PHP: Codeigniter migrating snake_case column names to camelCase column names.

XXX_camel_tables.php

<?php

//this migration demonstrates a potential migration that changes snake case column names to camelcase names
//the reverse is in the down function

class Migration_camel_tables extends CI_Migration {

	public function up(){
		
		$tables = $this->db->list_tables();
		
		foreach($tables as $table){
		
			//need to detect if it's a session table, if it is, don't change it (due to its nativeness!)
			if($table == $this->config->item('sess_table_name')){
				continue;
			}		
			
			$field_data = $this->db->field_data($table);
			
			$changes = '';
			
			foreach($field_data as $field){
			
				//change the field name, and keep the field type
				$changes[$field->name] = array(
					'name'	=> strtolower($field->name[0]).substr(str_replace(' ', '', ucwords(preg_replace('/[\s_]+/', ' ', $field->name))), 1),
					'type'	=> $field->type,
				);
				
				//add in a constraint if it exists
				if($field->max_length !== null){
					$changes[$field->name] += array(
						'constraint'	=> $field->max_length,
					);
				}
				
				//if the field is not id, and the field's default is not null, we want to keep it
				if($field->name !== 'id' AND $field->default !== null){
					if($field->type !== 'timestamp'){
						$changes[$field->name] += array(
							'default'	=> $field->default,
						);
					}
				}
				
				//make sure ids are auto incremented and not null
				if($field->name === 'id'){
					$changes[$field->name] += array(
						'auto_increment'	=> true,
						'null'				=> false,
					);
				}
				
			}
			
			$this->dbforge->modify_column($table, $changes);
			
		}

	}

	public function down(){	
	
		$tables = $this->db->list_tables();
		
		foreach($tables as $table){
		
			//need to detect if it's a session table, if it is, don't change it (due to its nativeness!)
			if($table == $this->config->item('sess_table_name')){
				continue;
			}
			
			$field_data = $this->db->field_data($table);
			
			$changes = '';
			
			foreach($field_data as $field){
			
				//change the field name to snake case, and keep the field type
				$changes[$field->name] = array(
					'name'	=> strtolower(preg_replace('/([a-z])([A-Z])/', '$1_$2', $field->name)),
					'type'	=> $field->type,
				);
				
				//add in a constraint if it exists
				if($field->max_length !== null){
					$changes[$field->name] += array(
						'constraint'	=> $field->max_length,
					);
				}
				
				//if the field is not id, and the field's default is not null, we want to keep it
				if($field->name !== 'id' AND $field->default !== null){
					if($field->type !== 'timestamp'){
						$changes[$field->name] += array(
							'default'	=> $field->default,
						);
					}
				}
				
				//make sure ids are auto incremented and not null
				if($field->name === 'id'){
					$changes[$field->name] += array(
						'auto_increment'	=> true,
						'null'				=> false,
					);
				}
				
			}
			
			$this->dbforge->modify_column($table, $changes);
			
		}
	
	}
}