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-rw-r--r--composite/driver.cxx10
-rw-r--r--hello/driver.cxx21
-rw-r--r--inverse/driver.cxx8
-rw-r--r--prepared/driver.cxx9
-rw-r--r--query/driver.cxx50
-rw-r--r--relationship/driver.cxx7
-rw-r--r--view/driver.cxx12
7 files changed, 74 insertions, 43 deletions
diff --git a/composite/driver.cxx b/composite/driver.cxx
index aaedf17..fc228bf 100644
--- a/composite/driver.cxx
+++ b/composite/driver.cxx
@@ -84,16 +84,16 @@ main (int argc, char* argv[])
//
{
typedef odb::query<person> query;
- typedef odb::result<person> result;
transaction t (db->begin ());
- result r (db->query<person> (
- query::name.extras.nickname == "Squeaky"));
+ auto_ptr<person> p (
+ db->query_one<person> (
+ query::name.extras.nickname == "Squeaky"));
- if (!r.empty ())
+ if (p.get () != 0)
{
- name& n (r.begin ()->name ());
+ name& n (p->name ());
cout << n.title () << " " << n.first () << " " << n.last () << endl;
}
diff --git a/hello/driver.cxx b/hello/driver.cxx
index a049c79..3a4de8c 100644
--- a/hello/driver.cxx
+++ b/hello/driver.cxx
@@ -78,14 +78,16 @@ main (int argc, char* argv[])
{
transaction t (db->begin ());
- result r (db->query<person> (query::first == "Joe" &&
- query::last == "Dirt"));
-
- result::iterator i (r.begin ());
+ // Here we know that there can be only one Joe Dirt in our
+ // database so we use the query_one() shortcut instead of
+ // manually iterating over the result returned by query().
+ //
+ auto_ptr<person> joe (
+ db->query_one<person> (query::first == "Joe" &&
+ query::last == "Dirt"));
- if (i != r.end ())
+ if (joe.get () != 0)
{
- auto_ptr<person> joe (i.load ());
joe->age (joe->age () + 1);
db->update (*joe);
}
@@ -99,11 +101,10 @@ main (int argc, char* argv[])
{
transaction t (db->begin ());
- odb::result<person_stat> r (db->query<person_stat> ());
-
- // The result of this query always has exactly one element.
+ // The result of this (aggregate) query always has exactly one element
+ // so use the query_value() shortcut.
//
- const person_stat& ps (*r.begin ());
+ person_stat ps (db->query_value<person_stat> ());
cout << endl
<< "count : " << ps.count << endl
diff --git a/inverse/driver.cxx b/inverse/driver.cxx
index d521579..5a613e1 100644
--- a/inverse/driver.cxx
+++ b/inverse/driver.cxx
@@ -202,7 +202,6 @@ main (int argc, char* argv[])
//
{
typedef odb::query<employee> query;
- typedef odb::result<employee> result;
session s;
transaction t (db->begin ());
@@ -216,10 +215,9 @@ main (int argc, char* argv[])
//
shared_ptr<position> se (new position ("Software Engineer"));
- result r (db->query<employee> (query::first == "John" &&
- query::last == "Doe"));
-
- shared_ptr<employee> john (r.begin ().load ());
+ shared_ptr<employee> john (
+ db->query_one<employee> (query::first == "John" &&
+ query::last == "Doe"));
john->employer (csi);
john->position (se);
diff --git a/prepared/driver.cxx b/prepared/driver.cxx
index 7d561a9..d805ddb 100644
--- a/prepared/driver.cxx
+++ b/prepared/driver.cxx
@@ -206,7 +206,6 @@ main (int argc, char* argv[])
{
typedef odb::query<person_count> query;
typedef odb::prepared_query<person_count> prep_query;
- typedef odb::result<person_count> result;
transaction t (db->begin ());
@@ -215,11 +214,11 @@ main (int argc, char* argv[])
prep_query pq (
db->prepare_query<person_count> ("person-count-age-query", q));
