Select only calculated columns in Propel

Question

I'm trying to perform a selection with Propel which returns only calculated columns, but I allways have other columns selected.

For example:

$criteria = new MuestraQuery();
$criteria->clearSelectColumns()
    ->addAsColumn('numEspesores', 'count(distinct muestra.sal_espesor)')

Resulting query:

 SELECT muestra.sal_id, muestra.sal_regimen, 
        -- ...
        -- (ALL FIELDS OF THE TABLE HERE...)
        -- ...
        count(distinct muestra.sal_espesor) AS numEspesores 
 FROM muestra

I've been able to reduce the number of fields selected including only a field. For example, this query returns only two fields:

$criteria = new MuestraQuery();
$criteria->clearSelectColumns()
    ->select(MuestraTableMap::COL_SAL_ID)
    ->addAsColumn('numEspesores', 'count(distinct muestra.sal_espesor)')

Resulting query:

SELECT count(distinct muestra.sal_espesor) AS numEspesores,
       muestra.sal_id AS "muestra.sal_id" 
FROM muestra

¿Is there a way in Propel to select only computed columns?

I've seen columns are added in ModelCriteria->doSelect() based on protected ModelCriteria->isSelfSelected property, which is set in ModelCriteria->select() but not in addAsColumn() because it's from Criteria and it's not overriden in ModelCriteria.

Don't know if this is a bug or I'm doing something badly.

Answer 1

Just select the computed column that you added.

MuestraQuery::create()
    ->select(['numEspesores'])
    ->addAsColumn('numEspesores', 'count(distinct muestra.sal_espesor)')
    ->find();

Due to Propel's fluent api, you do not have to call the select method prior to the addAsColumn method, so you could even do the following:

MuestraQuery::create()
    ->addAsColumn('numEspesores', 'count(distinct muestra.sal_espesor)')
    ->select(['numEsesores'])
    ->find();