Snippets Databases
Databases
Entity object
by: Pierre Wargnier
|
April 26, 2001
Version: 1.0
Type: Class
Category: Databases
License: GNU General Public License
Description: Object that map a table row in the object world. - Create object from DB (using table and key). - Create an HTML fragment for read only display of read-write (form). - Re-create object from POST variables in the page called by the form. - Save object to DB.
<?php
/*
====================================================================
Pierre WARGNIER - pierre.wargnier@laposte.net
====================================================================
entity.inc
====================================================================
====================================================================
2/7/2001 - version 1.0 Creation
====================================================================
ENTITY CLASS
====================================================================
The entity class is a base class. It is the mother of all these
objects that have to be stored into the database. Read method
headers to see what it can do!
Database interface:
------------------
I used a file called db_mysql.inc (Session Management for PHP,(C)
Copyright 1998 SH Online Dienst GmbH Boris Erdmann, Kristian
Koehntopp) that provides me with a $db object 4 methods of this
object are used here. The primary key of the table should be called
"id".
metadata(<X>): Returns an array of associative arrays, each
associative array represents a column in the table
called <X>. With the "name" key we have the name of
the field.
query(<X>): Execute a SQL statement <X>.
next_record(): Put a pointer on the next (first if called first) row
returned by a select query.
f(<X>): Returns the value of the field named <X> in the
selected row
usage
-----
Create the db object:
require_once('db_mysql.php');
class MYDBASE extends DB_Sql {
var $Host = '<host>';
var $Database = '<base>';
var $User = '<user>';
var $Password = '<password>';
}
$db = new MYDBASE;
This class can't be used directly, it has to be used in a derived
class where you will define the table variable.
class Object extends Entity {
var $table = 'object';
function Object($source,$id=''){
$this->Entity($source,$id);
}
}
If the page is a modification form:
$obj = new Object('db','<a key>');
echo '<form ...>';
echo '<input type="hidden" name="id" value="<a key>"';
echo $obj->form();
echo '</form>';
If the page is a page called by the form:
$obj = new Object('form', $id);
$obj->save();
*/
class Entity {
var $id; // entity id = table key
var $table; // the table were the entity is stored
/*
constructor method
--------------------------------------------------------------------
This constructor create the object. There are tree kind of object
creation, to choose one just use blank, db or form as the first
parameter and the id as second (for blank id is not required):
- creation of a new blanc object (blank)
- recall of an object stored in base (db),
- recall of an object transmited by a form (form)
If a object cannot be recalled from a form or db, the table is set
to '' (A way of saying that is a NULL entity).
*/
function Entity($source,$id=''){
if ($this->table == NULL) die('Can\'t instanciate virtual class Entity');
$this->id = $id;
global $db, $PREFIX;
$this->table = $PREFIX.$this->table;
//query the name of the properties
$fields = array();
$fields = $db->metadata($this->table);
foreach ($fields as $field){
$name = $field["name"];
if ($name != 'id'){
$this->{$name}='';
}
}
//query values if we recall object from db
if($source == 'db' and $id != NULL){
$query = 'SELECT ';
foreach (get_object_vars($this) as $key => $val){
if($key != 'id' and $key != 'table'){
$query .= $key.',';
}
}
$query = substr($query, 0, strlen($query) - 1);
$query .= ' FROM '.$this->table;
$query .= ' WHERE id=\''.$this->id.'\'';
$db->query($query);
if ($db->num_rows() == 1){
if($db->next_record()){
foreach (get_object_vars($this) as $key => $val){
if($key != 'id' and $key != 'table'){
$this->{$key} = $db->f($key);
}
}
}
}else{
$this->table ='';
}
//query values if we recall object from form
}elseif($source == 'form' and $id != NULL){
if(!isset($GLOBALS[$this->table.'_'.$this->id])){
$this->table ='';
}else{
foreach (get_object_vars($this) as $key => $val){
if($key != 'id' and $key != 'table'){
$temp = $GLOBALS[$this->table.'_'.$this->id.'_'.$key];
if (get_magic_quotes_gpc()){
$temp = stripslashes($temp);
}
$this->{$key} = $temp;
}
}
}
}
}
/*
isNull method
--------------------------------------------------------------------
This method should be called each time an object is created with the
db or form method to check if the id was valid.
*/
function isNull(){
if($this->table == '')
return TRUE;
return FALSE;
}
/*
dump method
--------------------------------------------------------------------
This is a debug only method. This method returns all the values
stored into an object in a HTML fragment.
*/
function dump(){
$ret = "<table>\n";
$ret .= '<tr><th>id</th><td>'.htmlspecialchars($this->id,ENT_NOQUOTES)."</td></tr>\n";
$ret .= '<tr><th>table</th><td>'.$this->table."</td></tr>\n";
$ret .= '<tr><th>class</th><td>'.get_class($this)."</td></tr>\n";
foreach(get_object_vars($this) as $key => $value){
if( $key != 'id' and $key != 'table'){
$ret .= '<tr><th>'.$key.'</th><td>'.htmlspecialchars($value,ENT_NOQUOTES)."</td></tr>\n";
}
}
$ret .= "</table>\n"; return $ret;
}
/*
form method
--------------------------------------------------------------------
This returns HTML code of a fragment of form that is used to modify
the object. Variables we be called <table>_<id>_<field name>. There
is a variable <table>_<id> that contains the name of the class.
*/
function form(){
$ret = "<table>\n";
$ret .= '<tr><th>id</th><td>'.htmlspecialchars($this->id,ENT_NOQUOTES)."</td></tr>\n";
$ret .= '<tr><th>class</th><td><input type="hidden" name="'.$this->table.'_'.htmlspecialchars($this->id,ENT_QUOTES).'" value="'.get_class($this).'">'.get_class($this)."</td></tr>\n";
$ret .= '<tr><th>table</th><td>'.$this->table."</td></tr>\n";
foreach(get_object_vars($this) as $key => $value){
if($key != 'id' and $key != 'table'){
$ret .= '<tr><th>'.$key.'</th><td><input type="text" name="'.$this->table.'_'.htmlspecialchars($this->id,ENT_QUOTES).'_'.$key.'" value="'.htmlspecialchars($value,ENT_QUOTES).'"></td></tr>'."\n";
}
}
$ret .= "</table>\n";
return $ret;
}
/*
script method
--------------------------------------------------------------------
This method returns the Javascripts statements that has to be
inserted into a SCRIPT element.
*/
function script(){
return TRUE;
}
/*
display method
--------------------------------------------------------------------
This returns HTML code used to display the object to the user. Now
it just call dump, but you can build a more fancy display.
*/
function display(){
return $this->dump();
}
/*
save method
--------------------------------------------------------------------
This method store (create or update) the object into the
database. If the object id property was not defined, the method put
the key used to store the object into the table. Return TRUE in case
of success.
*/
function save(){
global $db;
$this->delete();
foreach (get_object_vars($this) as $key => $val){
if( $key != 'type' and $key != 'table'){
$keys .= $key.',';
$vals .= '\''.addslashes($val).'\',';
}
}
$keys = ' ('.substr($keys, 0, strlen($keys) - 1).') ';
$vals = ' ('.substr($vals, 0, strlen($vals) - 1).') ';
$query = 'INSERT INTO '.$this->table.$keys.'VALUES'.$vals;
return($db->query($query));
}
/*
delete method
--------------------------------------------------------------------
Delete object from the database. Return TRUE if success.
*/
function delete(){
global $db;
if( $this->id != '' ){
return($db->query("DELETE FROM $this->table WHERE id='$this->id'"));
}
}
}
?>
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