Codeigniter MongoDB类库

安装方法：
1.将mongodb.php 放到config目录
2.将Mongo_db.php放到library目录

使用方法：

$this->mongo_db->where_gte('age', 18)->where(array('country' => 'UK', 'can_drink' => TRUE))->get('people');

代码：

config/mongodb.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

// Generally will be localhost if you're querying from the machine that Mongo is installed on
$config['mongo_host'] = "localhost";

// Generally will be 27017 unless you've configured Mongo otherwise
$config['mongo_port'] = 27017;

// The database you want to work from (required)
$config['mongo_db'] = "";

// Leave blank if Mongo is not running in auth mode
$config['mongo_user'] = "";
$config['mongo_pass'] = "";

// Persistant connections
$config['mongo_persist'] = TRUE;
$config['mongo_persist_key'] = 'ci_mongo_persist';

// Get results as an object instead of an array
$config['mongo_return'] = 'array'; // Set to object

// When you run an insert/update/delete how sure do you want to be that the database has received the query?
// safe = the database has receieved and executed the query
// fysnc = as above + the change has been committed to harddisk <- NOTE: will introduce a performance penalty
$config['mongo_query_safety'] = 'safe';

// Supress connection error password display
$config['mongo_supress_connect_error'] = TRUE;

// If you are having problems connecting try changing this to TRUE
$config['host_db_flag'] = FALSE;

libraries/Mongo_db.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

/**
 * CodeIgniter MongoDB Active Record Library
 *
 * A library to interface with the NoSQL database MongoDB. For more information see http://www.mongodb.org
 * Originally created by Alex Bilbie, but extended and updated by Kyle J. Dye
 *
 * @package        CodeIgniter
 * @author        Alex Bilbie | www.alexbilbie.com | alex@alexbilbie.com
 * @author        Kyle J. Dye | www.kyledye.com | kyle@kyledye.com
 * @copyright    Copyright (c) 2010, Alex Bilbie.
 * @license        http://codeigniter.com/user_guide/license.html
 * @link        http://alexbilbie.com
 * @link        http://kyledye.com
 * @version        Version 0.3.7
 */

class Mongo_db {

    private $CI;
    private $config_file = 'mongodb';

    private $connection;
    private $db;
    private $connection_string;

    private $host;
    private $port;
    private $user;
    private $pass;
    private $dbname;
    private $persist;
    private $persist_key;
    private $query_safety = 'safe';

    private $selects = array();
    public  $wheres = array(); // Public to make debugging easier
    private $sorts = array();

    private $limit = 999999;
    private $offset = 0;

    /**
    *    --------------------------------------------------------------------------------
    *    CONSTRUCTOR
    *    --------------------------------------------------------------------------------
    *
    *    Automatically check if the Mongo PECL extension has been installed/enabled.
    *    Generate the connection string and establish a connection to the MongoDB.
    */

    public function __construct()
    {
        if ( ! class_exists('Mongo'))
        {
            show_error("The MongoDB PECL extension has not been installed or enabled", 500);
        }

        $this->CI =& get_instance();
        $this->connection_string();
        $this->connect();
    }

    /**
    *    --------------------------------------------------------------------------------
    *    Switch_db
    *    --------------------------------------------------------------------------------
    *
    *    Switch from default database to a different db
    */

    public function switch_db($database = '')
    {
        if (empty($database))
        {
            show_error("To switch MongoDB databases, a new database name must be specified", 500);
        }

        $this->dbname = $database;

        try
        {
            $this->db = $this->connection->{$this->dbname};
            return (TRUE);
        }
        catch (Exception $e)
        {
            show_error("Unable to switch Mongo Databases: {$e->getMessage()}", 500);
        }
    }

    /**
    *    --------------------------------------------------------------------------------
    *    Drop_db
    *    --------------------------------------------------------------------------------
    *
    *    Drop a Mongo database
    *    @usage: $this->mongo_db->drop_db("foobar");
    */
    public function drop_db($database = '')
    {
        if (empty($database))
        {
            show_error('Failed to drop MongoDB database because name is empty', 500);
        }

        else
        {
            try
            {
                $this->connection->{$database}->drop();
                return (TRUE);
            }
            catch (Exception $e)
            {
                show_error("Unable to drop Mongo database `{$database}`: {$e->getMessage()}", 500);
            }

