lib/Doctrine/MongoDB/Aggregation/Stage/Project.php
public function excludeFields(array $fields)
    {
        foreach ($fields as $fieldName) {
            $this->field($fieldName)->expression(false);
        }

        return $this;
    }
public function excludeFields(array $fields)
    {
        foreach ($fields as $fieldName) {
            $this->field($fieldName)->expression(false);
        }

        return $this;
    }
public function excludeFields ( array $ fields ) { foreach ( $ fields as $ fieldName ) { $ this -> field ( $ fieldName ) -> expression ( false ) ; } return $ this ; }
Shorthand method to define which fields to be excluded.

If you specify the exclusion of a field other than _id, you cannot employ
any other $project specification forms.

@since 1.5
@param array $fields
@return $this
Shorthand method to define which fields to be excluded .