How to Troubleshoot the 'invalid_grant' Error When Refreshing Google Analytics API Access Tokens?

Refreshing Access Tokens with Google API Client

When interacting with the Google Analytics API (V3), it's crucial to handle token expiration to maintain access to data. The Google API Client provides a refreshToken() method to obtain a new access token using a refresh token. However, you may encounter an "invalid_grant" error while attempting to use this method.

Understanding Token Expiration

An access token has a limited lifespan, typically an hour. After the token expires, a new access token must be obtained. The refreshToken() method can be used to retrieve a new access token.

Debugging the "invalid_grant" Error

The "invalid_grant" error indicates that the refresh token being used is invalid or has expired. To troubleshoot this issue, verify the following:

• Ensure that you are using the correct refresh token associated with the expired access token.
• Check that the refresh token has not expired (its lifespan is approximately 6 months).

Code Example

Below is a simplified example that demonstrates how to refresh an access token and store it in a database:

<?php
use Google\Client;
use Google\Service\Analytics;

// Set up your client and credentials
$client = new Client();
$client->setClientId('YOUR_CLIENT_ID');
$client->setClientSecret('YOUR_CLIENT_SECRET');
$client->setRedirectUri('YOUR_REDIRECT_URI');
$client->setScopes('https://www.googleapis.com/auth/analytics.readonly');
$client->setState('offline');

// Retrieve the original access token (with a refresh token) from your database
$original_access_token = json_decode($token, true);
$refresh_token = $original_access_token['refresh_token'];

// Check if the original access token has expired
$time_created = $original_access_token['created'];
$time_now = time();
$time_diff = $time_now - $time_created;

// Refresh the access token if it has expired
if ($time_diff > 3600) {
    // Check if a refresh token exists in the database
    $refresh_token_query = "SELECT * FROM token WHERE type='refresh'";
    $refresh_token_result = mysqli_query($cxn, $refresh_token_query);

    // If a refresh token exists, use it to get a new access token
    if ($refresh_token_result != 0) {
        $refresh_token_row = mysqli_fetch_array($refresh_token_result);
        $refresh_token_created = json_decode($refresh_token_row['token'], true)['created'];
        $refresh_token_time_diff = $time_now - $refresh_token_created;

        // If the refresh token has expired, update it
        if ($refresh_token_time_diff > 3600) {
            $client->refreshToken($refresh_token);
            $new_access_token = $client->getAccessToken();

            // Update the refresh token in the database
            $refresh_token_update_query = "UPDATE token SET token='$new_access_token' WHERE type='refresh'";
            mysqli_query($cxn, $refresh_token_update_query);

            // Update the original access token in the database
            $original_access_token_update_query = "UPDATE token SET token='$new_access_token' WHERE type='original'";
            mysqli_query($cxn, $original_access_token_update_query);
        } else {
            // Use the existing refresh token to get a new access token
            $client->refreshToken($refresh_token);
            $new_access_token = $client->getAccessToken();

            // Update the original access token in the database
            $original_access_token_update_query = "UPDATE token SET token='$new_access_token' WHERE type='original'";
            mysqli_query($cxn, $original_access_token_update_query);
        }
    } else {
        // If a refresh token does not exist, retrieve a new one
        $client->refreshToken($refresh_token);
        $new_access_token = $client->getAccessToken();

        // Insert the new refresh token into the database
        $refresh_token_insert_query = "INSERT INTO token (type, token) VALUES ('refresh', '$new_access_token')";
        mysqli_query($cxn, $refresh_token_insert_query);

        // Update the original access token in the database
        $original_access_token_update_query = "UPDATE token SET token='$new_access_token' WHERE type='original'";
        mysqli_query($cxn, $original_access_token_update_query);
    }
}

// Use the new or refreshed access token to make API calls
$service = new Analytics($client);

The above is the detailed content of How to Troubleshoot the 'invalid_grant' Error When Refreshing Google Analytics API Access Tokens?. For more information, please follow other related articles on the PHP Chinese website!