1 // Boost.Geometry (aka GGL, Generic Geometry Library)
2 //
3 // Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
4 //
5 // Use, modification and distribution is subject to the Boost Software License,
6 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
7 // http://www.boost.org/LICENSE_1_0.txt)
8 // Boost.Geometry (aka GGL, Generic Geometry Library)
9 // SOCI example
10
11 // c: using WKB to retrieve geometries
12
13 // SOCI is a generic C++ template interface to access relational databases
14
15 // To build and run this example, see comments in example a
16 // Alternatively compile composing and executing compiler command directoy in examples directory,
17 // for example using GCC compiler:
18 // g++ -I../../../boost -I/home/mloskot/usr/include/soci \
19 // -I /home/mloskot/usr/include/soci/postgresql -I/usr/include/postgresql \
20 // -L/home/mloskot/usr/lib -lsoci_core-gcc-3_0 -lsoci_postgresql-gcc-3_0 x03_c_soci_example.cpp
21
22 #include <soci.h>
23 #include <soci-postgresql.h>
24
25 #include <exception>
26 #include <iostream>
27 #include <iterator>
28 #include <string>
29 #include <vector>
30
31 #include <boost/geometry/geometry.hpp>
32 #include <boost/geometry/geometries/geometries.hpp>
33 #include <boost/geometry/extensions/gis/io/wkb/read_wkb.hpp>
34 #include <boost/geometry/extensions/gis/io/wkb/utility.hpp>
35 #include <boost/geometry/io/wkt/wkt.hpp>
36
37 // user-defined type with GGL geometry
38 struct tree
39 {
40 int id;
41 boost::geometry::model::point<float, 2, boost::geometry::cs::geographic<boost::geometry::degree> > location;
42 };
43
44 // conversion of row of result to user-defined type - performs WKB parsing
45 namespace soci
46 {
47 template <>
48 struct type_conversion<tree>
49 {
50 typedef soci::values base_type;
51
from_basesoci::type_conversion52 static void from_base(base_type const& v, soci::indicator ind, tree& value)
53 {
54 try
55 {
56 value.id = v.get<int>("id");
57
58 // intermediate step: hex-encoded binary string to raw WKB
59 std::string const& hex = v.get<std::string>("wkb");
60 std::vector<unsigned char> wkb;
61 if (!boost::geometry::hex2wkb(hex, std::back_inserter(wkb)))
62 throw std::runtime_error("hex2wkb translation failed");
63
64 // parse WKB and construct point geometry
65 if (!boost::geometry::read_wkb(wkb.begin(), wkb.end(), value.location))
66 throw std::runtime_error("read_wkb failed");
67 }
68 catch(const std::exception& e)
69 {
70 std::cout << e.what() << std::endl;
71 }
72 }
73
to_basesoci::type_conversion74 static void to_base(tree const& value, base_type& v, soci::indicator& ind)
75 {
76 throw std::runtime_error("todo: wkb writer not yet implemented");
77 }
78 };
79 }
80
main()81 int main()
82 {
83 try
84 {
85 // establish database connection
86 soci::session sql(soci::postgresql, "dbname=ggl user=ggl password=ggl");
87
88 // construct schema of table for trees (point geometries)
89 sql << "DELETE FROM geometry_columns WHERE f_table_name = 'trees'";
90 sql << "DROP TABLE IF EXISTS trees CASCADE";
91 sql << "CREATE TABLE trees (id INTEGER)";
92 sql << "SELECT AddGeometryColumn('trees', 'geom', -1, 'POINT', 2)";
93
94 // insert sample data using plain WKT input
95 sql << "INSERT INTO trees VALUES(1, ST_GeomFromText('POINT(1.23 2.34)', -1))";
96 sql << "INSERT INTO trees VALUES(2, ST_GeomFromText('POINT(3.45 4.56)', -1))";
97 sql << "INSERT INTO trees VALUES(3, ST_GeomFromText('POINT(5.67 6.78)', -1))";
98 sql << "INSERT INTO trees VALUES(4, ST_GeomFromText('POINT(7.89 9.01)', -1))";
99
100 // query data in WKB form and read to geometry object
101 typedef std::vector<tree> trees_t;
102 soci::rowset<tree> rows = (sql.prepare << "SELECT id, encode(ST_AsBinary(geom), 'hex') AS wkb FROM trees");
103 trees_t trees;
104 std::copy(rows.begin(), rows.end(), std::back_inserter(trees));
105
106 // print trees output
107 for (trees_t::const_iterator it = trees.begin(); it != trees.end(); ++it)
108 {
109 std::cout << "Tree #" << it->id << " located at\t" << boost::geometry::wkt(it->location) << std::endl;
110 }
111 }
112 catch (std::exception const &e)
113 {
114 std::cerr << "Error: " << e.what() << '\n';
115 }
116 return 0;
117 }
118
119