $stmt->fetchAll(PDO::FETCH_COLUMN, 0);
return $result;
}
}
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muellerware.org: projects/gRESTbook gRESTbookData.php