+ // Because an aggregate query result always contains one element,
+ // we use execute_value() insetad of execute() as a shortcut:
+ //
for (age = 90; age > 40; age -= 10)
- {
- result r (pq.execute ());
- cout << "over " << age << ": " << r.begin ()->count << endl;
- }
+ cout << "over " << age << ": " << pq.execute_value ().count << endl;
t.commit ();
}
diff --git a/query/driver.cxx b/query/driver.cxx
index fbd148d..aec8ac8 100644
--- a/query/driver.cxx
+++ b/query/driver.cxx
@@ -22,17 +22,21 @@ typedef odb::query<person> query;
typedef odb::result<person> result;
static void
-print (result& r)
+print (person& p)
{
- for (result::iterator i (r.begin ()); i != r.end (); ++i)
- {
- cout << i->first () << " ";
+ cout << p.first () << " ";
- if (!i->middle ().null ())
- cout << i->middle ().get () << " ";
+ if (!p.middle ().null ())
+ cout << p.middle ().get () << " ";
- cout << i->last () << " " << i->age () << endl;
- }
+ cout << p.last () << " " << p.age () << endl;
+}
+
+static void
+print (result& r)
+{
+ for (result::iterator i (r.begin ()); i != r.end (); ++i)
+ print (*i);
cout << endl;
}
@@ -90,7 +94,6 @@ main (int argc, char* argv[])
//
/*
person p ("", "", 0);
-
for (result::iterator i (r.begin ()); i != r.end (); ++i)
{
i.load (p);
@@ -103,6 +106,35 @@ main (int argc, char* argv[])
t.commit ();
}
+ // Use query_one() as a shortcut when there's no more than one element
+ // in the result.
+ //
+ {
+ transaction t (db->begin ());
+
+ auto_ptr<person> p (db->query_one<person> (query::age == 21));
+
+ if (p.get () != 0)
+ {
+ print (*p);
+ cout << endl;
+ }
+
+ // Or we can load the state into an existing object.
+ //
+ /*
+ person p ("", "", 0);
+
+ if (db->query_one<person> (query::age == 21, p))
+ {
+ print (p);
+ cout << endl;
+ }
+ */
+
+ t.commit ();
+ }
+
// Query that shows how to combine expressions with &&, ||, and !
// as well as use paranthesis to control evaluation order.
//
diff --git a/relationship/driver.cxx b/relationship/driver.cxx
index 9af06a2..27a31b2 100644
--- a/relationship/driver.cxx
+++ b/relationship/driver.cxx
@@ -132,10 +132,9 @@ main (int argc, char* argv[])
shared_ptr<employer> csi (db->load<employer> ("Complex Systems Inc"));
shared_ptr<project> ch (db->load<project> ("Complex Hardware"));
- result r (db->query<employee> (query::first == "John" &&
- query::last == "Doe"));
-
- shared_ptr<employee> john (r.begin ().load ());
+ shared_ptr<employee> john (
+ db->query_one<employee> (query::first == "John" &&
+ query::last == "Doe"));
john->employer (csi);
john->projects ().clear ();
diff --git a/view/driver.cxx b/view/driver.cxx
index 36274d6..cbe26ee 100644
--- a/view/driver.cxx
+++ b/view/driver.cxx
@@ -179,12 +179,14 @@ main (int argc, char* argv[])
{
transaction t (db->begin ());
- result<employee_count> r (
- db->query<employee_count> (query<employee_count>::last == "Doe"));
-
- // Result of this aggregate query contains only one element.
+ // Result of an aggregate query contains only one element so let's
+ // use the query_value() shortcut.
//
- cout << r.begin ()->count << " employees with the Doe last name" << endl
+ employee_count ec (
+ db->query_value<employee_count> (
+ query<employee_count>::last == "Doe"));
+
+ cout << ec.count << " employees with the Doe last name" << endl
<< endl;
t.commit ();
generated by cgit v1.1 at 2024-11-21 20:17:52 +0000