i use classes for some typical MySQL queries, like getting specific users, news etc. And afterwards I call function query(), which calls mysqli class and query and returns the query like this:
class Users {
[...]
public function query() {
$mysql = new mysqli([...]);
$mysql->query($this->query);
return $mysql;
}
}
When I use it for ex. in $variable like:
$variable = new Users();
$variable->setNew($params)->query();
I have still stored object of Users in $variable. Is there any way to automatically 'update' the variable to be object of mysqli_result (in this case or different class in simillar situation) without using $variable = $variable->setNew($params)->query();?
Thank you for your advice.
You can do this in a one liner:
$variable = (new Users())->setNew($params)->query();
$variable now contains the return of query()
Related
I am wondering that whether it is possible to write two different mysql queries in one php class object method and use those results in an another class method. Here's I am trying to do (I put only the relevant part of my code here), but I think it's not working:
<?php
public function sql()
{
$sql = "SELECT * FROM customers";
// Another sql
$sql_sales = "SELECT SUM(sales) as sales FROM customers";
// Execute this sql and result is stored in a variable
$this->sales = $row['sales'];
return $sql;
}
public function customers_list()
{
$sql = $this->sql();
$customers = '
<div id="customers">
<div id="customers_num"><span>'.$this->sales.'</span> Sales</div>
</div>';
return $customers;
}
?>
Can we use value of variable $this->sales inside another method?
If not then what's the correct way of getting it's value?
In case your code is inside a class and you're using an instantiated object :
From PHP basics
The pseudo-variable $this is available when a method is called from
within an object context. $this is a reference to the calling object
Therefore you can access any of your object properties inside its methods.
In your specific case $this->sales = $row['sales']; stores a value in its sales
property which can be used anywhere else in the object scope.
We can not get variable value like your approach. Your main query $sql is returning the result but the value of your second query $sql_sales is nowhere returned. That's why it is undefined property in your method customers_list().
The solution is to create a separate method to get $this->sales value. Then you can call this method in your customers_list() and access its value.
I have the following class with several properties and a method in PHP (This is simplified code).
class Member{
public $Name;
public $Family;
public function Fetch_Name(){
for($i=0;$i<10;$i++){
$this[$i]->$Name = I find the name using RegExp and return the value to be stored here;
$this[$i]->Family = I find the family using RegExp and return the value to be stored here;
}
}//function
}//class
In the function Fetch_Name(), I want to find all the names and families that is in a text file using RegExp and store them as properties of object in the form of an array. But I don't know how should I define an array of the Member. Is it logical or I should define StdClass or 2-dimension array instead of class?
I found slightly similar discussion here, but a 2 dimensional array is used instead of storing data in the object using class properties.
I think my problem is in defining the following lines of code.
$Member = new Member();
$Member->Fetch_name();
The member that I have defined is not an array. If I do define it array, still it does not work. I did this
$Member[]= new Member();
But it gives error
Fatal error: Call to a member function Fetch_name() on a non-object in
if I give $Member[0]= new Member() then I don't know how to make $Member1 or Member[2] or so forth in the Fetch_Name function. I hope my question is not complex and illogical.
Many thanks in advance
A Member object represents one member. You're trying to overload it to represent or handle many members, which doesn't really make sense. In the end you'll want to end up with an array that holds many Member instances, not the other way around:
$members = array();
for (...) {
$members[] = new Member($name, $family);
}
Most likely you don't really need your Member class to do anything really; the extraction logic should reside outside of the Member class, perhaps in an Extractor class or something similar. From the outside, your code should likely look like this:
$parser = new TextFileParser('my_file.txt');
$members = $parser->extractMembers();
I think you should have two classes :
The first one, Fetcher (or call it as you like), with your function.
The second one, Member, with the properties Name and Family.
It is not the job of a Member to fetch in your text, that's why I would make another class.
In your function, do your job, and in the loop, do this :
for($i = 0; $i < 10; ++$i){
$member = new Member();
$member->setName($name);
$member->setFamily($family);
// The following is an example, do what you want with the generated Member
$this->members[$i] = $member;
}
The problem here is that you are not using the object of type Member as array correctly. The correct format of your code would be:
class Member{
public $Name;
public $Family;
public function Fetch_Name(){
for($i=0;$i<10;$i++){
$this->Name[$i] = 'I find the name using RegExp and return the value to be stored here';
$this->Family[$i] = 'I find the family using RegExp and return the value to be stored here';
}
}
}
First, $this->Name not $this->$Name because Name is already declared as a member variable and $this->Name[$i] is the correct syntax because $this reference to the current object, it cannot be converted to array, as itself. The array must be contained in the member variable.
L.E: I might add that You are not writing your code according to PHP naming standards. This does not affect your functionality, but it is good practice to write your code in the standard way. After all, there is a purpose of having a standard.
Here you have a guide on how to do that.
