A pretty basic but effective class that can be used to do CRUD operations on Microsoft Dynamics NAV's Odata service for the customer entity

dynamics.odata.services.php

<?php

// A pretty basic but effective class that can be used for doing CRUD operations on Microsoft Dynamics NAV's Odata services

error_reporting(E_ALL);
ini_set("display_errors", 1);

class http_request {

    protected $_handle = NULL;
    protected $_credentials = '';
    protected $_url = '';
    protected $_service = '';
    protected $_company = '';
    protected $_suffix = '';
    protected $_requestType = '';
    protected $_header = [
        'Connection: Keep-Alive',
        'Accept: application/json',
        'Content-Type: application/json; charset=utf-8',
        'DataServiceVersion: 3.0',
        'MaxDataServiceVersion: 3.0',
        'Prefer: return-content',
        "Accept: */*"
    ];

    protected function _ifMatch($header, $etag) {
        array_push($header, 'If-Match: W/"\'' . $etag . '\'"');
        return $header;
    }

    protected function _setData($data) {
        if (!empty($data)) {
            if (count($data) === 1) {
                if (is_array($data[0])) {
                    $this->_suffix = $this->_buildSuffix(NULL, $data[0]);
                } else {
                    $this->_suffix = $this->_buildSuffix($data[0], NULL);
                }
            } else {
                $this->_suffix = $this->_buildSuffix($data[0], $data[1]);
            }
        } else {
            $this->_suffix = $this->_buildSuffix(NULL, NULL);
        }
    }

    protected function _buildCompanySuffix() {
        if ($this->_company === NULL) {
            return '';
        }
        return 'Company(\'' . $this->_company . '\')/';
    }

    protected function _buildIDSuffix($id = NULL) {
        if ($id === NULL) {
            return '';
        }
        return '(\'' . $id . '\')';
    }

    protected function _buildQuerySuffix($fields = NULL) {
        if ($fields === NULL) {
            return '';
        }
        if ($this->_requestType === 'GET') {
            $this->setOption('postfields', '');
            return '?' . urldecode(http_build_query(['$select' => implode(',', $fields)]));
        } elseif ($this->_requestType === 'DELETE') {
            $this->setOption('postfields', '');
            return '';
        } else {
            $this->setOption('postfields', json_encode($fields));
            return '';
        }
    }

    protected function _buildSuffix($id, $q) {
        return $this->_buildCompanySuffix() . $this->_service . $this->_buildIDSuffix($id) . $this->_buildQuerySuffix($q);
    }

    protected function _setRequestType($requestType, $data) {
        $this->_requestType = $requestType;
        $this->_suffix = '';
        $this->_setData($data);
        switch ($requestType) {
            case 'GET':
            case 'POST':
                $this->setOptions([
                    'customrequest' => $requestType,
                    'post' => ($requestType === 'POST'),
                    'url' => $this->_url . $this->_suffix,
                    'httpheader' => $this->_header
                ]);
                break;
            case 'PATCH':
            case 'DELETE':
                $this->setOptions([
                    'customrequest' => $requestType,
                    'post' => true,
                    'url' => $this->_url . $this->_suffix,
                    'httpheader' => $this->_ifMatch($this->_header, $data[1]["ETag"])
                ]);
                break;
            default:
            // DO NOTHING YET
        }
    }

    protected function _initService($provider = [], $options = []) {
        if(!is_array($provider)) {
            $provider = json_decode(file_get_contents($provider), true);
        }
        if (isset($provider['url']) && $provider['url'] !== '') {
            $this->setProvider($provider['url']);
        }
        if (isset($provider['credentials']) && $provider['credentials'] !== '') {
            $this->setCredentials($provider['credentials']);
        }
        if (isset($options['service']) && $options['service'] !== '') {
            $this->setService($options['service']);
        }
        if (isset($options['company']) && $options['company'] !== '') {
            $this->setCompany($options['company']);
        }
        $this->_handle = curl_init();
        $this->setOptions([
            'returntransfer' => true,
            'userpwd' => $this->_credentials
        ]);
    }

    protected function _send() {
        return json_decode(curl_exec($this->_handle), TRUE);
    }

    public static function factory($provider = [], $options = []) {
        return new static($provider, $options);
    }

    public function __construct($provider = [], $options = []) {
        $this->_initService($provider, $options);
    }

    public function create($data) {
        $this->_setRequestType('POST', [$data]);
        return $this->_send();
    }

    public function read() {
        $this->_setRequestType('GET', func_get_args());
        return $this->_send();
    }

    public function update($id, $data) {
        $olddata = $this->read($id, ['No', 'ETag']);
        $data['No'] = $olddata['No'];
        $data['ETag'] = $olddata['ETag'];
        $this->_setRequestType('PATCH', [$id, $data]);
        return $this->_send();
    }

    public function delete($id) {
        $olddata = $this->read($id, ['No', 'ETag']);
        $this->_setRequestType('DELETE', [$id, $olddata]);
        return $this->_send();
    }

    public function setProvider($url) {
        $this->_url = $url;
    }

    public function setCredentials($credentials = '') {
        $this->_credentials = $credentials;
    }

    public function setService($service = '') {
        $this->_service = $service;
    }

    public function setCompany($company = '') {
        $this->_company = $company;
    }

    public function setOption($key, $value) {
        curl_setopt($this->_handle, constant("CURLOPT_" . strtoupper($key)), $value);
        return $this;
    }

    public function setOptions($options) {
        foreach ($options as $key => $value) {
            $this->setOption($key, $value);
        }
        return $this;
    }

    public function __destruct() {
        // Close handle
        curl_close($this->_handle);
    }
}

