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125 lines
4.7 KiB
125 lines
4.7 KiB
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KexiDB Module API Changes
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Doc started: 2003-07-08 by js@iidea.pl
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--------------------------------------------
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These changes are propsals for further disscussions.
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1. *** RENAMING ***
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Some classes can be betted described with other names:
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class KexiDBInterfaceManager -> KexiDBDriverManager
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Motivation: 'Interface' is a more generic term. Thus, the class name is not a description.
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'Driver Manager' term is also used in the iODBC package.
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2. Now, KexiDB is just another ODBC-like layer. Probably there woudn't be too much drivers
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for KexiDB if KexiDB will be still like it is.
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What to change?
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KexiDB should be merged with non-visual (but db-related) parts of KexiProject.
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KexiProject then should be renamed to KexiDBProject and be moved to KexiDB.
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Visual (document-like) project container (formerly KexiProject) that inherits KoDocument
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could be then named to something else and still exist since Kexi, as KOffice application,
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needs to implement KoDocument. (KexiProjectHandler is also visual-related)
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What we got then?
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After that move, KexiProject becames a non-visual general-purpose entity. SO it can be instantiated
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not only as Kexi Koffice document window, but also:
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- for batch (non-visual) data processing (equivalents of given features availabe from gui, e.g. data export)
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- for easy use in Kexi plugins and/or other apps that would know about enchanced database properties
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provided by Kexi projects' metadata
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- to enable linking current Kexi project with external Kexi projects' data, in the future (these external
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projects do not have to be visible as regular projects, but its metadata is loaded)
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Other motivation:
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It's not necessary for KexiProject to be dependent on KOfficelibs.
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3. KexiDBConnection should be moved to KexiDB module and it should be only connection data container.
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4. Kexi uses KoStore as medium for storing project's meta data.
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What if we want to store even this data in the database?
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We need more generic class KexiDBProjectStore for this of extend KoStore. Note that extending
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KoStore may not be possible (or nice) because of hierarchical (fs-like) structure of this medium,
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while db store is relational.
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Why to store Kexi projects in the db?
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- We can utilize transactional, multiuser features of databases "for free"
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- Using sqlite engine we can still store projects in local files.
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So, maybe drop KoStore completely? Oh, maybe not, but we can treat this format as xml-exported,
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mainly for external processing, migration and backups.
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Note that there can be one database location for storing project's user data and completely other location
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for the database that has stored project's meta-data (see example below).
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5. Example usage of db engine, to get both project metadata and raw db connection
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{
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kdDebug() << "DRIVERS:" << KexiDBEnginesManager::enginesNames() << endl;
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KexiDBEngine *engine = KexiDBEngineManager::engine("mysql");
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if (!engine) {
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kdDebug() << "no engine" << endl;
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return 1;
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}
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//we can also get the manager obj. with: KexiDBEnginesManager *manager = KexiDBEnginesManager::self();
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//connection data that can be later reused
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KexiDBConnectionData conn_data;
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conn_data.host = "myhost";
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conn_data.password = "mypwd";
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KexiDBConnection *conn = engine->createConnection(conn_data);
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if (!conn->connect()) {
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kdDebug() << "err. connect" << endl;
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return 1;
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}
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kdDebug() << "DATABASES:" << conn->dbNames() << endl;
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//we want use this connection to load given Kexi Project:
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KexiDBProject *prj = new KexiDBProject( conn, "test" );
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/* connection 'conn' has been opened for project meta-data source:
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KexiDBProjectStore *store = new KexiDBProjectStore( conn )
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Kexi then opens data base with KexiDBConnection::openDatabase( name )
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where 'name' comes from meta-data.
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This new connection is for projects' data.
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*/
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/* we could also load project from a file:
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KexiDBProject *prj = new KexiDBProject( "~/myprj.kexi" );
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Then, KexiProject will be loaded from the file:
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KexiDBProjectStore *store = new KexiDBProjectStore( "~/myprj.kexi" );
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..and data connection will be established as before.
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*/
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if (!prj)
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kdDebug() << "err. open db" << endl;
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return 1;
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}
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kdDebug() << "TABLE DEFS:" << prj->tableDefsNames() << endl;
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kdDebug() << "QUERY DEFS:" << prj->queryDefsNames() << endl;
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KexiDBTableDef *tab_def = prj->tableDef("people") << endl;
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if (!tab_def)
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kdDebug() << "no table def" << endl;
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return 1;
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}
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kdDebug() << "TABLE DEF FIELDS:" << tab_def->fieldsNames() << endl;
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KexiDBFieldDef *field = tab_def->field("age");
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if (!field)
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kdDebug() << "no such field" << endl;
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return 1;
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}
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kdDebug() << "FIELD TYPE:" << field->typeName() << endl;
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return 0;
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} |