[TYPO3-mvc] Casting objects

[Xavier Perseguers]

Hi Jochen,

>>> I am going to implement another feature (one of the last ones before
>>> feature freeze) which enables you to say
>>>
>>> $query = $this->queryFactory->create($className());
>>> $query->setStatement('SELECT ... FROM (SELECT ... FROM ... WHERE ...)');
>>> $objects = $query->execute();
>>
>> Great! But did you rewrite the SQL parser from TYPO3? I guess no, this
>> means that such statements won't be able to be passed to DBAL.
> 
> I have written an SQL parser (see 
> Tx_Extbase_Persistence_Storage_Typo3DbBackend). It translates the 
> generic Query Object Model into (hopefully) valid SQL. After that, It 
> invokes $GLOBALS['TYPO3_DB]->sql_query($sqlString).

Funny, method sql_query() are deprecated in DBAL, XCLASS of t3lib_db. 
But the main method in t3lib_db is not deprecated.

> Does that work for your use case?

Unfortunately not as it only works for _DEFAULT handler in DBAL, which 
mean the handler that is used by TYPO3 itself, it does not work for 
other handlers. And the problem is that I use MySQL for TYPO3 itself and 
MSSQL to access data from a legacy database. Meaning I have two handlers 
and _DEFAULT is the MySQL one.

Moreover, I know why sql_query is deprecated in DBAL, this is because 
the query is not processed at all, it is sent as this to the DBMS but in 
case of Oracle for instance (in another project that runs 100% on 
Oracle), I had to use mapping methods of DBAL which allow table and 
column names to be rewritten on the fly when communicating with the 
database, while TYPO3, or the ext that issued the query is not aware of 
this transformation. This is needed because there is a limit of 30 
characters for identifiers in Oracle, meaning standard tables from 
TemplaVoilà are not compatible with Oracle. When you use sql_query, the 
SQL parser is not used and the query cannot be rewritten to update field 
and table names...

-- 
Xavier Perseguers
DBAL-Member

http://xavier.perseguers.ch/en/tutorials/typo3.html