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// 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;
}
}
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