Post to facebook page using api with plain php

#webdev #php #facebook #api

If you want to post to your facebook page using api you need to waste few hours or read this short guide.

You should have facebook app. If not - create one.

1. Get Short User Token

Get short user live token here https://developers.facebook.com/tools/explorer. Check permissions: pages_read_engagement and pages_manage_posts

2. Get Forever User Token and save it in .env file

Open https://graph.facebook.com/oauth/access_token?grant_type=fb_exchange_token&client_id=$app_id&client_secret=$app_secret&fb_exchange_token=$short_user_token and get your forever user token (change app_id, app_secret and short_user_token)
You can use browser or some simple func

<?php
function getForeverUserToken(): string
{
    //this values I'm getting from .env file.
    $app_id = config('services.facebook.client_id');
    $app_secret = config('services.facebook.client_secret');
    $short_user_token = config('services.facebook.short_token');

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_URL, "https://graph.facebook.com/oauth/access_token?grant_type=fb_exchange_token&client_id=$app_id&client_secret=$app_secret&fb_exchange_token=$short_user_token");
    $response = curl_exec($ch);
    curl_close($ch);
    if ($response === false) {
        die("Error: " . curl_error($ch));
    }
    $data = json_decode($response, true);
    if (isset($data["error"])) {
        die("Error: " . $data["error"]["message"]);
    }
    return $data["access_token"];
}

3. Post your message

To post to facebook page, we will need Page Access Token. Duration of this token is 60 days, but can be changed anytime. In this example, we generate a new token everytime, but you can save it for some time if you're bulk posting.

<?php
class FacebookPost {

public static function getPageAccessToken(): string
{
    $pageId = config('services.facebook.page_id');
    $forever_user_token = config('services.facebook.admin_token');

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, "https://graph.facebook.com/$pageId?fields=access_token&access_token=$forever_user_token");
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

    $response = curl_exec($ch);

    if ($response === false) {
        die("Error: " . curl_error($ch));
    }
    $data = json_decode($response, true);
    if (isset($data["error"])) {
        die("Error: " . $data["error"]["message"]);
    }
    return $data["access_token"];
}

public static function postMessage(string $message, ?string $link = null): array
{
    $page_token = self::getPageAccessToken();
    $pageId = config('services.facebook.page_id');

    $data = [
        'message' => $message,
        'access_token' => $page_token
    ];
    //if we post link, include it
    if ($link) {
        $data['link'] = $link;
    }

    $ch = curl_init("https://graph.facebook.com/{$pageId}/feed");
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($data));
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $result = curl_exec($ch);
    curl_close($ch);
    return json_decode($result, true);
}
}