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examples/ForumNokia/DBMS/src/DBMSEngine.cpp

00001 /*
00002  * Copyright  2008 Nokia Corporation.
00003  */
00004 
00005 #include     // CDesCArrayFlat
00006 #include     // CFileStore & CPermanentFileStore
00007 #include     // file helpers
00008 #include 
00009 #include "DBMSEngine.h"
00010 
00011 // Implementation specific constants
00012 const int KCustomSqlMaxLength = 256;
00013 const int KArrayGranularity = 5;     // for CDesCArrayFlat
00014 
00015 // ---------------------------------------------------------------------------
00016 // CBookDb::NewL()
00017 //
00018 // Create instance of the Book database engine.
00019 // ---------------------------------------------------------------------------
00020 CBookDb* CBookDb::NewL() 
00021     {
00022     CBookDb* tmp = new (ELeave)CBookDb();
00023     CleanupStack::PushL(tmp);
00024     tmp->ConstructL();
00025     CleanupStack::Pop();
00026     return tmp;
00027     }
00028 
00029 // ---------------------------------------------------------------------------
00030 // CBookDb::~CBookDb()
00031 //
00032 // Destructor of the Book database engine. Release resources.
00033 // ---------------------------------------------------------------------------
00034 CBookDb::~CBookDb()
00035     {
00036     Close();  // Just in case, if the user does not close this explicitely
00037     iFsSession.Close();
00038     }
00039 
00040 // ---------------------------------------------------------------------------
00041 // CBookDb::ConstructL()
00042 //
00043 // Second phase construction. Leaves, if RFs session cannot be created.
00044 // ---------------------------------------------------------------------------
00045 void CBookDb::ConstructL()
00046     {
00047     TInt err = iFsSession.Connect();
00048     if(err)
00049         User::Leave(err);
00050     }
00051 
00052 // ---------------------------------------------------------------------------
00053 // CBookDb::CBookDb()
00054 //
00055 // Constructor
00056 // ---------------------------------------------------------------------------
00057 CBookDb::CBookDb()
00058     {
00059     iOpen = EFalse;
00060     }
00061 
00062 // ---------------------------------------------------------------------------
00063 // CBookDb::OpenDbL()
00064 //
00065 // Open existing Book database for exclusive access.
00066 // ---------------------------------------------------------------------------
00067 TInt CBookDb::OpenDb(const TFileName& aExistingBookFile)
00068     {
00069     Close();
00070 
00071     if(!BaflUtils::FileExists(iFsSession, aExistingBookFile))
00072         {
00073             return KErrNotFound;
00074         }
00075 
00076         TRAPD(error, 
00077                 iFileStore = CPermanentFileStore::OpenL(iFsSession, aExistingBookFile, 
00078                         EFileRead|EFileWrite);
00079                 iFileStore->SetTypeL(iFileStore->Layout());/* Set file store type*/
00080                 iBookDb.OpenL(iFileStore,iFileStore->Root())
00081                 );
00082     if(error!=KErrNone)
00083     {
00084         return error;
00085     }
00086     
00087     iOpen = ETrue;
00088     return KErrNone;
00089     }
00090 
00091 // ---------------------------------------------------------------------------
00092 // CBookDb::CreateDbL()
00093 //
00094 // Create a new database. The database will be in exclusive access mode.
00095 // ---------------------------------------------------------------------------
00096 TInt CBookDb::CreateDb(const TFileName& aNewBookFile)
00097     {
00098     Close();
00099 
00100     // Create empty database file.
00101     TRAPD(error,
00102         iFileStore = CPermanentFileStore::ReplaceL(iFsSession, aNewBookFile, 
00103                 EFileRead|EFileWrite);
00104         iFileStore->SetTypeL(iFileStore->Layout());// Set file store type
00105         TStreamId id = iBookDb.CreateL(iFileStore);// Create stream object
00106         iFileStore->SetRootL(id);// Keep database id as root of store
00107         iFileStore->CommitL();// Complete creation by commiting
00108         // Create Book tables and indexes
00109         CreateBooksTableL();
00110         CreateBooksIndexL();
00111         );
00112     
00113     if(error!=KErrNone)
00114     {
00115         return error;
00116     }
00117     iOpen = ETrue;
00118     return KErrNone;
00119     }
00120 
00121 // ---------------------------------------------------------------------------
00122 // CBookDb::RemoveDb()
00123 //
00124 // First remove the Books table. Then remove the database file.
