Why do errors in external functions within Codeigniter transactions not trigger a rollback?

Codeigniter Transactions

Codeigniter provides a seamless mechanism for handling database transactions through its built-in functions. This allows developers to execute multiple database operations as a single atomic unit of work.

Issue Description

However, when using transactions in Codeigniter, developers may encounter a common issue where errors occurring in external functions called within the transaction block do not trigger a rollback.

External Function Inclusion

To address this issue, it is important to understand that external functions containing database operations should be encapsulated within the model, not the controller. This ensures that the database interactions are executed within the transaction context.

Code Sample with Model-Based Implementation

Consider the following code example:

<code class="php">// Model

class YourModel extends CI_Model {

    public function transactionExample($data, $id) {
        
        $this->db->trans_start();

        $this->db->insert('table_name', $data);

        // Updating data
        $this->db->where('id', $id);
        $this->db->update('table_name', $test); 

        $this->db->trans_complete();

        /*Optional*/

        if ($this->db->trans_status() === FALSE) {
            # Something went wrong.
            $this->db->trans_rollback();
            return FALSE;
        } 
        else {
            # Everything is Perfect. 
            # Committing data to the database.
            $this->db->trans_commit();
            return TRUE;
        }
    }
}</code>

Key Considerations

• By default, Codeigniter runs all transactions in strict mode. When strict mode is enabled, if any group of transactions fails, all groups will be rolled back. If strict mode is disabled, each group is treated independently, meaning a failure in one group will not affect others.
• The trans_complete() function automatically rolls back the transaction if errors occur. Alternatively, developers can manually handle errors using the trans_rollback() and trans_status() functions.

Codeigniter 4 Updates

In Codeigniter 4, the transaction-related function names have changed slightly as follows:

Function	Codeigniter 3	Codeigniter 4
Start Transaction	trans_start()	transBegin()
Complete Transaction	trans_complete()	transCommit()
Rollback Transaction	trans_rollback()	transRollback()
Transaction Status	trans_status()	transStatus()

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