H1 2015 - db access support in Phobos

[Vadim Lopatin via Digitalmars-d]

On Tuesday, 3 February 2015 at 10:49:07 UTC, Robert burner 
Schadek wrote:
> On Tuesday, 3 February 2015 at 10:33:25 UTC, Vadim Lopatin 
> wrote:
>>
>> ORM operations are not a simple single query/statement.
>> They often use several queries to load dependent objects.
>
> make it an output range
>
>>
>> Of course, some CTFE/UDAs may be used for generation of field 
>> list, but it is not very helpful IMO.
>
> IMO writing:
>
> foreach(it; db.select<User>("...")) {
> }
>
> is epic. you have entered std.(range|algorithm) land.

Implemented in v0.2.17 for select.

test:

     auto ds = new ConnectionPoolDataSourceImpl(new 
SQLITEDriver(), "ddbctest.sqlite");
     auto conn = ds.getConnection();
     scope(exit) conn.close();
     Statement stmt = conn.createStatement();
     scope(exit) stmt.close();
     // test data preparation
     stmt.executeUpdate("DROP TABLE IF EXISTS user");
     stmt.executeUpdate("CREATE TABLE user (id INTEGER PRIMARY 
KEY, name VARCHAR(255) NOT NULL, flags int null)");
     stmt.executeUpdate(`INSERT INTO user (id, name, flags) VALUES 
(1, "John", 5), (2, "Andrei", 2), (3, "Walter", 2), (4, "Rikki", 
3), (5, "Iain", 0), (6, "Robert", 1)`);

     // our POD struct
     struct User {
         long id;
         string name;
         int flags;
     }

     // let's execute select and nump query result
     foreach(user; stmt.select!User.where("id < 6").orderBy("name 
desc")) {
         writeln("id:", user.id, " name:", user.name, " flags:", 
user.flags);
     }

Output is:
------------------
id:3 name:Walter flags:2
id:4 name:Rikki flags:3
id:1 name:John flags:5
id:5 name:Iain flags:0
id:2 name:Andrei flags:2
------------------
Where and orderBy are optional - without them always reads all 
rows in default order.

Possible improvements: ability to specify field list to read only 
necessary fields.