        }
    }

    /**
    *    --------------------------------------------------------------------------------
    *    Drop_collection
    *    --------------------------------------------------------------------------------
    *
    *    Drop a Mongo collection
    *    @usage: $this->mongo_db->drop_collection('foo', 'bar');
    */
    public function drop_collection($db = "", $col = "")
    {
        if (empty($db))
        {
            show_error('Failed to drop MongoDB collection because database name is empty', 500);
        }

        if (empty($col))
        {
            show_error('Failed to drop MongoDB collection because collection name is empty', 500);
        }

        else
        {
            try
            {
                $this->connection->{$db}->{$col}->drop();
                return TRUE;
            }
            catch (Exception $e)
            {
                show_error("Unable to drop Mongo collection `{$col}`: {$e->getMessage()}", 500);
            }
        }

        return($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    SELECT FIELDS
    *    --------------------------------------------------------------------------------
    *
    *    Determine which fields to include OR which to exclude during the query process.
    *    Currently, including and excluding at the same time is not available, so the
    *    $includes array will take precedence over the $excludes array.  If you want to
    *    only choose fields to exclude, leave $includes an empty array().
    *
    *    @usage: $this->mongo_db->select(array('foo', 'bar'))->get('foobar');
    */

    public function select($includes = array(), $excludes = array())
    {
         if ( ! is_array($includes))
         {
             $includes = array();
         }

         if ( ! is_array($excludes))
         {
             $excludes = array();
         }

         if ( ! empty($includes))
         {
             foreach ($includes as $col)
             {
                 $this->selects[$col] = 1;
             }
         }
         else
         {
             foreach ($excludes as $col)
             {
                 $this->selects[$col] = 0;
             }
         }
         return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents based on these search parameters.  The $wheres array should
    *    be an associative array with the field as the key and the value as the search
    *    criteria.
    *
    *    @usage : $this->mongo_db->where(array('foo' => 'bar'))->get('foobar');
    */

    public function where($wheres = array())
     {
         foreach ($wheres as $wh => $val)
         {
             $this->wheres[$wh] = $val;
         }
         return ($this);
     }

    /**
    *    --------------------------------------------------------------------------------
    *    OR_WHERE PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field may be something else
    *
    *    @usage : $this->mongo_db->or_where(array( array('foo'=>'bar', 'bar'=>'foo' ))->get('foobar');
    */

    public function or_where($wheres = array())
    {
        if (count($wheres) > 0)
        {
            if ( ! isset($this->wheres['$or']) || ! is_array($this->wheres['$or']))
            {
                $this->wheres['$or'] = array();
            }

            foreach ($wheres as $wh => $val)
            {
                $this->wheres['$or'][] = array($wh=>$val);
            }
        }
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE_IN PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field is in a given $in array().
    *
    *    @usage : $this->mongo_db->where_in('foo', array('bar', 'zoo', 'blah'))->get('foobar');
    */

    public function where_in($field = "", $in = array())
    {
        $this->_where_init($field);
        $this->wheres[$field]['$in'] = $in;
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE_IN_ALL PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field is in all of a given $in array().
    *
    *    @usage : $this->mongo_db->where_in('foo', array('bar', 'zoo', 'blah'))->get('foobar');
    */

    public function where_in_all($field = "", $in = array())
    {
        $this->_where_init($field);
        $this->wheres[$field]['$all'] = $in;
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE_NOT_IN PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field is not in a given $in array().
    *
    *    @usage : $this->mongo_db->where_not_in('foo', array('bar', 'zoo', 'blah'))->get('foobar');
    */

    public function where_not_in($field = "", $in = array())
    {
        $this->_where_init($field);
        $this->wheres[$field]['$nin'] = $in;
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE GREATER THAN PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field is greater than $x
    *
    *    @usage : $this->mongo_db->where_gt('foo', 20);
    */

    public function where_gt($field = "", $x)
    {
        $this->_where_init($field);
        $this->wheres[$field]['$gt'] = $x;
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE GREATER THAN OR EQUAL TO PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field is greater than or equal to $x
    *
    *    @usage : $this->mongo_db->where_gte('foo', 20);
    */

    public function where_gte($field = "", $x)
    {
        $this->_where_init($field);
        $this->wheres[$field]['$gte'] = $x;
        return($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE LESS THAN PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field is less than $x
    *
    *    @usage : $this->mongo_db->where_lt('foo', 20);
    */

    public function where_lt($field = "", $x)
    {
        $this->_where_init($field);
        $this->wheres[$field]['$lt'] = $x;
        return($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE LESS THAN OR EQUAL TO PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field is less than or equal to $x
    *
    *    @usage : $this->mongo_db->where_lte('foo', 20);
    */

