CakePHP: How can I use a “HAVING” operation when building queries with find method?

问题

I'm trying to use the "HAVING" clause in a SQL query using the CakePHP paginate() method.

After some searching around it looks like this can't be achieved through Cake's paginate()/find() methods.

The code I have looks something like this:

$this->paginate = array(
        'fields' => $fields,
        'conditions' => $conditions,
        'recursive' => 1,
        'limit' => 10, 
        'order' => $order,
        'group' => 'Venue.id');

One of the $fields is an alias "distance". I want to add a query for when distance < 25 (e.g. HAVING distance < 25).

I have seen two workarounds so far, unfortunately neither suit my needs. The two I've seen are:

1) Adding the HAVING clause in the "group" option. e.g. 'group' => 'Venue.id HAVING distance < 25'. This doesn't seem to work when used in conjunction with pagination as it messes up the initial count query that is performed. (ie tries to SELECT distinct(Venue.id HAVING distance < 25) which is obviously invalid syntax.

2) Adding the HAVING clause after the WHERE condition (e.g. WHERE 1 = 1 HAVING field > 25) This doesn't work as it seems the HAVING clause must come after the group statement which Cake is placing after the WHERE condition in the query it generates.

Does anyone know of a way to do this with CakePHP's find() method? I don't want to use query() as that would involve a lot of rework and also mean I'd need to implement my own pagination logic!

Thanks in advance

回答1:

You have to put it with the group conditions. like this

$this->find('all', array(
    'conditions' => array(
        'Post.length >=' => 100
    ),
    'fields' => array(
        'Author.id', 'COUNT(*) as Total'
    ),
    'group' => array(
        'Total HAVING Total > 10'
    )
));

Hope it helps you

回答2:

I used the following trick to add my own HAVING clause at the end of my WHERE clause. The "dbo->expression()" method is mentioned in the cake sub-query documentation.

function addHaving(array $existingConditions, $havingClause) {
  $model = 'User';
  $db = $this->$model->getDataSource();

  // Two fun things at play here,
  // 1 - mysql doesn't allow you to use aliases in WHERE clause
  // 2 - Cake doesn't allow a HAVING clause separate from a GROUP BY
  // This expression should go last in the WHERE clause (following the last AND)
  $taut = count($existingConditions) > 0 ? '1 = 1' : '';
  $having = $db->expression("$taut HAVING $havingClause");

  $existingConditions[] = $having;

  return $existingConditions;
}

回答3:

As per the manual, CakePHP/2 supports having at last. It was added as find array parameter on version 2.10.0, released on 22^nd July 2017.

From the 2.10 Migration Guide:

Model::find() now supports having and lock options that enable you to add HAVING and FOR UPDATE locking clauses to your find operations.

回答4:

Just had the same problem. I know, one is not supposed to modify the internal code but if you open the PaginatorComponent and you modify line 188:

$count = $object->find('count', array_merge($parameters, $extra));

to this:

$count = $object->find(
             'count', 
             array_merge(array("fields" => $fields),$parameters, $extra)
         );

Everything will be fixed. You will be able to add your HAVING clause to the 'group' and the COUNT(*) won't be a problem.

Or, make line:

$count = $object->paginateCount($conditions, $recursive, $extra);

to include the $fields:

$count = $object->paginateCount($fields,$conditions, $recursive, $extra);

After that, you can "override" the method on the Model and make sure to include the $fields in the find() and that's it!, =P

回答5:

Here is another idea that doesn't solve the pagination issue, but it is clean since it just overrides the find command in AppModel. Just add a group and having element to your query and this will convert to a HAVING clause.

public function find($type = 'first', $query = array()) {
    if (!empty($query['having']) && is_array($query['having']) && !empty($query['group'])) {
      if ($type == 'all') {
        if (!is_array($query['group'])) {
          $query['group'] = array($query['group']);
        }

        $ds = $this->getDataSource();
        $having = $ds->conditions($query['having'], true, false);
        $query['group'][count($query['group']) - 1] .= " HAVING $having";

        CakeLog::write('debug', 'Model->find: out query=' . print_r($query, true));
      } else {
        unset($query['having']);
      }
    }

    return parent::find($type, $query);
  }

Found it here

https://groups.google.com/forum/?fromgroups=#!topic/tickets-cakephp/EYFxihwb55I

来源：https://stackoverflow.com/questions/7747656/cakephp-how-can-i-use-a-having-operation-when-building-queries-with-find-meth

标签

mysql

cakephp

cakephp-2.x