Why Am I Getting a 'Fatal Error: fetch_assoc() on a Non-Object' in My PHP Database Queries?

Fatal Error: fetch_assoc() on a Non-Object

When executing database queries, you may encounter the following error message:

Fatal error: Call to a member function fetch_assoc() on a non-object

This error occurs when the fetch_assoc() method is called on a non-object, typically a mysqli_result object.

Problem Analysis:

In the provided code snippet, you may have written a function like the following:

function get_recent_highs(...){
    $result = $this->database->query($query);
    while($row = $result->fetch_assoc()) {...}
}

If $result is a non-object, the fetch_assoc() call will fail. This can occur if there is an error in the SQL query, which causes query() to return false instead of a result object.

Solution:

To resolve the error, check the return value of query(). If it returns false, throw an exception or handle the error accordingly. For instance:

function get_recent_highs(...){
    $result = $this->database->query($query);
    if (!$result) {
        throw new Exception("Database Error");
    }
    while($row = $result->fetch_assoc()) {...}
}

By catching the error in query(), you can ensure that fetch_assoc() is only called on a valid result object, preventing the non-object error.

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