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PHP - Class Building Question
Why is the proper way to call a class is to call a method at the same time?
For example Code: [Select] $class = new SomeClass(); $class->some_method(); I understand why you would do this but lets say you just have a simple class that you pass some data. The class than processes the data in some way than returns it. It is my understanding if you were to make a class likes this. Code: [Select] class SomeClass{ function __construct($data){ //process data// return $data; } } That this code is considered an improper way of doing this because you should never return data from the __construct. So would this follow code be the proper way to handle this? Code: [Select] class SomeClass{ function __construct($data){ $this->some_method($data); } function some_method($data){ //process data// return $data; } } Any good explanation on the proper way to handle this would be greatly appreciated. When I am making simple classes to do a specific task it would seem more efficient not having to know about any particular method inside the class. Similar TutorialsI'm starting to use a class to perform DB functions because I think it is more efficient. I found this class on the internet and understand pretty well what is going on. My problem is that I can't put the results on the screen when I use the class. (I can do it with out using the class but I'd like to learn to use it) function fetch($info) { return mysql_fetch_array($info); this is how I'm attempting to use it $db = new mysql; $db->connect(); while($row = $db->fetch($db->query("SELECT * FROM Attributes"))) { echo $row['Attribute']."<br>"; } This just echos the first row forever and I'm not sure how else to go about this. Any help would be appreciated. OK so sorry if my understandings a bit off, but if a I want to introduce a class into my doc is the best way to fo this with the include() function? heres an example of the code i have Code: [Select] class someclass { public function run($parm) { system($parm); } public static function create($item1,$item2) { $this->run($item1 . $item2); } } then i have a file that attempts to use the create method: someclass::create($one,$two); when interpreting, i get this error: "Using $this when not in object context in" does anyone know how I can fix this? I think I understand why its wrong (the class hasn't really been set up) - I just dont know how to correct it. Is there a way I can access class functions without using $this ? additionally I tried making the run method static too, but that didnt seem to work. Hi, I'm newbie to php opp. I just need to know if it is possible to instantiate a class like this? $import = new geoIpImportCSV(obtainDownloadFileName(), 'table1'); class geoIpImportCSV { private $input_zip_file; private $db_table; function __construct($input_zip_file, $db_table) { $this->input_zip_file = $input_zip_file; $this->db_table = $db_table; } /* "GeoLiteCity_" . $date . ".zip". */ function obtainDownloadFileName() { return "GeoLiteCity_20101201.zip"; } // ... } It is possible to call a method(obtainDownloadFileName()) like this to the constructor? Best Regards, Hello, I'm doing something that looks like framework. It's my first serious "project". And now, I have a few questions: what basic functions are needed in MVC model class? Just tell me some functions, that could use, so I could try to code them. And the next question is... I'm going to create a login system for users. In my website there will be pages, that are visible for all visitors, and only for members. For example main website page should be visible for all visitors, but the page, where member can change his password, should be visible only for member. I know only one way to do this: allways and everywhere check if user is logged in. But isn't there smarter and simpler way? I hope you understood what I need. Sorry for bad english I'm confused as to why assigning these variables in the class causes the page not to load... var $RootFolder = '/shyid/'; var $PagePath = str_replace($this->RootFolder, '', dirname($_SERVER['PHP_SELF'])); var $PageSections = explode('/', $this->PagePath); but when i set them on the page, everything works correctly? $head->RootFolder = '/shyid/'; $head->PagePath = str_replace($head->RootFolder, '', dirname($_SERVER['PHP_SELF'])); $head->PageSections = explode('/', $head->PagePath); Insight? Thanks. I created a database class to connect to a database. The code is below. I'm not sure how to call this connection in other classes. Do I use: $db->pdo = $conn->prepare($sql); or what? Note that the db object is instantiated at the end of the class file. Here is the class:
class DB {
public $pdo = '';
//public $message = 'A message from db'; // Debug
function __construct() {
// Database info located elsewhere
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "dbname";
try {
$this->pdo = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
// set the PDO error mode to exception
$this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} // End Try
catch(PDOException $e) {
echo "Error: " . $e->getMessage();
}
//echo '<h3>Everything wnet OK.</h3>'; // Debug
} // End __construct
} // End class definition DB.php
$db = new DB;
Thanks,
--Kenoli Imagine 6 PHP classes (one each for a product line), that have very similar coding structures, that go like this:
//function that computes stuff inside each of 6 files:
//they vary slightly from file to file but essentially it is this:
function computeFunction
{
$this->x = new X();
$this->x->calcD();
if ($this->x->dOk)
{
$this->x->calcE();
$this->x->calcN();
}
//more complicated logic that is essentially like above
//and by the way!
