Php object access data

How to extract and access JSON data in PHP

JavaScript Object Notation(JSON) is a lightweight human-readable text format for storing and transporting data consisting of name-value pairs and arrays.

It is easy to generate and parse in many programming languages. It is the most popular and lightweight data-interchange format for web applications and the de-facto format for the data exchange in RESTful web services requests and responses.

In this post, we will cover how to decode a JSON object and access its data in PHP.

Below is an example of a simple JSON object:

How to receive JSON data in PHP

1. From a POST or GET request

To receive JSON data as a POST request, we use the “php://input” along with the function file_get_contents() as below:

For instance, the JSON data is sent below as a POST request:

'; $curl = curl_init(); curl_setopt($curl, CURLOPT_URL, $url); curl_setopt($curl, CURLOPT_HTTPHEADER, array('Content-Type:application/json')); curl_setopt($curl, CURLOPT_RETURNTRANSFER, true); curl_setopt($curl, CURLOPT_POST, true); curl_setopt($curl, CURLOPT_POSTFIELDS, $payload); curl_exec($curl); curl_close($curl); 

To receive the above request data in the register.php file, just add file_get_contents(«php://input») and assign it to a variable for processing eg:

2. Reading a JSON file

A JSON file contains a JSON object and has a file extension of .json. You can as well open the file in PHP and access its data.

Similar to POST or GET request, we use file_get_contents() but instead of having “php://input”, we use the file path.

For example, if we have a JSON file with path «https://www.example.com/mydata.json«, we can access its data as below:

If the json file and the PHP file accessing it are in the same website, we can use relative path instead of the full file URL.

Extracting/Decoding JSON data in PHP

We use the built-in function json_decode() to convert the JSON string to the appropriate data type such as an object or an array.

1. Accessing JSON data as a PHP object

By default the json_decode() function returns an object.

Example
The example below decodes a JSON object into a PHP object:

'; $data = json_decode($json); var_dump($data); 

The above example outputs below:

object(stdClass)#1 (4) < ["firstName"]=>string(4) «John» [«lastName»]=> string(3) «Doe» [«email»]=> string(17) «johndoe@gmail.com» [«phone»]=> string(12) «111-111-1111» >

To access the PHP object data, you use the object operator (->) after the object name, followed by the key of the key-value pair. This is the same as the name in the name-value pair in JSON object eg $data->firstName .

'; $data = json_decode($json); echo "My name is".$data->firstName." ".$data->lastName; //Output: My name is John Doe 

2. Accessing JSON data as an array

You can as well convert the JSON object to a PHP associative array by passing a second(optional) parameter in the json_decode() function with the boolean value «true» as below. The value is set to false by default if you don’t pass it.

The example below decodes JSON object into a PHP associative array:

'; $data = json_decode($json, true); var_dump($data); 

The above example outputs below:

array(4) < ["firstName"]=>string(4) «John» [«lastName»]=> string(3) «Doe» [«email»]=> string(17) «johndoe@gmail.com» [«phone»]=> string(12) «111-111-1111» >

You access the data as in any other PHP associative array as in the example below:

'; $data = json_decode($json, true); echo "My name is ".$data["firstName"]." ".$data["lastName"]; //Output: My name is John Doe 

3. Accessing data in a nested JSON object

A JSON object may comprise of json objects and arrays as the values in its name-value pairs such as in the example below:

In the above example, the «address» has an object as its value while «siblings» has an array value comprising of objects.

The easiest way of accessing all the data is decoding the object as an associative array.

, "siblings": [ < "name": "Joseph Doe" >, < "name": "Mary Doe" >] >'; $data = json_decode($json, true); //Displaying all the data echo "First Name: ".$data["firstName"]."
"; //Output -> First Name: John echo "First Name: ".$data["lastName"]."
"; //Output -> Last Name: Doe echo "Email Address: ".$data["email"]."
"; //Output -> Email Address: johndoe@gmail.com echo "Postal Address: ".$data["address"]["postalAddress"]."
"; //Output -> Postal Address: 12345 echo "Postal Code: ".$data["address"]["postalCode"]."
"; //Output -> Postal Code: 5432 echo "City: ".$data["address"]["city"]."
"; //Output -> City: Nairobi echo "Sibling 1: ".$data["siblings"][0]["name"]."
"; //Output -> Sibling 1: Joseph Doe echo "Sibling 2: ".$data["siblings"][1]["name"]."
"; //Output -> Sibling 2: Mary Doe 

Looping through an object of objects with foreach()

You may have a large JSON object made of an array of objects, like in the example below:

To access the values of a country in the example above, you just have to know its object position in the array. For example, china is in the third position. But when accessing the array items, we start counting from 0, hence the index of China in the array is 2.