/* HOW TO USE : */
/* ------------ */

/* Create an instance */
$service = http_request::factory([
    "url" => "https://<Server>:<WebServicePort>/<ServerInstance>/OData/",
    "credentials" => "username:password"
], [
    'company' => 'My company',
    'service' => 'customer'
]);


/* GET a list of customers */
echo json_encode($service->read(), JSON_PRETTY_PRINT);


/* READ the values for customer 14 */
echo json_encode($service->read(14), JSON_PRETTY_PRINT);


/* CREATE a new customer */
echo json_encode($service->create([
    "Name" => "A test customer",
    "Address" => "Times Square",
    ...
]), JSON_PRETTY_PRINT);


/* UPDATE the customer with ID 15 */
echo json_encode($service->update(13, [
    "Name" => "PX Automatics",
    "Phone_No" => "+32 56 48 88 68",
]), JSON_PRETTY_PRINT);


/* DELETE the customer with ID 15 */
echo json_encode($service->delete(15), JSON_PRETTY_PRINT);

Herebelow is an overview of how to do the same, using plain cURL requests...

---

Read

$ch = curl_init(); 

curl_setopt($ch, CURLOPT_URL, 'https://<Server>:<WebServicePort>/<ServerInstance>/OData/Company(\'<CompanyName>\')/customer(\'1\')'); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);   
curl_setopt($ch, CURLOPT_POST, false);  

curl_setopt($ch, CURLOPT_USERPWD, 'username:password');   
curl_setopt($ch, CURLOPT_HTTPHEADER, [
        'Accept: application/json',          
        'Content-Type: application/json; charset=utf-8',
]);   

$response = json_decode(curl_exec($ch), TRUE);
echo json_encode($response, JSON_PRETTY_PRINT);
// Close handle
curl_close($ch);

Write

$ch = curl_init(); 

curl_setopt($ch, CURLOPT_URL, 'https://<Server>:<WebServicePort>/<ServerInstance>/OData/Company(\'<CompanyName>\')/customer'); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);   
curl_setopt($ch, CURLOPT_POST, true);  

curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode([
    "Name" => "This is a test customer",
    ...
]));

curl_setopt($ch, CURLOPT_USERPWD, 'username:password');   
curl_setopt($ch, CURLOPT_HTTPHEADER, [
        'Accept: application/json',          
        'Content-Type: application/json; charset=utf-8',
]);   

$response = json_decode(curl_exec($ch), TRUE);
echo json_encode($response, JSON_PRETTY_PRINT);
curl_close($ch);

Update

$ch = curl_init(); 

curl_setopt($ch, CURLOPT_URL, 'https://<Server>:<WebServicePort>/<ServerInstance>/OData/Company(\'<CompanyName>\')/customer(\'1\')'); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);   
curl_setopt($ch, CURLOPT_POST, true);  
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'PATCH');

curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode([
    "Name" => "This is a test customer",
    ...
]));

curl_setopt($ch, CURLOPT_USERPWD, 'username:password');   
curl_setopt($ch, CURLOPT_HTTPHEADER, [
        'Accept: application/json',          
        'Content-Type: application/json; charset=utf-8',
        'If-Match: W/"\'' .  $etag . '\'"',
        // You can get your etag value by doing a get request first
        // In the class hereabove, you don't need to worry about this, as the class takes care of this
]);   

$response = json_decode(curl_exec($ch), TRUE);
echo json_encode($response, JSON_PRETTY_PRINT);
curl_close($ch);

Delete

$ch = curl_init(); 

curl_setopt($ch, CURLOPT_URL, 'https://<Server>:<WebServicePort>/<ServerInstance>/OData/Company(\'<CompanyName>\')/customer(\'1\')'); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);   
curl_setopt($ch, CURLOPT_POST, true);  
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'DELETE');

curl_setopt($ch, CURLOPT_USERPWD, 'username:password');   
curl_setopt($ch, CURLOPT_HTTPHEADER, [
        'Accept: application/json',          
        'Content-Type: application/json; charset=utf-8',
        'If-Match: W/"\'' .  $etag . '\'"',
        // You can get your etag value by doing a get request first
        // In the class hereabove, you don't need to worry about this, as the class takes care of this
]);   

$response = json_decode(curl_exec($ch), TRUE);
echo json_encode($response, JSON_PRETTY_PRINT);
curl_close($ch);