    public function where_lte($field = "", $x)
    {
        $this->_where_init($field);
        $this->wheres[$field]['$lte'] = $x;
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE BETWEEN PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field is between $x and $y
    *
    *    @usage : $this->mongo_db->where_between('foo', 20, 30);
    */

    public function where_between($field = "", $x, $y)
    {
        $this->_where_init($field);
        $this->wheres[$field]['$gte'] = $x;
        $this->wheres[$field]['$lte'] = $y;
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE BETWEEN AND NOT EQUAL TO PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field is between but not equal to $x and $y
    *
    *    @usage : $this->mongo_db->where_between_ne('foo', 20, 30);
    */

    public function where_between_ne($field = "", $x, $y)
    {
        $this->_where_init($field);
        $this->wheres[$field]['$gt'] = $x;
        $this->wheres[$field]['$lt'] = $y;
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE NOT EQUAL TO PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the value of a $field is not equal to $x
    *
    *    @usage : $this->mongo_db->where_not_equal('foo', 1)->get('foobar');
    */

    public function where_ne($field = '', $x)
    {
        $this->_where_init($field);
        $this->wheres[$field]['$ne'] = $x;
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE NOT EQUAL TO PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents nearest to an array of coordinates (your collection must have a geospatial index)
    *
    *    @usage : $this->mongo_db->where_near('foo', array('50','50'))->get('foobar');
    */

    function where_near($field = '', $co = array())
    {
        $this->__where_init($field);
        $this->where[$what]['$near'] = $co;
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    LIKE PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents where the (string) value of a $field is like a value. The defaults
    *    allow for a case-insensitive search.
    *
    *    @param $flags
    *    Allows for the typical regular expression flags:
    *        i = case insensitive
    *        m = multiline
    *        x = can contain comments
    *        l = locale
    *        s = dotall, "." matches everything, including newlines
    *        u = match unicode
    *
    *    @param $enable_start_wildcard
    *    If set to anything other than TRUE, a starting line character "^" will be prepended
    *    to the search value, representing only searching for a value at the start of
    *    a new line.
    *
    *    @param $enable_end_wildcard
    *    If set to anything other than TRUE, an ending line character "$" will be appended
    *    to the search value, representing only searching for a value at the end of
    *    a line.
    *
    *    @usage : $this->mongo_db->like('foo', 'bar', 'im', FALSE, TRUE);
    */

    public function like($field = "", $value = "", $flags = "i", $enable_start_wildcard = TRUE, $enable_end_wildcard = TRUE)
     {
         $field = (string) trim($field);
         $this->where_init($field);
         $value = (string) trim($value);
         $value = quotemeta($value);

         if ($enable_start_wildcard !== TRUE)
         {
             $value = "^" . $value;
         }

         if ($enable_end_wildcard !== TRUE)
         {
             $value .= "$";
         }

         $regex = "/$value/$flags";
         $this->wheres[$field] = new MongoRegex($regex);
         return ($this);
     }

    /**
    *    --------------------------------------------------------------------------------
    *    ORDER BY PARAMETERS
    *    --------------------------------------------------------------------------------
    *
    *    Sort the documents based on the parameters passed. To set values to descending order,
    *    you must pass values of either -1, FALSE, 'desc', or 'DESC', else they will be
    *    set to 1 (ASC).
    *
    *    @usage : $this->mongo_db->where_between('foo', 20, 30);
    */

    public function order_by($fields = array())
    {
        foreach ($fields as $col => $val)
        {
            if ($val == -1 || $val === FALSE || strtolower($val) == 'desc')
            {
                $this->sorts[$col] = -1;
            }
            else
            {
                $this->sorts[$col] = 1;
            }
        }
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    LIMIT DOCUMENTS
    *    --------------------------------------------------------------------------------
    *
    *    Limit the result set to $x number of documents
    *
    *    @usage : $this->mongo_db->limit($x);
    */

    public function limit($x = 99999)
    {
        if ($x !== NULL && is_numeric($x) && $x >= 1)
        {
            $this->limit = (int) $x;
        }
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    OFFSET DOCUMENTS
    *    --------------------------------------------------------------------------------
    *
    *    Offset the result set to skip $x number of documents
    *
    *    @usage : $this->mongo_db->offset($x);
    */

    public function offset($x = 0)
    {
        if ($x !== NULL && is_numeric($x) && $x >= 1)
        {
            $this->offset = (int) $x;
        }
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    GET_WHERE
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents based upon the passed parameters
    *
    *    @usage : $this->mongo_db->get_where('foo', array('bar' => 'something'));
    */

    public function get_where($collection = "", $where = array())
    {
        return ($this->where($where)->get($collection));
    }