And I would write your code like this:
class Member{
public $name;
public $family;
public function fetchName(){
for($i=0;$i<10;$i++){
$this->name[$i] = 'I find the name using RegExp and return the value to be stored here';
$this->family[$i] = 'I find the family using RegExp and return the value to be stored here';
}
}
}
L.E2: Seeing what you comented above, I will modify my answer like this:
So you are saying that you have an object of which values must be stored into an array, after the call. Well, after is the key word here:
Initialize your object var:
$member = new Memeber();
$memebr->fechNames();
Initialize and array in foreach
$Member = new Member();
foreach ($Member->Name as $member_name){
$array['names'][] = $member_name;
}
foreach ($Member->Family as $member_family) {
$array['family'][] = $member_family;
}
var_dump($array);
Is this more of what you wanted?
Hope it helps!
Keep on coding!
Ares.
Codeigniter can return a database query as generic "Object" like:
$q = $this->db->get("some_table");
$obj = $this->q->row();
$var = $obj->some_property
In my case I want to make a PHP class who's public variables are 1 for 1 with the database columns, along with some public methods. Is there a quick one-shot way to cast or convert the generic "Row" object into my custom class object? I've read posts that hint that it is certainly possible, but most involve a really hacky serialize/deserialize solution. In the past I have just done:
public function __construct($row) {
$this->prop = $row->prop;
$this->id = $row->id;
$this->value = $row->value;
}
And I find this is very tedious and makes ugly code.
See the third section under result():
CodeIgniter User Guide: Generating Query Results
You can also pass a string to result() which represents a class to instantiate for each result object (note: this class must be loaded)
$query = $this->db->query("SELECT * FROM users;");
foreach ($query->result('User') as $row)
{
echo $row->name; // call attributes
echo $row->reverse_name(); // or methods defined on the 'User' class
}
This question already has an answer here:
How to call the constructor with call_user_func_array in PHP
(1 answer)
Closed 7 years ago.
I have searched many a page of Google results as well as here on stackoverflow but cannot find a solution that seems to fit my situation. I appear to have but one last snag in the function I am trying to build, which uses call_user_func_array to dynamically create objects.
The catchable fatal error I am getting is Object of class Product could not be converted to string. When the error occurs, in the log I get five of these (one for each argument): PHP Warning: Missing argument 1 for Product::__construct(), before the catchable fatal error.
This is the code of the function:
public static function SelectAll($class, $table, $sort_field, $sort_order = "ASC")
{
/* First, the function performs a MySQL query using the provided arguments. */
$query = "SELECT * FROM " .$table. " ORDER BY " .$sort_field. " " .$sort_order;
$result = mysql_query($query);
/* Next, the function dynamically gathers the appropriate number and names of properties. */
$num_fields = mysql_num_fields($result);
for($i=0; $i < ($num_fields); $i++)
{
$fetch = mysql_fetch_field($result, $i);
$properties[$i] = $fetch->name;
}
/* Finally, the function produces and returns an array of constructed objects.*/
while($row = mysql_fetch_assoc($result))
{
for($i=0; $i < ($num_fields); $i++)
{
$args[$i] = $row[$properties[$i]];
}
$array[] = call_user_func_array (new $class, $args);
}
return $array;
}
Now, if I comment out the call_user_func_array line and replace it with this:
$array[] = new $class($args[0],$args[1],$args[2],$args[3],$args[4]);
The page loads as it should, and populates the table I am building. So everything is absolutely functional until I try to actually use my $args array within call_user_func_array.
Is there some subtle detail about calling that array that I am missing? I read the PHP manual for call_user_func_array once, and then some, and examples on that page seemed to show people just building an array and calling it for the second argument. What could I be doing wrong?
You can't call the constructor of $class like this:
call_user_func_array (new $class, $args);
That's no valid callback as first parameter. Let's pick this apart:
call_user_func_array (new $class, $args);
Is the same as
$obj = new $class;
call_user_func_array ($obj, $args);
As you can see, the constructor of $class has been already called before call_user_func_array comes into action. As it has no parameters, you see this error message:
Missing argument 1 for Product::__construct()
Next to that, $obj is of type object. A valid callback must be either a string or an array (or exceptionally a very special object: Closure, but that's out of discussion here, I only name it for completeness).
As $obj is an object and not a valid callback, so you see the PHP error message:
Object of class Product could not be converted to string.
PHP tries to convert the object to string, which it does not allow.
So as you can see, you can't easily create a callback for a constructor, as the object yet not exists. Perhaps that's why you were not able to look it up in the manual easily.
