PHP致命错误求助：布尔值/字符串上调用成员函数问题排查

Hey there, let's tackle those two fatal errors you're facing in your user_model.php file. I'll break down what's causing each one and show you how to fix them step by step.

Error 1: PHP Fatal error: Call to a member function result() on boolean #

This happens because CodeIgniter's $this->db->query() method returns false when your SQL query fails—common culprits include syntax errors, typos in table/column names, missing database permissions, or malformed query strings. You're trying to call result() on that boolean false value, which isn't allowed.

Quick Fix for Error 1: #

Always validate the query result before calling methods like result():

// Replace your line 46 code with this
$query_result = $this->db->query($query);

// Check if the query executed successfully
if ($query_result !== false) {
    $users = $query_result->result();
    // Proceed with your subscription validation logic here
} else {
    // Debug the error to identify the root cause
    var_dump($this->db->error()); // Shows raw SQL error details
    // For production, log the error instead of dumping it
    log_message('error', 'Package Expire Query Failed: ' . $this->db->error()['message']);
}

Error 2: PHP Fatal error: Call to a member function num_rows() on a string #

This error means you're trying to call num_rows() on a string value instead of a CodeIgniter database result object. The most likely causes are:

• You accidentally assigned a string to the variable you're using num_rows() on (e.g., echoing the query string and reusing it later).
• You're calling num_rows() on $users (an array returned by result()) instead of the original query result object.

Quick Fix for Error 2: #

num_rows() is a method of the query result object, not the array returned by result(). Use it like this:

$query_result = $this->db->query($query);
if ($query_result !== false) {
    $valid_user_count = $query_result->num_rows(); // Correct way to get row count
    $users = $query_result->result(); // This gives you an array of user objects
    // Do NOT call $users->num_rows() — this will throw an error!
}

Additional Debugging & Best Practices #

1. Inspect Your Raw SQL: Print the $query string before execution to catch syntax errors:

   echo $query; // Shows the exact SQL being sent to the database
   die(); // Pause execution to inspect the query
   

   Look for unclosed quotes, missing clauses (like FROM), or typos in table/column names.

2. Use CodeIgniter's Query Builder: Instead of writing raw SQL strings, use the query builder to avoid syntax mistakes and reduce SQL injection risks:

   // Example for your subscription validity check
   $query_result = $this->db->select('*')
                           ->from('customers') // Replace with your actual table name
                           ->where('subscription_end_date <', date('Y-m-d')) // Check expired
                           ->or_where('subscription_status', 'invalid') // Check invalid
                           ->get();
   

3. Verify Database Permissions: Ensure your database user has SELECT access to the table you're querying.

内容的提问来源于stack exchange，提问作者Suraj Sharma