    /**
    *    --------------------------------------------------------------------------------
    *    GET
    *    --------------------------------------------------------------------------------
    *
    *    Get the documents based upon the passed parameters
    *
    *    @usage : $this->mongo_db->get('foo', array('bar' => 'something'));
    */

     public function get($collection = "")
     {
         if (empty($collection))
         {
             show_error("In order to retreive documents from MongoDB, a collection name must be passed", 500);
         }

         $results = array();

         $documents = $this->db->{$collection}->find($this->wheres, $this->selects)->limit((int) $this->limit)->skip((int) $this->offset)->sort($this->sorts);

         // Clear
         $this->_clear();

         $returns = array();

         foreach ($documents as $doc)
         {
             $returns[] = $doc;
         }

         if ($this->CI->config->item('mongo_return') == 'object')
        {
            return (object)$returns;
        }

        else
        {
            return $returns;
        }

     }

    /**
    *    --------------------------------------------------------------------------------
    *    COUNT
    *    --------------------------------------------------------------------------------
    *
    *    Count the documents based upon the passed parameters
    *
    *    @usage : $this->mongo_db->get('foo');
    */

    public function count($collection = "") {
        if (empty($collection))
        {
            show_error("In order to retreive a count of documents from MongoDB, a collection name must be passed", 500);
        }

        $count = $this->db->{$collection}->find($this->wheres)->limit((int) $this->limit)->skip((int) $this->offset)->count();
        $this->_clear();
        return ($count);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    INSERT
    *    --------------------------------------------------------------------------------
    *
    *    Insert a new document into the passed collection
    *
    *    @usage : $this->mongo_db->insert('foo', $data = array());
    */

    public function insert($collection = "", $insert = array())
    {
        if (empty($collection))
        {
            show_error("No Mongo collection selected to insert into", 500);
        }

        if (count($insert) == 0 || !is_array($insert))
        {
            show_error("Nothing to insert into Mongo collection or insert is not an array", 500);
        }

        try
        {
            $this->db->{$collection}->insert($insert, array($this->query_safety     => TRUE));
            if (isset($insert['_id']))
            {
                return ($insert['_id']);
            }
            else
            {
                return (FALSE);
            }
        }
        catch (MongoCursorException $e)
        {
            show_error("Insert of data into MongoDB failed: {$e->getMessage()}", 500);
        }
    }

    /**
    *    --------------------------------------------------------------------------------
    *    UPDATE
    *    --------------------------------------------------------------------------------
    *
    *    Updates a single document
    *
    *    @usage: $this->mongo_db->update('foo', $data = array());
    */

    public function update($collection = "", $data = array(), $options = array())
    {
        if (empty($collection))
        {
            show_error("No Mongo collection selected to update", 500);
        }

        if (count($data) == 0 || ! is_array($data))
        {
            show_error("Nothing to update in Mongo collection or update is not an array", 500);
        }

        try
        {
            $options = array_merge($options, array($this->query_safety => TRUE, 'multiple' => FALSE));
            $this->db->{$collection}->update($this->wheres, array('$set' => $data), $options);
            $this->_clear();
            return (TRUE);
        }
        catch (MongoCursorException $e)
        {
            show_error("Update of data into MongoDB failed: {$e->getMessage()}", 500);
        }

    }

    /**
    *    --------------------------------------------------------------------------------
    *    UPDATE_ALL
    *    --------------------------------------------------------------------------------
    *
    *    Updates a collection of documents
    *
    *    @usage: $this->mongo_db->update_all('foo', $data = array());
    */

    public function update_all($collection = "", $data = array())
    {
        if (empty($collection))
        {
            show_error("No Mongo collection selected to update", 500);
        }

        if (count($data) == 0 || ! is_array($data))
        {
            show_error("Nothing to update in Mongo collection or update is not an array", 500);
        }

        try
        {
            $this->db->{$collection}->update($this->wheres, array('$set' => $data), array($this->query_safety => TRUE, 'multiple' => TRUE));
            $this->_clear();
            return (TRUE);
        }
        catch (MongoCursorException $e)
        {
            show_error("Update of data into MongoDB failed: {$e->getMessage()}", 500);
        }
    }

