How to create a select list using PHP OOP - php

Question

I've started recoding a PHP project into OOP. One thing I can't work out among many is how to make a dynamic select list. I have many lookup select lists to make. What's the best way to go about it?
I made a DatabaseObject class which has all my generic database queries in it. Do I add them here or make a special class for them, and how do I go about coding it?
require_once("database.php");
class DatabaseObject {
protected static $table_name;
// find all from a specific table
public static function find_all(){
global $database;
return static::find_by_sql("SELECT * FROM ".static::$table_name);
}
// select all from a specific table
public static function find_all_from($table){
global $database;
return static::find_by_sql("SELECT * FROM " .$table);
}
// find all from a specific table
public static function find_by_id($id){
global $database;
$result_array = static::find_by_sql("
SELECT * FROM ".static::$table_name. " WHERE id = '{$id}' LIMIT 1");
// return the data only for the one user
return !empty($result_array) ? array_shift($result_array) : false;
}
// find using sql
public static function find_by_sql($sql=""){
global $database;
// return all data from sql
$result_set = $database->query($sql);
$object_array = array();
while($row = $database->fetch_array($result_set)){
$object_array[] = static::instantiate($row);
}
return $object_array;
}
protected static function instantiate($record){
$class_name = get_called_class();
$object = new $class_name;
foreach($record as $attribute=>$value){
if($object->has_attribute($attribute)){
$object->$attribute = $value;
}
}
return $object;
}
protected function has_attribute($attribute){
$object_vars = $this->attributes();
// here we only want to know if the key exist
// so we will return true or false
return array_key_exists($attribute, $object_vars);
}
protected function attributes() {
$attributes = array();
foreach(static::$db_fields as $field) {
if(property_exists($this,$field)) {
$attributes[$field]= $this->$field;
}
}
return $attributes;
}
protected function sanitised_attributes() {
global $database;
$clean_attributes = array();
foreach($this->attributes() as $key => $value){
$clean_attributes[$key] = $database->escape_value($value);
}
return $clean_attributes;
}
public function save() {
// A new object won't have an id yet
return isset($this->id) ? $this->update() : $this->create();
}
// create new
protected function create() {
global $database;
$attributes =$this->sanitised_attributes();
$sql = "INSERT INTO ".static::$table_name." (";
$sql .= join(", " ,array_keys($attributes));
$sql .= ") VALUES ( '";
$sql .= join("', '" ,array_values($attributes));
$sql .= "')";
if($database->query($sql)) {
$this->id = $database->insert_id();
return true;
} else {
return false;
}
}
// update details
protected function update() {
global $database;
$attributes =$this->sanitised_attributes();
$attribute_pairs = array();
foreach($attributes as $key => $value) {
$attribute_pairs[] = "{$key}='{$value}'";
}
$sql = "UPDATE " .static::$table_name. " SET ";
$sql .= join(", ",$attribute_pairs);
$sql .= " WHERE id=". $database->escape_value($this->id);
$database->query($sql);
return ($database->affected_rows() ==1) ? true : false ;
}
public function delete() {
global $database;
$sql = "DELETE FROM ".static::$table_name;
$sql .= " WHERE id =". $database->escape_value($this->id);
$sql .= " LIMIT 1";
$database->query($sql);
return ($database->affected_rows() ==1) ? true : false ;
}
}

Answer 1

I would definitely model the select list as an object, since it has a well defined responsibility that can be encapsulated. I would go for keeping it as decoupled as possible from the DatabaseObject so that changes in any of those classes don't affect the other. As an example consider:
class SelectList
{
protected $options;
protected $name;
public function __construct($name, $options)
{
$this->options = $options;
$this->name = $name;
}
public function render()
{
$html = "<select name='" . $this->name . "'>\n";
foreach ($this->options as $option)
{
$html .= $option->render();
}
$html .= "</select>\n";
return $html;
}
}
class SelectListOption
{
protected $label;
protected $value;
protected $isSelected;
public function __construct($label, $value, $isSelected = false)
{
//Assign the properties
}
public function render()
{
$html .= '<option value="' . $this->value . '"';
if ($this->isSelected)
{
$html .= ' selected="selected" ';
}
$html .= '>' . $this->label . "</option>\n";
}
}
The one thing I like about modeling things this way is that adding new features (e.g. CSS styles for selected/unselected items, or the disabled attribute) is quite easy, since you know in which object that new feature belongs. Also, having this kind of "small" objects make it quite easy to write unit tests.
HTH

Answer 2

Just create a method which returns an HTML select/options view, by iterating over an associative array passed to the method...? Something like this maybe:
public static function viewSelect($name = "select", $arr_options = array()) {
$html = "<select name='$name'>\n";
foreach ($arr_options as $key => $val) {
$html .= "<option value='$key'>$val</option>\n";
}
$html .= "</select>\n";
return $html;
}
Then just pass the result from one of your database queries to this method. You could put this method into any appropriate class you want to.

Answer 3

You can also add selected option functionality
public static function viewSelect($name = "select", $arr_options =
array(), $selected) {
$selectedhtml = "";
$html = "<select name='$name'>\n";
foreach ($arr_options as $key => $val) {
if($key == $selected) $selectedhtml = "selected";
$html .= "<option value='$key' $selectedhtml>$val</option>\n";
}
$html .= "</select>\n";
return $html; }

Answer 4

public function get_posts()
{
$query="select * from tbl_posts";
$result= mysql_query($query);
$i=0;
while($data= mysql_fetch_assoc($result))
{
foreach($data as $key=>$value)
{
$info[$i][$key]=$value;
}
$i++;
}
return $info;
}