Php, using a count in an array

Question

I am trying create an invoice using Xero accounting software's API (php). I can create an invoice and add the products without any issues if I use the below code (excerpt):

$lineitem1 = new XeroAPI\XeroPHP\Models\Accounting\LineItem;
$lineitem1
->setItemCode(MODEL-REF1)
->setQuantity(10)
->setTaxType(NONE);
$arr_lineitem = [];
array_push($arr_lineitem, $lineitem1);

$lineitem2 = new XeroAPI\XeroPHP\Models\Accounting\LineItem;
$lineitem2
->setItemCode(MODEL-REF2)
->setQuantity(20)
->setTaxType(NONE);   
$arr_lineitem = [];
array_push($arr_lineitem, $lineitem2);

This works without any issues and will create two products on the invoice (MODEL-REF1 and MODEL-REF2) with their associated quantities and tax types.

The problem starts when I try to populate these details from a form from the previous page (since there could be 1 or 100+ different products on each invoice). The form will pass on the products model item code etc with a unique id (auto incrementing by 1 shown by"X" in the example below) and will also pass on the total amount of product lines purchased.

e.g. the form for the above would be:

<input type="text" id="ItemCode**X**" name="ItemCode**X**" value="MODEL-REF1">
<input type="text" id="Quantity**X**" name="Quantity**X**" value="10">
<input type="text" id="TaxType**X**" name="TaxType**X**" value="NONE">

<input type="text" id="ItemCode**X**" name="ItemCode**X**" value="MODEL-REF2">
<input type="text" id="Quantity**X**" name="Quantity**X**" value="20">
<input type="text" id="TaxType**X**" name="TaxType**X**" value="NONE">

<input type="text" id="TotalProductsInLoop" name="TotalProductsInLoop" value="2">

As such, I thought I could then loop through the values as follows on the script API side (and in turn submit the products to xero) using the below:

for ($i=1; $i<=$TotalProductsInLoop; $i++) {
   
    $ItemCode = $_POST['ItemCode'.$i];
    $Quantity = $_POST['Quantity'.$i];
    $TaxType = $_POST['TaxType'.$i];

    $lineitem . $i = new XeroAPI\XeroPHP\Models\Accounting\LineItem;
    $lineitem . $i
    ->setItemCode($ItemCode)
    ->setQuantity($Quantity)
    ->setTaxType($TaxType);
    
    $arr_lineitem = [];
    array_push($arr_lineitem, $lineitem . $i);
    
}

However, this just submits the last product in the loop e.g. MODEL-REF2 and not the first product of the others to the invoice.

Can any one see what I'm missing here?

I'm assuming it's something to do with using a counting loop in an array??

Answer 1

1. I highly doubt that the following lines execute without any warnings or errors:

    $lineitem . $i = new XeroAPI\XeroPHP\Models\Accounting\LineItem;
    $lineitem . $i
    ->setItemCode($ItemCode)
    ->setQuantity($Quantity)
    ->setTaxType($TaxType);

This ($lineitem . $i) is standard string concatenation, numbered variables cannot be created like this.

In fact, you do not need numbered variables, you can reuse a single variable in the loop.

2. You are resetting the result container array ($arr_lineitem) in every loop step. So it always will contain only the latest value.

The correct code should look more like this:

$arr_lineitem = [];
for ($i=1; $i<=$TotalProductsInLoop; $i++) {
   
    $ItemCode = $_POST['ItemCode'.$i];
    $Quantity = $_POST['Quantity'.$i];
    $TaxType = $_POST['TaxType'.$i];

    $lineitem = new XeroAPI\XeroPHP\Models\Accounting\LineItem;
    $lineitem
    ->setItemCode($ItemCode)
    ->setQuantity($Quantity)
    ->setTaxType($TaxType);
    
    array_push($arr_lineitem, $lineitem);
}