    /**
    *    --------------------------------------------------------------------------------
    *    DELETE
    *    --------------------------------------------------------------------------------
    *
    *    delete document from the passed collection based upon certain criteria
    *
    *    @usage : $this->mongo_db->delete('foo', $data = array());
    */

    public function delete($collection = "")
    {
        if (empty($collection))
        {
            show_error("No Mongo collection selected to delete from", 500);
        }

        try
        {
            $this->db->{$collection}->remove($this->wheres, array($this->query_safety => TRUE, 'justOne' => TRUE));
            $this->_clear();
            return (TRUE);
        }
        catch (MongoCursorException $e)
        {
            show_error("Delete of data into MongoDB failed: {$e->getMessage()}", 500);
        }

    }

    /**
    *    --------------------------------------------------------------------------------
    *    DELETE_ALL
    *    --------------------------------------------------------------------------------
    *
    *    Delete all documents from the passed collection based upon certain criteria
    *
    *    @usage : $this->mongo_db->delete_all('foo', $data = array());
    */

     public function delete_all($collection = "")
     {
        if (empty($collection))
        {
            show_error("No Mongo collection selected to delete from", 500);
        }

        try
        {
            $this->db->{$collection}->remove($this->wheres, array($this->query_safety => TRUE, 'justOne' => FALSE));
            $this->_clear();
            return (TRUE);
        }
        catch (MongoCursorException $e)
        {
            show_error("Delete of data into MongoDB failed: {$e->getMessage()}", 500);
        }

    }

    /**
    *    --------------------------------------------------------------------------------
    *    COMMAND
    *    --------------------------------------------------------------------------------
    *
    *    Runs a MongoDB command (such as GeoNear). See the MongoDB documentation for more usage scenarios:
    *    http://dochub.mongodb.org/core/commands
    *
    *    @usage : $this->mongo_db->command(array('geoNear'=>'buildings', 'near'=>array(53.228482, -0.547847), 'num' => 10, 'nearSphere'=>true));
    */

    public function command($query = array())
    {
        try
        {
            $run = $this->db->command($query);
            return $run;
        }

        catch (MongoCursorException $e)
        {
            show_error("MongoDB command failed to execute: {$e->getMessage()}", 500);
        }
    }

    /**
    *    --------------------------------------------------------------------------------
    *    ADD_INDEX
    *    --------------------------------------------------------------------------------
    *
    *    Ensure an index of the keys in a collection with optional parameters. To set values to descending order,
    *    you must pass values of either -1, FALSE, 'desc', or 'DESC', else they will be
    *    set to 1 (ASC).
    *
    *    @usage : $this->mongo_db->add_index($collection, array('first_name' => 'ASC', 'last_name' => -1), array('unique' => TRUE));
    */

    public function add_index($collection = "", $keys = array(), $options = array())
    {
        if (empty($collection))
        {
            show_error("No Mongo collection specified to add index to", 500);
        }

        if (empty($keys) || ! is_array($keys))
        {
            show_error("Index could not be created to MongoDB Collection because no keys were specified", 500);
        }

        foreach ($keys as $col => $val)
        {
            if($val == -1 || $val === FALSE || strtolower($val) == 'desc')
            {
                $keys[$col] = -1;
            }
            else
            {
                $keys[$col] = 1;
            }
        }

        if ($this->db->{$collection}->ensureIndex($keys, $options) == TRUE)
        {
            $this->_clear();
            return ($this);
        }
        else
        {
            show_error("An error occured when trying to add an index to MongoDB Collection", 500);
        }
    }

    /**
    *    --------------------------------------------------------------------------------
    *    REMOVE_INDEX
    *    --------------------------------------------------------------------------------
    *
    *    Remove an index of the keys in a collection. To set values to descending order,
    *    you must pass values of either -1, FALSE, 'desc', or 'DESC', else they will be
    *    set to 1 (ASC).
    *
    *    @usage : $this->mongo_db->remove_index($collection, array('first_name' => 'ASC', 'last_name' => -1));
    */

    public function remove_index($collection = "", $keys = array())
    {
        if (empty($collection))
        {
            show_error("No Mongo collection specified to remove index from", 500);
        }

        if (empty($keys) || ! is_array($keys))
        {
            show_error("Index could not be removed from MongoDB Collection because no keys were specified", 500);
        }

        if ($this->db->{$collection}->deleteIndex($keys, $options) == TRUE)
        {
            $this->_clear();
            return ($this);
        }
        else
        {
            show_error("An error occured when trying to remove an index from MongoDB Collection", 500);
        }
    }

