aboutsummaryrefslogtreecommitdiff
path: root/prepared/driver.cxx
diff options
context:
space:
mode:
authorBoris Kolpackov <boris@codesynthesis.com>2012-10-17 09:31:54 +0200
committerBoris Kolpackov <boris@codesynthesis.com>2012-10-17 09:31:54 +0200
commit8338bb049db44d9b470b2a76acc5853b92915238 (patch)
tree19f95ec98adadec6e4a8254a720c0b059d2bd927 /prepared/driver.cxx
parent1eb99114e1d7741ecdb5a6b2396c9cfd86c5dee4 (diff)
Add example for prepared query usage
Diffstat (limited to 'prepared/driver.cxx')
-rw-r--r--prepared/driver.cxx232
1 files changed, 232 insertions, 0 deletions
diff --git a/prepared/driver.cxx b/prepared/driver.cxx
new file mode 100644
index 0000000..470d0b8
--- /dev/null
+++ b/prepared/driver.cxx
@@ -0,0 +1,232 @@
+// file : prepared/driver.cxx
+// copyright : not copyrighted - public domain
+
+#include <memory> // std::auto_ptr
+#include <cassert>
+#include <iostream>
+
+#include <odb/database.hxx>
+#include <odb/connection.hxx>
+#include <odb/transaction.hxx>
+
+#include "database.hxx" // create_database
+
+#include "person.hxx"
+#include "person-odb.hxx"
+
+using namespace std;
+using namespace odb::core;
+
+struct params
+{
+ unsigned short age;
+ string first;
+};
+
+static void
+query_factory (const char* name, connection& c)
+{
+ typedef odb::query<person> query;
+
+ auto_ptr<params> p (new params);
+ query q (query::age > query::_ref (p->age) &&
+ query::first == query::_ref (p->first));
+ prepared_query<person> pq (c.prepare_query<person> (name, q));
+ c.cache_query (pq, p);
+}
+
+static void
+print_ages (unsigned short age, odb::result<person> r)
+{
+ cout << "over " << age << ':';
+
+ for (odb::result<person>::iterator i (r.begin ()); i != r.end (); ++i)
+ cout << ' ' << i->age ();
+
+ cout << endl;
+}
+
+int
+main (int argc, char* argv[])
+{
+ try
+ {
+ auto_ptr<database> db (create_database (argc, argv));
+
+ // Create a few persistent person objects.
+ //
+ {
+ person p1 ("John", "First", 91);
+ person p2 ("John", "Second", 81);
+ person p3 ("John", "Third", 71);
+ person p4 ("John", "Fourth", 61);
+ person p5 ("John", "Fifth", 51);
+
+ transaction t (db->begin ());
+ db->persist (p1);
+ db->persist (p2);
+ db->persist (p3);
+ db->persist (p4);
+ db->persist (p5);
+ t.commit ();
+ }
+
+ typedef odb::query<person> query;
+ typedef odb::prepared_query<person> prep_query;
+ typedef odb::result<person> result;
+
+ // Example of an uncached prepared query in the same transaction.
+ //
+ {
+ transaction t (db->begin ());
+
+ unsigned short age;
+ query q (query::age > query::_ref (age));
+ prep_query pq (db->prepare_query<person> ("person-age-query", q));
+
+ for (age = 90; age > 40; age -= 10)
+ {
+ result r (pq.execute ());
+ print_ages (age, r);
+ }
+
+ t.commit ();
+ }
+
+ // Example of an uncached prepared query in multiple transactions.
+ //
+ // Note that here we have to first obtain a connection, then prepare
+ // the query using this connection, and finally start each transaction
+ // that uses the prepared query on this connection.
+ //
+ {
+ connection_ptr conn (db->connection ());
+
+ unsigned short age;
+ query q (query::age > query::_ref (age));
+ prep_query pq (conn->prepare_query<person> ("person-age-query", q));
+
+ for (age = 90; age > 40; age -= 10)
+ {
+ transaction t (conn->begin ());
+
+ result r (pq.execute ());
+ print_ages (age, r);
+
+ t.commit ();
+ }
+ }
+
+ // Example of a cached prepared query without by-reference parameters.
+ //
+ for (unsigned short i (0); i < 5; ++i)
+ {
+ transaction t (db->begin ());
+
+ prep_query pq (db->lookup_query<person> ("person-val-age-query"));
+
+ if (!pq)
+ {
+ pq = db->prepare_query<person> (
+ "person-val-age-query", query::age > 50);
+ db->cache_query (pq);
+ }
+
+ result r (pq.execute ());
+ print_ages (50, r);
+
+ t.commit ();
+ }
+
+ // Example of a cached prepared query with by-reference parameters.
+ //
+ for (unsigned short age (90); age > 40; age -= 10)
+ {
+ transaction t (db->begin ());
+
+ unsigned short* age_param;
+ prep_query pq (
+ db->lookup_query<person> ("person-ref-age-query", age_param));
+
+ if (!pq)
+ {
+ auto_ptr<unsigned short> p (new unsigned short);
+ age_param = p.get ();
+ query q (query::age > query::_ref (*age_param));
+ pq = db->prepare_query<person> ("person-ref-age-query", q);
+ db->cache_query (pq, p); // Assumes ownership of p.
+ }
+
+ *age_param = age; // Initialize the parameter.
+ result r (pq.execute ());
+ print_ages (age, r);
+
+ t.commit ();
+ }
+
+ // Example of a cached prepared query that uses a query factory.
+ //
+ db->query_factory ("person-age-name-query", &query_factory);
+
+ for (unsigned short age (90); age > 40; age -= 10)
+ {
+ transaction t (db->begin ());
+
+ params* p;
+ prep_query pq (db->lookup_query<person> ("person-age-name-query", p));
+ assert (pq);
+
+ p->age = age;
+ p->first = "John";
+ result r (pq.execute ());
+ print_ages (age, r);
+
+ t.commit ();
+ }
+
+ // In C++11 the above call to query_factory() can be re-written to
+ // use a lambda function, for example:
+ //
+ /*
+ db->query_factory (
+ "person-age-name-query",
+ [] (const char* name, connection& c)
+ {
+ auto_ptr<params> p (new params);
+ query q (query::age > query::_ref (p->age) &&
+ query::first == query::_ref (p->first));
+ prepared_query<person> pq (c.prepare_query<person> (name, q));
+ c.cache_query (pq, p);
+ });
+ */
+
+ // Prepared queries can also be used with views, as shown in the
+ // following example.
+ //
+ {
+ typedef odb::query<person_count> query;
+ typedef odb::prepared_query<person_count> prep_query;
+ typedef odb::result<person_count> result;
+
+ transaction t (db->begin ());
+
+ unsigned short age;
+ query q (query::age > query::_ref (age));
+ prep_query pq (
+ db->prepare_query<person_count> ("person-count-age-query", q));
+
+ for (age = 90; age > 40; age -= 10)
+ {
+ result r (pq.execute ());
+ cout << "over " << age << ": " << r.begin ()->count << endl;
+ }
+
+ t.commit ();
+ }
+ }
+ catch (const odb::exception& e)
+ {
+ cerr << e.what () << endl;
+ return 1;
+ }
+}