[TYPO3-english] Correct use of tablenames field in mm tables

[Jigal van Hemert]

Hi,

On 17-6-2011 18:48, Guillermo R. Oramas J. wrote:
> Like an example I have these three tables: customers, suppliers and countries.
[...]
> I understand this:
> The first row means that supplier1 is in germany.
> The second row means that customer1 is also in germany.

Although it can work the column tablenames is usually meant for a 
different situation:

There are three kinds of clients, each has its own table (because some 
fields are different):
- tx_myext_persons
- tx_myext_companies
- tx_myext_organisations

There is also a table of lawyers and you need to store which clients are 
represented by a lawyer:
- tx_myext_lawyers

- tx_myext_mm_lawyers_clients

In this last table lawyer with uid=3 has clients:
- 3 (person), 4 (person)
- 3 (company),
- 5 (organisation)

In tx_myext_mm_lawyers_clients this is stored as:
uid_local | uid_foreign | tablenames
3 | 3 | tx_myext_persons
3 | 4 | tx_myext_persons
3 | 3 | tx_myext_companies
3 | 5 | tx_myext_organisations

So it's a relation of one field with records from more than one table.

> But I already have doubts:
> ¿Is it necessary some TCA configuration in order to TYPO3 understand
> the relations?

Yes, look at the TCA documentation of the 'group' type [1].
internal_type must be 'db'
allowed must list the tables which can be linked 
(tx_myext_persons,tx_myext_companies,tx_myext_organisations)
MM must contain the name of the mm-table

The documentation of the 'select' type [2] also provides good information.

> ¿Is possible to setup it from Kickstarter?

To some extend, yes. If you select 'True MM relations' and select 'all 
tables' for the table you link the data from the kickstarter will set:
allowed => '*',

You can change that later to the desired tables. But at least the 
mm-table is generated, etc.

> ¿Is necessary to set an index for the tablenames field?

If there are loads of relations it can speed up queries.

[1] 
http://typo3.org/documentation/document-library/core-documentation/doc_core_api/4.3.0/view/4/2/#id2525241
[2] 
http://typo3.org/documentation/document-library/core-documentation/doc_core_api/4.3.0/view/4/2/#id2522688

-- 
Kind regards / met vriendelijke groet,

Jigal van Hemert.