[Lazarus] WebData

[Leonardo M. Ramé]

On 2010-10-15 14:24:48 +0200, Michael Van Canneyt wrote:
> >After removing the TSqlQuery and TSQLTransaction components from my app,
> >a new question came to my mind, in the case of complex inserts/updates
> >that involves more than one database table, is it possible to use
> >transactions?.
> 
> Hm. Not if you use the TSQLDBWebDataProvider. To do that, you would
> have to use TSQLSuery and a regular TWebDataProvider, and hook into
> the Before/after post events of the TSQLQuery.
> 
> But I'm certainly open for suggestions for improvements.
> 
> Michael.

Well, It's not an issue at all, I could create a stored procedure in
charge of receiveing the params from the dataprovider, then adapt them to 
their respective tables. It's not an issue because I usually work with
Firebird and PostgreSql, and they have stored procedures.

I ask this because I'm thinking of adding a new layer of abstraction by
letting the TFPWebProviderDataModule load a configuration from, say, an
XML file with the list of Providers and its Select, Insert, Update, and
Delete statements, like this:

<Module name="ClientesProvider">
  <Provider name="all-customers">
    <Select>select * from customers</Select>
  </Provider>
  <Provider name="one-customer">
    <Select>
      select * from customers where IdCustomer=:IdCustomer
    </Select>
    <Insert>
      insert into customers(Name, Age) 
      values(:Name, :Age)
    </Insert>
    <Update>
      update customers set Name=:Name, Age=:Age
      where IdCustomer=:IdCustomer
    </Update>
    <Delete>
      delete from customers where IdCustomer=:IdCustomer
    </Delete>
  </Provider>
</Module>

With this data, the cgi/fcgi app could dynamically create the
TPWebProviderDataModule and everything else.

What do you think about this?

-- 
Leonardo M. Ramé
http://leonardorame.blogspot.com