Read nested json in php - php

Question

I know others have already asked about this, but I don't find a solution for my problem. In my PHP page I call an external service and I can't modify the response obtained.
I'm moving my first steps both with JSON and PHP.
The response is a JSON like this, I print this using the var_dump method:
object(stdClass)#1 (3)
{
["search_string"]=>string(15) "ABCDEFG HI LMNO"
["resut"]=>string(5) "apixi"
["0"]=>array(1){
[0]=>object(stdClass)#2(2){
["resp_code"]=>string(7) "12.34.0"
["resp_description"]=>string(15) "ABCDEFG HI LMNO"
}
}
}
In my PHP page I can read the value ”ABCDEFG HI LMNO” for the key "search_string" with this code, in the $output variable I store the result of the cUrl call
.......
$output = curl_exec($ch);
$jsonDecode =json_decode(str_replace('""','"',$output));
var_dump($jsonDecode);
echo $jsonDecode -> search_string;
I need the str_replace method because the JSON is dirty but not always, how can I access at the fields "resp_code" and "resp_description" and then store them in a variable? I tried many solutions but none works for me.

Answer 1

Instead of converting JSON array to stdClass object you can also convert it to regular PHP array by adding second parameter to the json_decode function:
$jsonDecode =json_decode(str_replace('""','"',$output), true);
In your case in the output, you'll get a multidimensional array.
Then, to access resp_code and resp_description, you can do something like this:
$respCode = $jsonDecode[0]["resp_code"];
$respDescription = $jsonDecode[0]["resp_description"];

Answer 2

In the decoded JSON you have, the resp_code and resp_description keys are difficult to get to, because the top-level object has a numerical ("0") attribute. Trying to reach that attribute like this:
$jsonDecode -> 0
will give this parsing error:
syntax error, unexpected '0' (T_LNUMBER), expecting identifier (T_STRING) or variable (T_VARIABLE) or '{' or '$'
Trying the same with a string notation (-> "0") also fails.
However, the suggestion in the error message is useful: encapsulate the zero with braces. Then you can proceed easily by adding the array index selector ([0]) to get to the object and keys of your interest, like this:
echo $jsonDecode->{0}[0]->resp_code;
echo $jsonDecode->{0}[0]->resp_description;
If you expect more elements in that array $jsonDecode->{0}, then loop over them like this:
foreach ($jsonDecode->{0} as $element) {
echo $element->resp_code;
echo $element->resp_description;
}
Alternative
If, however, you prefer to work with associative arrays instead of objects, you can use the second argument of json_encode as stated in the docs:
assoc
When TRUE, returned objects will be converted into associative arrays.
So then you would pass true as second argument:
$jsonDecode = json_decode(str_replace('""', '"', $output), true);
The above code would then be rewritten like this to access the variable as an associative array:
foreach ($jsonDecode[0] as $element) {
echo $element["resp_code"];
echo $element["resp_description"];
}