    /**
    *    --------------------------------------------------------------------------------
    *    REMOVE_ALL_INDEXES
    *    --------------------------------------------------------------------------------
    *
    *    Remove all indexes from a collection.
    *
    *    @usage : $this->mongo_db->remove_all_index($collection);
    */

    public function remove_all_indexes($collection = "")
    {
        if (empty($collection))
        {
            show_error("No Mongo collection specified to remove all indexes from", 500);
        }
        $this->db->{$collection}->deleteIndexes();
        $this->_clear();
        return ($this);
    }

    /**
    *    --------------------------------------------------------------------------------
    *    LIST_INDEXES
    *    --------------------------------------------------------------------------------
    *
    *    Lists all indexes in a collection.
    *
    *    @usage : $this->mongo_db->list_indexes($collection);
    */
    public function list_indexes($collection = "")
    {
        if (empty($collection))
        {
            show_error("No Mongo collection specified to remove all indexes from", 500);
        }

        return ($this->db->{$collection}->getIndexInfo());
    }

    /**
    *    --------------------------------------------------------------------------------
    *    CONNECT TO MONGODB
    *    --------------------------------------------------------------------------------
    *
    *    Establish a connection to MongoDB using the connection string generated in
    *    the connection_string() method.  If 'mongo_persist_key' was set to true in the
    *    config file, establish a persistent connection.  We allow for only the 'persist'
    *    option to be set because we want to establish a connection immediately.
    */

    private function connect()
    {
        $options = array();
        if ($this->persist === TRUE)
        {
            $options['persist'] = isset($this->persist_key) && !empty($this->persist_key) ? $this->persist_key : 'ci_mongo_persist';
        }

        try
        {
            $this->connection = new Mongo($this->connection_string, $options);
            $this->db = $this->connection->{$this->dbname};
            return ($this);
        }
        catch (MongoConnectionException $e)
        {
            if($this->CI->config->item('mongo_supress_connect_error'))
            {
                show_error("Unable to connect to MongoDB", 500);
            }
            else
            {
                show_error("Unable to connect to MongoDB: {$e->getMessage()}", 500);
            }
        }
    }

    /**
    *    --------------------------------------------------------------------------------
    *    BUILD CONNECTION STRING
    *    --------------------------------------------------------------------------------
    *
    *    Build the connection string from the config file.
    */

    private function connection_string()
    {
        $this->CI->config->load($this->config_file);

        $this->host    = trim($this->CI->config->item('mongo_host'));
        $this->port = trim($this->CI->config->item('mongo_port'));
        $this->user = trim($this->CI->config->item('mongo_user'));
        $this->pass = trim($this->CI->config->item('mongo_pass'));
        $this->dbname = trim($this->CI->config->item('mongo_db'));
        $this->persist = trim($this->CI->config->item('mongo_persist'));
        $this->persist_key = trim($this->CI->config->item('mongo_persist_key'));
        $this->query_safety = trim($this->CI->config->item('mongo_query_safety'));
        $dbhostflag = (bool)$this->CI->config->item('host_db_flag');

        $connection_string = "mongodb://";

        if (empty($this->host))
        {
            show_error("The Host must be set to connect to MongoDB", 500);
        }

        if (empty($this->dbname))
        {
            show_error("The Database must be set to connect to MongoDB", 500);
        }

        if ( ! empty($this->user) && ! empty($this->pass))
        {
            $connection_string .= "{$this->user}:{$this->pass}@";
        }

        if (isset($this->port) && ! empty($this->port))
        {
            $connection_string .= "{$this->host}:{$this->port}";
        }
        else
        {
            $connection_string .= "{$this->host}";
        }

        if ($dbhostflag === TRUE)
        {
            $this->connection_string = trim($connection_string) . '/' . $this->dbname;
        }

        else
        {
            $this->connection_string = trim($connection_string);
        }
    }

    /**
    *    --------------------------------------------------------------------------------
    *    _clear
    *    --------------------------------------------------------------------------------
    *
    *    Resets the class variables to default settings
    */

    private function _clear()
    {
        $this->selects    = array();
        $this->wheres    = array();
        $this->limit    = 999999;
        $this->offset    = 0;
        $this->sorts    = array();
    }

    /**
    *    --------------------------------------------------------------------------------
    *    WHERE INITIALIZER
    *    --------------------------------------------------------------------------------
    *
    *    Prepares parameters for insertion in $wheres array().
    */

    private function _where_init($param)
    {
        if ( ! isset($this->wheres[$param]))
        {
            $this->wheres[ $param ] = array();
        }
    }

}

// EOF