How to check if value is empty in PHP [JSON]

Question

I have some JSON parameters, that I want to validate if the value are empty with an IF statement. I have written an IF statement in a function to check, but the IF statement only checks for the parameter, I want to check for the values if they are empty. Please, how do I go about this. my code

   //api.php

    $payment_type = $this->validateParameter('payment_type', $this->param['payment_type'], STRING, true);

$date_of_delivery = $this->validateParameter('date_of_delivery', $this->param['date_of_delivery'], STRING, true);

 $your_generated_waybill_number = $this->validateParameter('your_generated_waybill_number', $this->param['your_generated_waybill_number'], STRING, true);


   "payment_type" - is an example of parameter ||  "1" - is an example of value



     {
  "name":"create_insert_new_delivery",
  "param":{
       "payment_type":"1",
       "date_of_delivery":"", //E.g here want to check if the value is empty
       "your_generated_waybill_number":"39ei40909444567avaab",
       }
    }





  //rest.php
   public function validateParameter($fieldName, $value, $required = true){

    if($required == true && empty($value) == true){
        $this->throwError(EMPTY_PARAMETER, $fieldName . " parameter is missing"); //HERE check if the parameter is missing and fires error, but I also want to include value check
    } else if ($required == true && empty($fieldName) == true){
        $this->throwError(API_PARAM_REQUIRED, $fieldName . " value is required");
    } else {

    } //check when parameter is present but value is empty and leave if it is not required

  }

Did you see, your method is 3 args while you're calling it with 4 ? And did you see you assign their calls in variables while the method have no return ? — WizardNx, Jun 22 '18 at 18:37

Andrei Todorut · Answer 1 · 2018-06-22T20:55:55.380

3

With empty() function you check for the value

$str = '';
// or 
$str = null;
// or 
$str = false;
var_dump(empty($str)) // output => true

To check if a variable is defined you can use isset

http://php.net/manual/ro/function.isset.php

edited Jun 22 '18 at 20:55

answered Jun 22 '18 at 18:25

Andrei Todorut

4,260
2
17
28

score 3 · Answer 2 · answered Jun 22 '18 at 18:31

3

testing your variable should be done by using the identity operator.

if (!$var){}

or

if  ($var === null){} //checks by type

or

if (empty($field)){}

answered Jun 22 '18 at 18:31

bitsNbytes

64
6

score 2 · Accepted Answer · answered Jun 22 '18 at 18:31

You may make your function a little clearer since the tests you are doing will already return true or false. There is no need to compare them to true.

if ($required AND empty($value)) {
        $this->throwError(EMPTY_PARAMETER, $fieldName . " parameter is missing"); //HERE check if the parameter is missing and fires error, but I also want to include value check
    } elseif ($required AND empty($fieldName)) {
        $this->throwError(API_PARAM_REQUIRED, $fieldName . " is required");
    } elseif (!empty($fieldName) AND empty($value)) {
        $this->throwError(API_PARAM_REQUIRED, $fieldName . " value is required");
    }
}

Dan · Answer 4 · 2018-06-22T18:53:49.670

You're main problem is that you're passing the value (grabbed from the array) to the method and checking that. Because at that point, if the array key is not set, a warning is triggered and the value is coerced to null.

empty(): Will return true when the variable is not set OR if it evaluates to some falsey value (e.g. false, null, [], "", etc)

isset(): Will return true ONLY if the value is not set.

So:

$a = ['one' => false];
empty($a['one']); //true
isset($a['one']); //true
isset($a['two']); //false

So you could edit you validation function like so:

public function validateParameter($fieldName, &$inputArray, $required = true){

    if($required){
        if(!isset($inputArray[$fieldName])){
            $this->throwError(EMPTY_PARAMETER, $fieldName . " parameter is missing");
        } else if (empty($inputArray[$fieldName])){
            $this->throwError(API_PARAM_REQUIRED, $fieldName . " value is required");
        }
    } else {
        if(!isset($inputArray[$fieldName])){
            return null;
        }
    }

    return $inputArray[$fieldName];
  }

Note: since you are checking a class attribute $this->param. You may avoid passing the array to the method and just reference $this->param in the function, unless it should be more reusable.

I didn't completely understand you desired result in the missing block, but made a reasonable assumption

How to check if value is empty in PHP [JSON]

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