On Tuesday, 3 February 2015 at 15:20:41 UTC, Vadim Lopatin wrote:
On Tuesday, 3 February 2015 at 14:41:02 UTC, Vadim Lopatin
wrote:
On Tuesday, 3 February 2015 at 10:49:07 UTC, Robert burner
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.
Update in v0.2.19: you can specify field list for select
writeln("reading all user table rows, but fetching only id
and name (you will see default value 0 in flags field)");
foreach(ref e; stmt.select!(User, "id", "name")) {
writeln("id:", e.id, " name:", e.name, " flags:",
e.flags);
}
output:
reading all user table rows, but fetching only id and name (you
will see default value 0 in flags field)
id:1 name:John flags:0
id:2 name:Andrei flags:0
id:3 name:Walter flags:0
id:4 name:Rikki flags:0
id:5 name:Iain flags:0
id:6 name:Robert flags:0
Small addition for D-style selects:
// now it's possible to use vars as destination
long id;
string name;
foreach(e; stmt.select!()("SELECT id, name FROM user", id,
name)) {
writeln("id:", id, " name:", name);
}
Result:
id:1 name:John
id:2 name:Andrei
id:3 name:Walter
id:4 name:Rikki
id:5 name:Iain
id:6 name:Robert