We access the China array object as below:

"; //Output -> Country: China echo "Code: ".$data["countries"][2]["code"]."
"; //Output -> Code: CN echo "City: ".$data["countries"][2]["city"]."
"; //Output -> City: Beijing 

If you want to access all the array data then it can be tiresome and time-consuming to write the code for accessing each at a time especially when the object is large. For such an instance, you can use the foreach() function to loop through all the objects as below:

, < "name": "India", "code": "IN", "city": "New Delhi" >, < "name": "China", "code": "CN", "city": "Beijing" >, < "name": "Germany", "code": "DE", "city": "Berlin" >, < "name": "Kenya", "code": "KE", "city": "Nairobi" >] >'; $countries = json_decode($json)->countries; foreach($countries as $country)< echo "Country: ".$country->name."
"; echo "Code: ".$country->code."
"; echo "City: ".$country->city."
"; > 

Conclusion

In this post, we have covered everything you need to know in extracting and accessing a JSON object data using PHP.

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A simple PHP DAO/Controller Framework

Disclaimer: I am no PHP expert and I’m happy about all suggestions for improvement. Aim I wanted a really simple and easy to use framework to quickly create a simple backend in PHP that can easily be deployed just using copy&paste to a managed webserver that runs PHP and a MySQL database (as most of the cheaper hosted services). Therefore I created a set of base classes in PHP that automatically provide the CRUD operations using reflection. It’s then easy to concentrate on a nice frontend using Angular, React, etc. This is no OR-mapping functionality, therefore the schema on the database has to be created manually. Entities The entities (the data objects) are simple PHP classes. They must have an $id field and a constructor accepting all fields is needed. To be able to serialize them as JSON objects, they have to implement the JsonSerializable interface. In the jsonSerialize method, all the object properties are returned via the get_object_vars method.

class User implements JsonSerializable  private $id; private $firstName; private $lastName; function __construct($id, $firstName, $lastName)  $this->id = $id; $this->firstName = $firstName; . > public function getId()  . > public function setId($id)  . > // all getters / setters for the other properties public function jsonSerialize()  return (object) get_object_vars($this); > > 

Data Access Objects For every entity, there is a data access object. It derives from GenericDao and creates the basic CRUD operations using reflection. The SQL queries are created dynamically and are then processed via plain PDO. For example, to find all entities, a simple SELECT * FROM query is created and the result is automatically mapped to an entity, so that, for example, instances of the class User are returned. Therefore a DAO class has to be created that overrides the getEntityClass method:

class UserDao extends GenericDao  protected function getEntityClass()  return 'User'; > > 

public function findAll()  $query = "SELECT * FROM ".strtolower($this->getEntityClass()).";"; $stmt = $this->dbh->prepare($query); if ($stmt->execute())  $result = []; while ($row = $stmt->fetch())  array_push($result, $this->mapToEntity($row)); > return $result; > return []; > 

The other methods for create, update and delete work in a similar way. For create and update also the fields of the entity are needed. This is done using the ReflectionClass class.

$this->reflection = new ReflectionClass($this->getEntityClass()); $properties = $this->reflection->getProperties(ReflectionProperty::IS_PRIVATE); return $properties; 

• Request method GET and url parameter ?findAll calls dao->findAll
• Request method GET and url parameter ?findById=1 returns the entity with (by calling dao->findById )
• Request method PUT and url parameter ?save calls dao->insert . The entity has to be sent in the request body as json object.
• Request method PUT and url parameter ?update calls dao->update . Again, the entity has to be in the request body.
• Request method DELETE and url parameter ?delete=1 calls dao->delete and deletes the entity with id 1.

Continuing the User example, the controller would look like this:

header('Content-type: application/json'); $controller = new EntityController(new UserDao()); $controller->handleRequests(); 

The controller can then be called by url like this: http://www.mydomain.com/api/userController.php?findAll

Of course this is not the most secure, powerful or even efficient way to do it, but it provides you with the basic CRUD operations out of the box so that you can focus on the user interface and your business logic without having to waste time on this standard stuff.

It is still work-in-progress and any feedback is welcome. As written at the beginning, my main aim is to have a simple framework that does not need much configuration and can easily used simply by copy&paste, without having to install any additional tools.

I hope this maybe helps somebody, even though it is just for learning 🙂

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