json string to php object via reflection/ like jackson mapper

Question

Im a fan of the jackson mapper in Java, and I'm a bit lost without it in php. I would like an equivalent.

So far the closest I have come across is this, however, it requires the fields to be declared as public, and I dont want to do that:

https://github.com/netresearch/jsonmapper

I want something that does everything that that does, with this sort of code:

<?php
class Contact
{
    /**
     * Full name
     * @var string
     */
    public $name; //<- I want this to be private

    /**
     * @var Address //<- and this
     */
    public $address;
}

class Address
{
    public $street;<- and this
    public $city;<- and this

    public function getGeoCoords()
    {
        //do something with the $street and $city
    }
}

$json = json_decode(file_get_contents('http://example.org/bigbang.json'));
$mapper = new JsonMapper();
$contact = $mapper->map($json, new Contact());

Json from file_get_contents:

{
    'name':'Sheldon Cooper',
    'address': {
        'street': '2311 N. Los Robles Avenue',
        'city': 'Pasadena'
     }
}

So I dont want to be writing individual constructors, or anything individual at all.

Im sure there would be something that does this out of the box using reflection?

Give us a quick idea of what Jackson or "that" does exactly...? — deceze
– deceze ♦, Commented Nov 10, 2015 at 15:34
Jackson will throw the json into java classes like above with private instance variables via reflection with no fuss. — Paul Stanley
– Paul Stanley, Commented Nov 10, 2015 at 15:39

moorscode · Accepted Answer · 2015-11-10 16:27:42Z

This can be achieved very easily and nicely using Closures. There is even no need to create setter functions.

<?php

    class A {
        private $b;
        public $c;

        function d() {

        }
    }

    $data = [
        'b' => 'b-value',
        'c' => 'c-value',
        'd' => 'function',
    ];

    class JsonMapper {
        public function map( $data, $context ) {
            $json_mapper = function() use ( $data ) {
                foreach ($data as $key => $value) {
                    if ( property_exists( $this, $key ) ) {
                        $this->{$key} = $value;
                    }
                }
            };

            $json_mapper = $json_mapper->bindTo( $context, $context );
            $json_mapper();

            return $context;
        }
    }

    $mapper = new JsonMapper();
    $a = $mapper->map( $data, new A );

    print_r($a);

Community · Accepted Answer · 2020-06-20 09:12:55Z

2

You can provide a setter method for protected and private variables:

public function setName($name)
{
    $this->name = $name;
}

JsonMapper will automatically use it.

Since version 1.1.0 JsonMapper supports mapping private and protected properties.

edited Jun 20, 2020 at 9:12

CommunityBot

11 silver badge

answered May 18, 2016 at 7:05

cweiske

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Comments

SheppardDigital · Accepted Answer · 2015-11-10 16:15:39Z

Sorry, I don't have enough 'reputation' so can't add a comment.

I've only been using Java for a few month, but my understanding is that your classes in Java will all have getters and settings, which is how Jackson is able to set the value of a private property.

To do the same in PHP, I suspect you would need to make your properties private, and create getter and setter methods...

public function setName($name) {
    $this->name = name;
}

Then within your Mapper, use reflection to call the setter.

The way I would do this would be to look at the keys you have in the JSON, and try to put together a method name.

For example, if there's a key in the JSON labelled 'name'...

$className = "Contact";
$object = json_decode($jsonResponse);

$classObject = new $className();

foreach ($object as $key => $value) {
    $methodName = "set" . ucfirst($key);

    if (method_exists($classObject, $methodName)) {
        $classObject->$methodName($value);
    }
}

The above may not be exactly right, but I hope it gives you an idea.

To expand on the above, I've put together the following example which seems to do what you require?

class Contact {

    private $name;
    private $telephone;

    public function setName($name) {
        $this->name = $name;
    }

    public function setTelephone($telephone) {
        $this->telephone = $telephone;
    }

    public function getName() {
        return $this->name;
    }

    public function getTelephone() {
        return $this->telephone;
    }

}

class Mapper {

    private $jsonObject;

    public function map($jsonString, $object) {
        $this->jsonObject = json_decode($jsonString);

        if (count($this->jsonObject) > 0) {
            foreach ($this->jsonObject as $key => $value) {
                $methodName = "set" . ucfirst($key);

                if (method_exists($object, $methodName)) {
                    $object->$methodName($value);
                }
            }
        }

        return $object;
    }

}

$myContact = new stdClass();
$myContact->name = "John Doe";
$myContact->telephone = "0123 123 1234";

$jsonString = json_encode($myContact);

$mapper = new Mapper();
$contact = $mapper->map($jsonString, new Contact());

echo "Name: " . $contact->getName() . "<br>";
echo "Telephone: " . $contact->getTelephone();

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