Answer by j0k for Select One column Doctrine DQL

This is because Doctrine hydrate the response with all the object information, so all columns.

You need to use a different hydration method, there are many one, but let's focus on 5 of them:

• HYDRATE_RECORD, the default one
• HYDRATE_ARRAY
• HYDRATE_NONE
• HYDRATE_SCALAR
• HYDRATE_ARRAY_SHALLOW

You need the HYDRATE_ARRAY_SHALLOW hydration method. Here's why.

1. HYDRATE_RECORD

   $q = Doctrine_Query::create()    ->select('a.pro_id')    ->from('fndr_proyecto a')    ->where('a.pro_id = ?',1);$pro = $q->execute(array(), Doctrine_Core::HYDRATE_RECORD);var_dump(json_encode($pro->toArray()));

   This will hydrate the result using object, and also hydrate relations (if you use a leftJoin inside your query). Since it returns object, we need to call toArray() to be able to send a propre json:

   [{"id":1,"name":"Project name","year":2013}]"

2. HYDRATE_ARRAY

   $q = Doctrine_Query::create()    ->select('a.pro_id')    ->from('fndr_proyecto a')    ->where('a.pro_id = ?',1);$pro = $q->execute(array(), Doctrine_Core::HYDRATE_ARRAY);var_dump(json_encode($pro));

   This will hydrate result as an array an automatically add the primary key:

   [{"id":"1","pro_id":"1"}]"

3. HYDRATE_NONE

   $q = Doctrine_Query::create()    ->select('a.pro_id')    ->from('fndr_proyecto a')    ->where('a.pro_id = ?',1);$pro = $q->execute(array(), Doctrine_Core::HYDRATE_NONE);var_dump(json_encode($pro));

   This won't hydrate result, and return just values:

   [["1"]]"

4. HYDRATE_SCALAR

   $q = Doctrine_Query::create()    ->select('a.pro_id')    ->from('fndr_proyecto a')    ->where('a.pro_id = ?',1);$pro = $q->execute(array(), Doctrine_Core::HYDRATE_SCALAR);var_dump(json_encode($pro));

   This will hydrate result from the select but with key index as the column name with the table alias:

   [{"a_pro_id":"1"}]"

5. HYDRATE_ARRAY_SHALLOW

   $q = Doctrine_Query::create()    ->select('a.pro_id')    ->from('fndr_proyecto a')    ->where('a.pro_id = ?',1);$pro = $q->execute(array(), Doctrine_Core::HYDRATE_ARRAY_SHALLOW);var_dump(json_encode($pro));

   This will hydrate result from the select but with key index as the column name without the table alias:

   "[{"pro_id":"1"}]"