Constructors need some special dealing here: If you need to pass variable arguments to a class constructor of a not-yet initialize object, you can use the ReflectionClass to do this:
$ref = new ReflectionClass($class);
$new = $ref->newInstanceArgs($args);
See ReflectionClass::newInstanceArgs
Not possible using call_user_func_array(), because (as the name suggest) it calls functions/methods, but is not intended to create objects, Use ReflectionClass
$refClass = new ReflectionClass($class);
$object = $refClass->newInstanceArgs($args);
Another (more design-based) solution is a static factory method
class MyClass () {
public static function create ($args) {
return new self($args[0],$args[1],$args[2],$args[3],$args[4]);
}
}
and then just
$object = $class::create($args);
In my eyes it's cleaner, because less magic and more control
I use this for singleton factory pattern, becouse the ReflectionClass brokes the dependence tree, I hate the use of eval but its the only way to i find to simplificate the use of singleton pattern to inject mockObjects whith PHPUnit whitout open the class methods to that injection, BE CAREFULL WHITH THE DATA WHAT YOU PASS TO eval FUNCTION!!!!!!!! YOU MUST BE SURE THAT IS CLEANED AND FILTERED!!!
abstract class Singleton{
private static $instance=array();//collection of singleton objects instances
protected function __construct(){}//to allow call to extended constructor only from dependence tree
private function __clone(){}//to disallow duplicate
private function __wakeup(){}//comment this if you want to mock the object whith php unit jejeje
//AND HERE WE GO!!!
public static function getInstance(){
$a=get_called_class();
if(!array_key_exists($a, self::$instance)){
if(func_num_args()){
/**HERE IS THE CODE **//
$args=func_get_args();
$str='self::$instance[$a]=new $a(';
for($i=0;$i<count($args);$i++){
$str.=(($i)?",":"").'$args['.$i.']';
}
eval($str.");");//DANGER, BE CAREFULLY...we only use this code to inject MockObjects in testing...to another use you will use a normal method to configure the SingletonObject
/*--------------------------*/
}else{
self::$instance[$a]=new $a();
}
}
return self::$instance[$a];
}
}
And to use that:
class MyClass extends Singleton{
protected function __construct(MyDependInjection $injection){
//here i use the args like a normal class but the method IS PROTECTED!!!
}
}
to instanciate the object:
$myVar= MyClass::getInstance($objetFromClassMyDependInjection);
it calls the constructor whith the args I pased. i know that i can get the same result extending the static method getInstance but to teamworking its more easy to use this way
I've got a PHP database class which connects to MySQL and wraps up all the PDO code and I use it to query the database. Basically in the page controller I make a new object:
$db = new Database($dbConfig);
Then I can get data from the database like so using a prepared query:
$params = array('username' => $username);
$result = $db->preparedSelect('select password, salt from users where username = :username', $params);
Which copies the PDO statement results into a new assoc array and returns just the database results back to the calling page. I iterate through them with a simple foreach like so:
foreach ($result as $key => $val)
{
$password = $val['password'];
$salt = $val['salt'];
}
Ok so lets say I want another class to use my $db object so it can access the database in some of the methods. At the moment the other class looks like this:
class General
{
// Database object
private $db;
public function __construct($db)
{
$this->db = $db;
}
}
That works well but I'm just wondering if the constructor should look like this:
public function __construct(&$db)
{
$this->db = $db;
}
That should mean I'm passing it in via reference and not copying the object into the other class. I don't want a copy of the $db object inside the class, I want it to use the existing database object so I don't have multiple copies of it floating around using up memory.
Is there any difference in PHP5 between passing it in as $db or &$db? From doing some reading, PHP5 by default passes objects by reference, and other people saying it now does it the Java way and some say using the & makes a hard link whatever that is. I'm confused. What's the best way to do it?
Many thanks!
There is a difference, but it's not really the difference you may think.
In PHP5, "$db" holding an object is basically equivalent to a "Foo *" in C or C++. In other words, $db doesn't store the whole object, it just stores a small token that lets the code find the object when necessary. When you pass this token by value, it's as fast as passing an integer value rather than a copy of the entire object. But if you assign $db, it doesn't change the value in the caller because you're changing your local variable holding the token to contain a different token.
If the function takes "&$db", that's basically the equivalent of passing "Foo **" in C, or more correctly a function taking a "Foo *&" in C++. The call is just as fast since it's the same size thing that's being passed, but inside the function if you assign to $db it will change the value of $db in the caller because the "pass by reference" variable points you to the memory location holding the token in the caller.
The best way to do it is to pass by value (do not use "&") unless you know what you're doing and why you're doing it.
That's a good question.
You can always do a test by opening a $db handle, passing it to a function, and checking them via the === operator to make sure they are the same object.
This would be a good job for static methods. That is how many frameworks accomplish the same task.
class DB
{
private static $db = FALSE:
public static function init($dbConfig)
{
if(! self:$db)
{
self::$db = new Database($dbConfig);
}
}
public static function preparedSelect($sql, $params)
{
if(! self::$db)
{
die("call the init method first");
}
// db stuff, where you would call $this->db call self::$db
}
}
So in your other classes where you want to make calls to the database all you would have to do is:
class General
{
public function __construct()
{
DB::init($dbConfig);
}
public function someMethod()
{
$params = array('username' => $username);
$result = DB::preparedSelect('select password, salt from users where username = :username', $params);
}
}