Question

Class Account extends CI_Model {
    private $tbl_rest   = array();
    private $tbl_fields = array('bs_id', 'bs_name', 'bs_type', 'bs_sub');

    function get_data($dataid){
        $this->db->select( '*' );
        $this->db->from( $this->tbl_name );
        $this->db->where( $this->tbl_key, $id );

        $query  = $this->db->get(); 
        if( $query->num_rows() > 0 ) 
        {
            foreach ($query->result() as $row)
            {
                $this->tbl_rest[] .= '<li id="'.$row->bs_id.'">'.$row->bs_name.'</li>';
            }

            echo( json_encode( array( 'tdata' => $this->tbl_rest ) ) );
        } else {
            echo( false );
        }
    }
}

When I change $query->result() like this

'<li id="'.$row->$this->tbl_fields[0].'">'.$row->$this->tbl_fields[1].'</li>';

I starting getting error “Object of class could not be converted to string”
My Question is:

1. Is possible to convert an array string to object?

2. And how to make $row->$this->tbl_fields[0] happen, so I do not always have to write the name of the field.

Answer 1

This is a basic order of operations issue. PHP doesn’t know if you want some dynamic $this property of the row, or the $this->tbl_fields[0] property of the row.

Try this:

<?php
 $this->tbl_rest[] .= '<li id="'.$row->{$this->tbl_fields[0]}.'">'.$row->{$this->tbl_fields[1]}.'</li>';

Additionally, I would recommend defining the model’s $tbl_fields property as either static or constant, as it doesn’t change at run-time or for specific instances of the class:

<?php
Class Account extends CI_Model {
    private static $tbl_fields = array('bs_id', 'bs_name', 'bs_type', 'bs_sub');
    // ...

    $this->tbl_rest[] .= '<li id="'.$row->{self::$tbl_fields[0]}.'">'.$row->{self::$tbl_fields[1]}.'</li>';

    // ...
}

Furthermore, hard-coding array references to specific column names is somewhat counter-productive, unless you know that [0] will always be the ID, and [1] will always be the name (in which case, you might as well set a static prefix for the column names and use that instead of the $tbl_fields array).

Better yet, because all you’re doing here is a key/value pair (I assume you want to re-use this pattern for other API methods…), you could simply select the fields the way you want to use them. Here’s what I would recommend:

<?php
Class Account extends CI_Model {
    private $tbl_rest   = array();
    private static $col_prefix = 'bs_';

    function get_data($dataid){
        $this->db->select(array(
            self::$col_prefix.'id AS key',
            self::$col_prefix.'name AS value'
        ));
        $this->db->from( $this->tbl_name );
        $this->db->where( $this->tbl_key, $id );

        $query  = $this->db->get(); 
        if( $query->num_rows() > 0 ) 
        {
            foreach ($query->result() as $row)
            {
                $this->tbl_rest[] .= '<li id="'.$row->key.'">'.$row->value.'</li>';
            }

            echo( json_encode( array( 'tdata' => $this->tbl_rest ) ) );
        } else {
            echo( false );
        }
    }
}