优化将参数从控制器传递到模型以进行mysql查询的方式

Question

I am working on a project in condeigniter(newbie). My project include listing of products using different filters like categories, subcategories, keywords, minimum-maximum prices etc. I have done this hundred of times in custom php, where i make variable $where for all conditions in where clause. For example

$where = '';
if($category != '')
{
  $where .= " category = '$category'";
}

Now in codeigniter I have multiple paramters,which I can get in my controller through uri segment and call model function, pass all parameters and run mysql query there. The problem is I am checking every parameter if it is empty or set and run multiple queries accordingly. For example.

if($category != '' && $subCategory != '')
{
  //whole query here
}
else  if($category == '' && $subCategory != '')
{
  //whole query here
}

//and so on

What I need is any optimize way of doing this, as I have joins (multiple paramters).

My sample conditions and queries

if($subCat == '' && $vendor == '')
    {
        $cat = str_replace("-"," ",str_replace("-and-"," & ",$cat));
        $this->db->select('listings.* ');
        $this->db->from('listings');
        $this->db->join('categories','categories.id = listings.category');
        $this->db->where('categories.name',$cat);
        $this->db->limit($perpage,$page);
        $query = $this->db->get();
        return $query->result();
    }
    else if($subCat == '' && $vendor != '')
    {
        $cat = str_replace("-"," ",str_replace("-and-"," & ",$cat));
        $this->db->select('listings.* ');
        $this->db->from('listings');
        $this->db->join('categories','categories.id = listings.category');
        $this->db->join('vendors','vendors.id = listings.programme');
        $this->db->where('categories.name',$cat);
        $this->db->where('vendors.name',$vendor);
        $this->db->limit($perpage,$page);
        $query = $this->db->get();
        return $query->result();
    }
    else if($subCat != '' && $vendor == '')
    {
        $cat = str_replace("-"," ",str_replace("-and-"," & ",$cat));
        $this->db->select('listings.* ');
        $this->db->from('listings');
        $this->db->join('categories','categories.id = listings.category');
        $this->db->join('subcategories','subcategories.id = listings.subcategory');
        $this->db->where('categories.name',$cat);
        $this->db->where('subcategories.name',$subCat);
        $this->db->limit($perpage,$page);
        $query = $this->db->get();
        return $query->result();
    }
    else
    {
        $cat = str_replace("-"," ",str_replace("-and-"," & ",$cat));
        $subCat = str_replace("-"," ",str_replace("-and-"," & ",$subCat));
        $vendor = str_replace("-"," ",str_replace("-and-"," & ",$vendor));

        $this->db->select('listings.* ');
        $this->db->from('listings');
        $this->db->join('categories','categories.id = listings.category');
        $this->db->join('subcategories','subcategories.id = listings.subcategory');
        $this->db->join('vendors','vendors.id = listings.programme');
        $this->db->where('categories.name',$cat);
        $this->db->where('subcategories.name',$subCat);
        $this->db->where('vendors.name',$vendor);
        $this->db->limit($perpage,$page);
        $query = $this->db->get();  
        return $query->result();
    }

Answer 1

You need to write the query once only and not every time. For example you may have several conditions as you have described. For example, here is something what I have done:

$this->db->select('resource.id,city.name as city_name,city.provinceID,resource.Rate, skills.name')->from('resource')
->join('city','resource.cityID = city.id')
->join('resourceToSkillsMap','resource.id = resourceToSkillsMap.resourceID')
->join('skills','skills.id =  resourceToSkillsMap.skillsID');

if($category != '' && $subCategory != '') #condition
{
    $this->db->where('condition');
}
else  if($category == '' && $subCategory != '') #condition
{
    $this->db->where('condition');
}

$rs = $this->db->group_by('resource.id')
->limit($limit,$offset)
->get();

See how the query is written only once but the where condition is given inside the if else . SO your query will be build up that way. After the query is executed just echo $this->db->last_query(); to echo the query and adjust it as you want it.

Answer 2

In your helper you can construct your $where array() like this

$where = array();
if($category != '')
{
   $where['category'] = $category;
} else {
   $where['someotherkey'] = 'someothervalue';
}

And in your controller you just pass the $where array while calling the model.

$this->foo_model->foo_method($where);

And in model you can do something like this

$this->db->where($where);

EDIT

if($category != '')
{
   //Along with your $this->db->where()
   $this->db->join('table1','condition1');
} else {
   //Along with your $this->db->where()
   $this->db->join('table2','condition2');
}

To Tidy Up things

$cat = str_replace("-"," ",str_replace("-and-"," & ",$cat));
$this->db->select('listings.* ');
$this->db->from('listings');
$this->db->join('categories','categories.id = listings.category');  
$this->db->where('categories.name',$cat);

if($vendor != '')      {
  $this->db->join('vendors','vendors.id = listings.programme');
  $this->db->where('vendors.name',$vendor);
}
if($subCat != ''){
  $subCat = str_replace("-"," ",str_replace("-and-"," & ",$subCat));
  $this->db->join('subcategories','subcategories.id = listings.subcategory');
  $this->db->where('subcategories.name',$subCat);
}    

$this->db->limit($perpage,$page);
$query = $this->db->get();
return $query->result();