Line data Source code
1 : /***********************************************************************\
2 : * gnc-sql-object-backend.hpp: Encapsulate per-class table schema. *
3 : * *
4 : * Copyright 2016 John Ralls <jralls@ceridwen.us> *
5 : * *
6 : * This program is free software; you can redistribute it and/or *
7 : * modify it under the terms of the GNU General Public License as *
8 : * published by the Free Software Foundation; either version 2 of *
9 : * the License, or (at your option) any later version. *
10 : * *
11 : * This program is distributed in the hope that it will be useful, *
12 : * but WITHOUT ANY WARRANTY; without even the implied warranty of *
13 : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
14 : * GNU General Public License for more details. *
15 : * *
16 : * You should have received a copy of the GNU General Public License *
17 : * along with this program; if not, contact: *
18 : * *
19 : * Free Software Foundation Voice: +1-617-542-5942 *
20 : * 51 Franklin Street, Fifth Floor Fax: +1-617-542-2652 *
21 : * Boston, MA 02110-1301, USA gnu@gnu.org *
22 : \***********************************************************************/
23 :
24 : #ifndef __GNC_SQL_OBJECT_BACKEND_HPP__
25 : #define __GNC_SQL_OBJECT_BACKEND_HPP__
26 :
27 : #include <qof.h>
28 :
29 : #include <memory>
30 : #include <string>
31 : #include <vector>
32 :
33 : class GncSqlBackend;
34 : class GncSqlColumnTableEntry;
35 : using GncSqlColumnTableEntryPtr = std::shared_ptr<GncSqlColumnTableEntry>;
36 : using EntryVec = std::vector<GncSqlColumnTableEntryPtr>;
37 :
38 : #define GNC_SQL_BACKEND "gnc:sql:1"
39 :
40 : /**
41 : * Encapsulates per-class table schema with functions to load, create a table,
42 : * commit a changed front-end object (note that database transaction semantics
43 : * are not yet implemented; edit/commit applies to the front-end object!) and
44 : * write all front-end objects of the type to the database. Additional functions
45 : * for creating and running queries existed but were unused and untested. They've
46 : * been temporarily removed until the front end is ready to use them.
47 : */
48 : class GncSqlObjectBackend
49 : {
50 : public:
51 300 : GncSqlObjectBackend (int version, const std::string& type,
52 300 : const std::string& table, const EntryVec& vec) :
53 300 : m_table_name{table}, m_version{version}, m_type_name{type},
54 600 : m_col_table(vec) {}
55 300 : virtual ~GncSqlObjectBackend() = default;
56 : /**
57 : * Load all objects of m_type in the database into memory.
58 : * @param sql_be The GncSqlBackend containing the database connection.
59 : */
60 : virtual void load_all (GncSqlBackend* sql_be) = 0;
61 : /**
62 : * Conditionally create or update a database table from m_col_table. The
63 : * condition is the version returned by querying the database's version
64 : * table: If it's 0 then the table wasn't found and will be created; All
65 : * tables areat least version 1. If the database's version is less than the
66 : * compiled version then the table schema is upgraded but the data isn't,
67 : * that's the engine's responsibility when the object is loaded. If the
68 : * version is greater than the compiled version then nothing is touched.
69 : * @param sql_be The GncSqlBackend containing the database connection.
70 : */
71 : virtual void create_tables (GncSqlBackend* sql_be);
72 : /**
73 : * UPDATE/INSERT a single instance of m_type_name into the database.
74 : * @param sql_be The GncSqlBackend containing the database.
75 : * @param inst The QofInstance to be written out.
76 : */
77 : virtual bool commit (GncSqlBackend* sql_be, QofInstance* inst);
78 : /**
79 : * Write all objects of m_type_name to the database.
80 : * @param sql_be The GncSqlBackend containing the database.
81 : * @return true if the objects were successfully written, false otherwise.
82 : */
83 48 : virtual bool write (GncSqlBackend* sql_be) { return true; }
84 : /**
85 : * Return the m_type_name for the class. This value is created at
86 : * compilation time and is called QofIdType or QofIdTypeConst in other parts
87 : * of GnuCash. Most values are defined in src/engine/gnc-engine.h.
88 : * @return m_type_name.
89 : */
90 300 : const char* type () const noexcept { return m_type_name.c_str(); }
91 : /**
92 : * Compare a version with the compiled version (m_version).
93 : * @return true if they match.
94 : */
95 : const bool is_version (int version) const noexcept {
96 : return version == m_version;
97 : }
98 : /**
99 : * Check the presence of an object in the backend's database.
100 : *
101 : * @param sql_be Backend owning the database
102 : * @param inst QofInstance to be checked.
103 : */
104 : bool instance_in_db(const GncSqlBackend* sql_be,
105 : QofInstance* inst) const noexcept;
106 : protected:
107 : const std::string m_table_name;
108 : const int m_version;
109 : const std::string m_type_name; /// The front-end QofIdType
110 : const EntryVec& m_col_table; /// The ORM table definition.
111 : };
112 :
113 : using GncSqlObjectBackendPtr = std::shared_ptr<GncSqlObjectBackend>;
114 :
115 : using OBEEntry = std::tuple<std::string, GncSqlObjectBackendPtr>;
116 : using OBEVec = std::vector<OBEEntry>;
117 :
118 : /**
119 : * Data-passing struct for callbacks to qof_object_foreach() used in
120 : * GncSqlObjectBackend::write(). Once QofCollection is rewritten to use C++
121 : * containers we'll use std::foreach() and lambdas instead of callbacks and this
122 : * can go away.
123 : */
124 : struct write_objects_t
125 : {
126 1 : write_objects_t() = default;
127 66 : write_objects_t (GncSqlBackend* sql_be, bool o, GncSqlObjectBackend* e) :
128 66 : be{sql_be}, is_ok{o}, obe{e} {}
129 19 : void commit (QofInstance* inst) {
130 19 : if (is_ok) is_ok = obe->commit (be, inst);
131 19 : }
132 : GncSqlBackend* be = nullptr;
133 : bool is_ok = false;
134 : GncSqlObjectBackend* obe = nullptr;
135 : };
136 :
137 :
138 : #endif //__GNC_SQL_OBJECT_BACKEND_HPP__
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