Extract Data From JSON in PHP

Extract Data From JSON in PHP

Minahil Noor Dec-10, 2020 Sep-29, 2020 PHP PHP JSON

In this article, we will introduce methods to extract data from JSON in PHP.

  • Using json_decode() function

Use json_decode() Function to Extract Data From JSON in PHP

We will use the built-in function json_decode() to extract data from JSON. We will convert the JSON string to an object or an array to extract the data. The correct syntax to use this function is as follows.

json_decode($jsonString, $assoc, $depth, $options);

The built-in function json_decode() has four parameters. The details of its parameters are as follows

Parameters Description
$jsonString mandatory It is the JSON encoded string from which we want to extract the data.
$assoc optional It is a Boolean variable. If it is TRUE, the function will return an associative array. If FALSE, the function will return the object.
$depth optional It is an integer. It specifies the specified depth.
$options optional It specifies the bitmask of JSON_BIGINT_AS_STRING, JSON_INVALID_UTF8_IGNORE, JSON_INVALID_UTF8_SUBSTITUTE, JSON_OBJECT_AS_ARRAY, JSON_THROW_ON_ERROR. You can check their details here.

This function returns NULL if the JSON string is not in a proper format. It returns an associative array or object depending upon the $assoc parameter.

The program below shows how we can use the json_decode() function to extract data from a JSON string.

<?php 
$jsonString ='{
    "firstName":"Olivia",
    "lastName":"Mason",
    "dateOfBirth":
    {
        "year":"1999",
        "month":"06",
        "day":"19"
    }
}';
$data = json_decode($jsonString);
echo("The data is: \n");
var_dump($data);
?> 
    

The function will return an object because we have not passed the $assoc parameter.

Output:

The data is: 
object(stdClass)#1 (3) {
  ["firstName"]=>
  string(6) "Olivia"
  ["lastName"]=>
  string(5) "Mason"
  ["dateOfBirth"]=>
  object(stdClass)#2 (3) {
    ["year"]=>
    string(4) "1999"
    ["month"]=>
    string(2) "06"
    ["day"]=>
    string(2) "19"
  }
}

If we pass the $assoc parameter, the function will return an associative array.

<?php 
$jsonString ='{
    "firstName":"Olivia",
    "lastName":"Mason",
    "dateOfBirth":
    {
        "year":"1999",
        "month":"06",
        "day":"19"
    }
}';
$data = json_decode($jsonString, true);
echo("The data is: \n");
var_dump($data);
?> 

Output:

The data is: 
array(3) {
  ["firstName"]=>
  string(6) "Olivia"
  ["lastName"]=>
  string(5) "Mason"
  ["dateOfBirth"]=>
  array(3) {
    ["year"]=>
    string(4) "1999"
    ["month"]=>
    string(2) "06"
    ["day"]=>
    string(2) "19"
  }
}

If the function has returned an object, we can access the data in the following way:

<?php 
$jsonString ='{
    "firstName":"Olivia",
    "lastName":"Mason",
    "dateOfBirth":
    {
        "year":"1999",
        "month":"06",
        "day":"19"
    }
}';
$data = json_decode($jsonString);
echo("The first name is: \n");
echo $data->firstName;
?> 

The function will return the first name from the data extracted.

Output:

The first name is: 
Olivia

If the function has returned an array, we can directly access the data in the following way:

<?php 
$jsonString ='{
    "firstName":"Olivia",
    "lastName":"Mason",
    "dateOfBirth":
    {
        "year":"1999",
        "month":"06",
        "day":"19"
    }
}';
$data = json_decode($jsonString, true);
echo("The first name is: \n");
echo $data['firstName'];
?> 

The function will return the first name from the data extracted.

Output:

The first name is: 
Olivia

We can also iterate through our array.

<?php 
$jsonString ='{
    "firstName":"Olivia",
    "lastName":"Mason",
    "dateOfBirth": "19-09-1999"
}';
$data = json_decode($jsonString, true);
foreach ($data as $key=> $data1) {
    echo $key, " : ";
    echo $data1, "\n";
}
?> 

The function will return the extracted data.

Output:

firstName : Olivia
lastName : Mason
dateOfBirth : 19-09-1999

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