Json 键值与否？

Question

i want to know json particular key has value or not

please check my below json :

[{"highest_education":"B.E ( Automobile Engineering )","occupation":"Job in Private Office","annual_income":""}]

in this json i want to check annual_income has value or not in PHP

i dont want json_decode() and check every value it is not good solution

Answer 1

解码后首先解码json ，您将获得数组，然后使用条件检查特定值

 json_decode($myObj);

Answer 2

To check annual_income has value or not. You have to first convert your json data into array. like below code.

$yourArray = json_encode($yourArray,true);

once your json will convert into array than u will check annual_income has value or not.

if(!empty($yourArray[0]['annual_income']) && $yourArray[0]['annual_income'] != ''){
  // Not empty
}

Answer 3

Well, I disagree that json_decode() has poor performance; I'll show you the proof below.

To achieve your task, you can use the following codes:

$json_string = '[{"highest_education":"B.E ( Automobile Engineering )","occupation":"Job in Private Office","annual_income":""}]';
$json_array = json_decode($json_string, true);
if(isset($json_array['annual_income']) && !empty($json_array['annual_income'])) {
    // value is not null
} else {
    // value is null or empty
}

There is no need to iterate through the JSON array at all.

Using PHP 7.1.16, I ran both methods for 1000 times, the performance difference between strpos() and json_decode() is not significant.

json_decode() used: 0.001691s
strpos() used: 0.00033s

Full test code is here: https://pastebin.com/ZcpjydfK , you can test it on your computer.

On the other side, there is a problem using strpos() approach. There is a chance that the JSON string is malformed, or space is added between the colon : , then your strpos() checking won't work.

Answer 4

it is not good way to json_decode() and check every key it is to much lengthy and make execution speed low

i got the right answer

$annual_income1='"annual_income":""';
$annual_income2='"annual_income":null';    
if(strpos($json,$annual_income1) !== false || strpos($json,$annual_income2) !== false){ 
echo "annual_income key is empty";
}