CodeIgniter：如何修复两个查询集成时“尝试获取非对象属性”错误

    $this->db->select('*');
    $this->db->from('details');

    if ($country != '')
        {
        $condition .= "(details.service_location IN ('" . $country . "') OR details.country in ('" . $country . "'))";

        }

    $this->db->where($condition);
    $this->db->where('price_range_from >=', $min_price);
    $this->db->where('price_range_to <=', $max_price);
    $this->db->order_by("details.created_on", "asc");
    $query = $this->db->get();

    $results = $query->result();

    foreach ($results as $result)
        {
        $this->db->select('title as image');
        $this->db->from('attachments');
        $this->db->where('parent', $result-id);
        $this->db->where('type', 'job');
        $image = $this->db->get()->row();
        $result->image = $image->image;   // Line No :55

        $this->db->select('sum(feedbacks.rate)/count(feedbacks.rate) as average');
        $this->db->from('feedbacks');
        $this->db->where('parent_id', $result->id);
        $this->db->where('type', 'job');
        $average = $this->db->get()->row();
        $result->average = $average->average;
        $result = (object) $result;
        }

    return $results;
    }

if attachment table doesn't have records it shows an error

Severity: Notice

Message: Trying to get property of non-object

Filename: models/details_model.php

Line Number: 55

$result->image = $image->image;

foreach ($results as $result)
        {
        $this->db->select('title as image');
        $this->db->from('attachments');
        $this->db->where('parent', $result-id);
        $this->db->where('type', 'job');
        $image = $this->db->get()->row();
        if($image){
           $result->image = $image->image;
        }
        $this->db->select('sum(feedbacks.rate)/count(feedbacks.rate) as average');
        $this->db->from('feedbacks');
        $this->db->where('parent_id', $result->id);
        $this->db->where('type', 'job');
        $average = $this->db->get()->row();
        if($average){
           $result->average = $average->average;
        }
        $result = (object) $result;
        }

    return $results;
    }

You defined $results, not $result. tiny difference