print $this->x->someVarThatIsUsedLater;
}
Then there is a single class like so :
class X
{
function calcD()
{
//compute some condition
if (<computed condition is met>) $this->dOk = true;
else $this->dOk = false;
//and by the way
$this->someVarThatIsUsedLater = 4;
}
}
Just to bring your attention to it, none of these functions return any result or value, but they nevertheless operate on variables of key interest via side-effects. That is, they modify variables that essentially act like globals, and then use those variables later ($this->dOk and $this->someVarThatIsUsedLater are one more prominent examples).
I need to untangle this mess. And make it clean and clear again, and make sense. How do I best proceed?
I have been wrestling with some ideas... like $this->dOk, can within reason be turned into a return variable of calcD() function, and then be tested against like if ($this->x->calcD()) and I think it will be reasonable enough. But then there are other functions that don't return anything and just act on variables via side-effects anyway so $this->dOk is one of the lesser troubles...
Other than that, what I am thinking of doing is getting rid of these mini-functions (calcE(), calcN(), etc.), removing them as a funciton, and putting their body directly into the code, as a first step to refactor. Many of the computations done inside are just a few lines of code anyway, and the functions kind of hide a lot of side-effects that happen, instead of actually encapsulating the behavior. So while it may be counter-intuitive to dismantle the functions that appear to be doing something that normally can be encapsulated (computing key variables E, N, etc), I think dismantling them will actually clean things up as far as collecting all the side-effects inside a single parent function thereby making them more visible.
Caveat: while doing so I will end up with 6 copies of untangled dismantled functions, because dismantling class X and putting its content into each of the 6 product line classes will have that effect.
But my hope is that from that point I will see more clearly to start identifying places where I can start to truly encapsulating the behavior via various structures, instead of masking it.
Problems / Questions:
I would like to but I am not entirely sure that I can skip that step of dismantling functions & the 6x multiplying effect. It's probably the same like skipping steps in solving polynomial equations. Some can do it and some need to list each step of their work.
And I am not entirely sure what structures I can replace it with in the end after I dismantle the functions.
It also looks like a lot of work. Is there a better way?
P.S. I already put tests on computeFunction() for each product line so I can be less paranoid about hacking stuff up.
