PHP - set object property within another object's array

Question

I still learning PHP, so please forgive my ignorance...

I have an object with 3 properties, two of which are arrays. One of the 2 arrays is an array of objects. I am having an issue setting the properties of and object within the array.

A var_dump of the master object contains the following (I separated the 3 variables for easier recognition):

object(Blockchain)#1 (4) { 
["chain"]=> array(1) { 
    [0]=> object(Block)#2 (5) { ["timestamp"]=> string(10) "05/27/2018" ["transaction"]=> array(2) { ["amount"]=> string(1) "0" ["uid"]=> string(18) "EMG: Genesis Block" } ["previousHash"]=> string(1) "0" ["hash"]=> string(64) "9e2838eb493cc112b2d3fd37925953d25cf9fd2ba4bf7e09750f368451f2ff03" ["nonce"]=> int(0) } } 

["difficulty"]=> int(4) 

["pendingTransactions"]=> array(2) { 

    [0]=> object(Transaction)#3 (4) { 
        ["fromAddress"]=> NULL ["toAddress"]=> NULL ["amount"]=> NULL ["pendingTransactions"]=> object(stdClass)#4 (1) { ["tranaction"]=> object(stdClass)#5 (3) { ["fromAddress"]=> string(9) "address-1" ["toAddress"]=> string(9) "address-2" ["amount"]=> int(100) } } } 

    [1]=> object(Transaction)#6 (4) { 
        ["fromAddress"]=> NULL ["toAddress"]=> NULL ["amount"]=> NULL ["pendingTransactions"]=> object(stdClass)#7 (1) { ["tranaction"]=> object(stdClass)#8 (3) { ["fromAddress"]=> string(9) "address-2" ["toAddress"]=> string(9) "address-1" ["amount"]=> int(25) } } } } ["miningReward"]=> int(100) }

I am trying to set the fromAddress property in the pendingTransactions array that is part of the Transactions object.

The code I attempted to write is as follows:

class Transaction {
public $fromAddress = "";
public $toAddress = "";
public $amount = "";

public function __construct ($fromAddress, $toAddress, $amount) {
    $this->pendingTransactions->{Tranaction}->fromAddress = $fromAddress;
    $this->pendingTransactions->{Tranaction}->toAddress = $toAddress;
    $this->pendingTransactions->{Tranaction}->amount = $amount;
}

public function __toString() {
    return $this->pendingTransactions->tranaction->fromAddress . ", " . $this->pendingTransactions->tranaction->toAddress . ", " . $this->pendingTransactions->tranaction->amount;
}

}

Any assistance would be greatly appreciated.

Already read the following posts:

PHP - get properties of an object in an array PHP - get properties of an object in an array? @clerksx @Sampson

Accessing PHP Array Object Protected Property Accessing PHP Array Object Protected Property @Aayush @j0k

Php: Cannot seem to access array property in object Php: Cannot seem to access array property in object @OllyBarca @Tobias Golbs Edit: misspelled fromAddress - before: fromAddtress

I can't get how do you plan to use $this->pendingTransactions in __construct no any property is defined yet when you are in constructor. And I don't see any pendingTransactions property defined — Alex
– Alex, Commented May 28, 2018 at 16:56
@Alex, I agree I have a design issue. Pending transactions should not be a part of the Blockchain object. Pending transactions and completed transactions are mutually exclusive. I will change my design and update my code to reflect the change. — EricG
– EricG, Commented May 28, 2018 at 18:07

Alex · Accepted Answer · 2018-05-28 18:29:33Z

I think you have some bad design in mind. You can not or I would say that is bad idea to collect objects inside itself especially using coтstructor.

I would suggets you to have either 2 classes

or collect items just in some array outside

or store not the same class but StdClass or array as transaction.

Solution #1:

class Transaction {
  public $fromAddress = "";
  public $toAddress = "";
  public $amount = "";

  public function __construct ($fromAddress, $toAddress, $amount) {
    $this->fromAddress = $fromAddress;
    $this->toAddress = $toAddress;
    $this->amount = $amount;
  }

  public function __toString() {
    return $this->fromAddress . ", " . 
           $this->toAddress . ", " . 
           $this->amount;
  }
}
class TransactionList {
  public $pendingTransactions = [];
  public function __construct ($fromAddress, $toAddress, $amount) {
     $t = new Transaction($fromAddress, $toAddress, $amount);
     $this->pendingTransactions[]=$t;
  }
  public function addTransaction(Transaction $transaction) {
     $this->pendingTransactions[]=$transaction;
  }
}

$tList = new TransactionList('from addr', 'to addr', 'amount');
$tList->addTransaction(new Transaction('from addr 2', 'to addr 2', 'amount2'));
echo ''.$tList->pendingTransactions[1];

Solution #2:

class Transaction {
  public $fromAddress = "";
  public $toAddress = "";
  public $amount = "";

  public function __construct ($fromAddress, $toAddress, $amount) {
    $this->fromAddress = $fromAddress;
    $this->toAddress = $toAddress;
    $this->amount = $amount;
  }
  public function __toString() {
    return $this->fromAddress . ", " . 
       $this->toAddress . ", " . 
       $this->amount;
  }
}
$tList = [];
$tList[] = new Transaction('from addr', 'to addr', 'amount');
$tList[] = new Transaction('from addr 2', 'to addr 2', 'amount2');
echo ''.$tList[1];

Solution #3:

class TransactionList {
  public $pendingTransactions = [];
  public function __construct ($fromAddress, $toAddress, $amount) {
     $this->addTransaction($fromAddress, $toAddress, $amount);
  }
  public function addTransaction($fromAddress, $toAddress, $amount) {
     $t = new StdClass();
     $t->fromAddress = $fromAddress;
     $t->toAddress = $toAddress;
     $t->amount = $amount;
     $this->pendingTransactions[]=$t;
  }
}

$tList = new TransactionList('from addr', 'to addr', 'amount');
$tList->addTransaction('from addr 2', 'to addr 2', 'amount2');
echo ''.$tList->pendingTransactions[1]->toAddress;

Pol Lluis · Accepted Answer · 2018-05-28 17:15:33Z

Hi you can't access that property because if you want to acces an object on your __construct method you need to pass it by parameter first! so you would need something like this:

public function __construct($blockChain)
{
}

Then I understand that you want to set some properties of your object. First you need to understand that in order to populate object properties you must refer to them using $this, on your code you are using $this to point to an object which is not a property of your class, that's why it won't work. For example:

class Transaction {
    public $fromAddress = "";
    public $toAddress = "";
    public $amount = "";
    // here you need to pass the object you want to use when you instantiate the class
    public function __construct ($blockChain)
    { 
       // when using $this you can refer to variables you declared inside your 
       // your class only 
       $this->fromAddress = $blockChain->pendingTransactions[0]->fromAddress
    }
}

I think you should look up some basic theory on how to create objects since it would help you get started. PHP Classes and Objects docs

Collectives™ on Stack Overflow

PHP - set object property within another object's array

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related