Edited by dennis-fedco, 19 January 2015 - 03:06 PM. I have mysqli object in Database class base: [color=]database class:[/color] class Database { private $dbLink = null; public function __construct() { if (is_null($this->dbLink)) { // load db information to connect $init_array = parse_ini_file("../init.ini.inc", true); $this->dbLink = new mysqli($init_array['database']['host'], $init_array['database']['usr'], $init_array['database']['pwd'], $init_array['database']['db']); if (mysqli_connect_errno()) { $this->dbLink = null; } } } public function __destruct() { $this->dbLink->close(); } } Class derived is Articles where I use object dBLink in base (or parent) class and I can't access to mysqli methods (dbLink member of base class): Articles class: require_once ('./includes/db.inc'); class Articles extends Database{ private $id, .... .... $visible = null; public function __construct() { // Set date as 2009-07-08 07:35:00 $this->lastUpdDate = date('Y-m-d H:i:s'); $this->creationDate = date('Y-m-d H:i:s'); } // Setter .... .... // Getter .... .... public function getArticlesByPosition($numArticles) { if ($result = $this->dbLink->query('SELECT * FROM articles ORDER BY position LIMIT '.$numArticles)) { $i = 0; while ($ret = $result->fetch_array(MYSQLI_ASSOC)) { $arts[$i] = $ret; } $result->close(); return $arts; } } } In my front page php I use article class: include_once('./includes/articles.inc'); $articlesObj = new articles(); $articles = $articlesObj->getArticlesByPosition(1); var_dump($articles); [color=]Error that go out is follow[/color] Notice: Undefined property: Articles::$dbLink in articles.inc on line 89 Fatal error: Call to a member function query() on a non-object in articles.inc on line 89 If I remove constructor on derived class Articles result don't change Please help me I have an existing instance of my class Database, now I want to call that instance in my Session class, how would I go about doing this? If a class has a constructor but also has a static method, if I call the static method does the constructor run so that I can use an output from the constructor in my static method? --Kenoli Ok. I know you can pass the object of a class as an argument. Example: class A { function test() { echo "This is TEST from class A"; } } class B { function __construct( $obj ) { $this->a = $obj; } function test() { $this->a->test(); } } Then you could do: $a = new A(); $b = new B($a); Ok so that's one way i know of. I also thought that you could make a method static, and do this: (assuming class A's test is 'static') class B { function test() { A::test(); } } But that is not working. I'd like to know all possible ways of accomplishing this. Any hints are appreciated. thanks Hi Can you call Class A's methods or properties from Class B's methods? Thanks. Hey guys, I'm not exactly sure what the term used for this is, but I'll try explaining it very thoroughly. My site I'm building is this: http://r-gaming.net/urban-rp/home/ On index.php file, I would like it so you if you're logged in (I have a logged in system already scripted), you're able to post current news. Something like this: http://ls-rp.com/ Would anyone willing to help me by linking a tutorial to code this method 'latest news' tool? Would be greatly appreciated. Crayon Hi guys, I have recently been asked by a freinds to turn his web-site in to a CMS web site and i was just wondering if implementing it in php is the write way to go about it. I have never realy build anything like a CMS so if you guys have tips for me that would be spot on. Greetings freaks, I am trying to figure out how to build an array for the following purpose, and have just been spinning my wheels as it's a very new topic to me. I have a database with a table and the following important rows: ID, Parent, and Name. In this table, Parents are given the value 0 for 'Parent' and a unique 'ID' & 'Name' - children are given all unique 'ID' and 'Name' with the value for Parent being 'ID' of the Parent they belong to. Example: ( as 'ID', 'Parent', 'Name') 1, 0, John & 2, 1, Jane / 3, 0, Mark & 4, 3, Mary & 5, 3, Mindy. As you can see, the second names in each example (the children) are connected to their parents by the 'Parent' row, whereas the first names (the parents) are not associated with anybody else. What I would like to do is build an array that associates every child to the parent ([Parent] => child1 ). Simple MySQL grants me an array for the parents: $parent_pull = mysql_query('SELECT * FROM `table` WHERE Parent = 0') while($row = mysql_fetch_array($parent_pull)){ $name[] = $row['Name']; $id[] = $row['ID']; } Now, I want to be able to use the $id[]s to build arrays WHERE Parent = $id[]. I have tried in loops with $id[$i] & $i++ to cycle the array values, but PHP tells me there mysql_fetch_array() expects parameter 1 to be resource, boolean given ... on line 32. $i = 0 while($i < 10){ $child_pull = mysql_query('SELECT * FROM `table` WHERE Parent = $id[$i] '); $child = mysql_fetch_array($child_pull); $child[] = $child['Name']; <-- Line 32 $i++; } How would I go about pulling all the children and associating them with their parents? Hi people. I'm building a quiz with one correct answer out of possible 4. My problem is that after I choose a random answer (which is the correct one) I have problems with choosing random 3 wrong answers which are not the same as answer 1 (they all come from the same table). My first mysql query gives me back 1 row my second mysql query gives me back 15 row (there were 16 - 1 which is the correct one). How can take only 3 rows out of that second query and output them into variables that I can later echo into a form? Can you help me understand this problem or can you propose an alternative method to deal with this? Here are my two queries: Code: [Select] // Fetch random answer (correct) $query = "SELECT * FROM psychofarm_brand WHERE `id`=".$randomNumber; $result = mysql_query($query); $row = mysql_fetch_array($result); // Fetch wrong answer $query2 = "SELECT * FROM psychofarm_gen WHERE `id`!=".$randomNumber; $result2 = mysql_query($query2); $row2 = mysql_fetch_array($result2); I hope this is clear. Thanks Hi Guys I am trying to build a menu sing the code below, I can get the main headings, the problem arises when I try and produce the sub menus. Can someone please tell me where I am going wrong, or a better way of getting the desired result Code: [Select] <?php function submenu() { $submenu_sql=mysql_query("SELECT * FROM `tbl_menu` where `parent_menu_id` = '$menu_row[menu_id]'"); if(mysql_num_rows($submenu_sql)>0) { echo('<ul>'); while ($submenu_row=mysql_fetch_assoc($submenu_sql)) { echo('<li><a href="'.$submenu_row['link'].'">'.$submenu_row['menu_display'].'</a></li>'); } echo('</ul>'); }; } $menu_sql=mysql_query("SELECT * FROM `tbl_menu` where `parent_menu_id` = '0'"); if (mysql_num_rows($menu_sql)>0) { echo('<div id="accordian">'); while ($menu_row=mysql_fetch_assoc($menu_sql)) { echo('<div class="panel_container"> <h3><a href="'.$menu_row['link'].'">'.$menu_row['menu_display'].'</a></h3> <div class="panel_body">'); submenu(); echo('</div> </div>'); } echo('</div>'); } ?> I am getting the following error Notice: Undefined variable: menu_row in /home/sites/j-slink.co.uk/public_html/includes/menu.php on line 4 The desired result is to produce a menu with the following layout Code: [Select] <div id="accordion"> <div class="panel_container" id="panel1"> <h3 id="visible">Home</h3> <div id="panel1-body" class="panel_body"> </div> </div> <div class="panel_container" id="panel2"> <h3>Music</h3> <div id="panel2-body" class="panel_body"> <div> <ul> <li>Calling Card Mixing Tape</li> </ul> </div> </div> </div> <div class="panel_container" id="panel3"> <h3>Panel 3</h3> <div id="panel3-body" class="panel_body"> <div> This is the contents of this panel. </div> </div> </div> <div class="panel_container" id="panel4"> <h3>Panel 4</h3> <div id="panel4-body" class="panel_body"> <div> This is the contents of this panel. </div> </div> </div> <div class="panel_container" id="panel5"> <h3>Panel 5</h3> <div id="panel5-body" class="panel_body"> <div> This is the contents of this panel. </div> </div> </div> </div> Thanks in advance Hey guys, I'm currently trying to make a tutorial website, and I'd like to have a fairly simple blog / news page that I can update with pictures and news stories. I would also like people to be able to comment on these postings. I'm pretty new to PHP but i made a simple blog using a php handler and a database table, but I was just wondering is there some 3rd party application I can use to manage my website with like users and articles and such without having to use their website layout? Like, programs such as WordPress and PHP-Fusion, Joomla etc, dont let you use your own html and css pages do they? I want to keep my website but have something purely in the background for me to manage the content and maybe like paste some script to my actual pages or whatever. Im just lost is all I need a little guidance =] Thanks a bunch. In php how could I build a .net application? So I have a source that I want to build in .net, but i'm not sure how... |
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