00125 // ---------------------------------------------------------------------------
00126 TInt CBookDb::RemoveDb(const TFileName& aExistingBookFile)
00127     {
00128     Close();
00129 
00130     if(!BaflUtils::FileExists(iFsSession, aExistingBookFile))
00131         {
00132             return KErrNotFound;
00133         }
00134 
00135     // It is enough to delete the database file directly. Because this example
00136     // demonstrates DDL statements, it first opens and drops the Books table.
00137 
00138         TInt error = OpenDb(aExistingBookFile);
00139         if(error!=KErrNone)
00140     {
00141         return error;
00142     }
00143     
00144     DropBooksTable();
00145     Close();
00146 
00147     iFsSession.Delete(aExistingBookFile);
00148     return KErrNone;
00149     }
00150 
00151 // ---------------------------------------------------------------------------
00152 // CBookDb::Close()
00153 //
00154 // Close the database.
00155 // ---------------------------------------------------------------------------
00156 TInt CBookDb::Close()
00157     {
00158     iBookDb.Close();
00159     if(iFileStore)
00160         {
00161         delete iFileStore;
00162         iFileStore = NULL;
00163         }
00164     iOpen = EFalse;
00165     return KErrNone;
00166     }
00167 
00168 // ---------------------------------------------------------------------------
00169 // CBookDb::IsOpen()
00170 //
00171 // Return open status of the database.
00172 // ---------------------------------------------------------------------------
00173 TBool CBookDb::IsOpen() const
00174     {
00175     return iOpen;
00176     }
00177 
00178 // ---------------------------------------------------------------------------
00179 // CBookDb::CreateBooksTableL()
00180 //
00181 // Creates Books table. Leaves, if the table cannot be created.
00182 // ---------------------------------------------------------------------------
00183 void CBookDb::CreateBooksTableL()
00184     {
00185 
00186     // Specify columns for Books table
00187     TDbCol authorCol(KBooksAuthorCol, EDbColText);   // Using default length
00188     TDbCol titleCol(KBooksTitleCol, EDbColText, KTitleMaxLength);
00189     titleCol.iAttributes = TDbCol::ENotNull;
00190     TDbCol descriptionCol(KBooksDescriptionCol, EDbColLongText); // Stream Data
00191 
00192     // Add the columns to column set
00193     CDbColSet* bookColSet = CDbColSet::NewLC();
00194     bookColSet->AddL(authorCol);
00195     bookColSet->AddL(titleCol);
00196     bookColSet->AddL(descriptionCol);
00197 
00198     // Create the Books table
00199     User::LeaveIfError(iBookDb.CreateTable(KBooksTable,
00200         *bookColSet));
00201     CleanupStack::PopAndDestroy(bookColSet);
00202     }
00203 
00204 // ---------------------------------------------------------------------------
00205 // CBookDb::CreateBooksIndexL()
00206 //
00207 // Creates an index for Books table. Leaves, if the index cannot be created.
00208 // ---------------------------------------------------------------------------
00209 void CBookDb::CreateBooksIndexL()
00210     {
00211     // Create index consisting of two columns
00212     TDbKeyCol authorCol(KBooksAuthorCol);
00213     TDbKeyCol titleCol(KBooksTitleCol);
00214 
00215     CDbKey* index = CDbKey::NewLC();   // create index key set
00216     index->AddL(titleCol);
00217     index->AddL(authorCol);
00218     User::LeaveIfError(iBookDb.CreateIndex(
00219         KBooksIndexName, KBooksTable, *index));
00220     CleanupStack::PopAndDestroy(index);
00221     }
00222 
00223 // ---------------------------------------------------------------------------
00224 // CBookDb::DropBooksTable()
00225 //
00226 // Drop the Books table incrementally. Uses RDbIncremental and DDL statement.
00227 // ---------------------------------------------------------------------------
00228 void CBookDb::DropBooksTable()
00229     {
00230     
00231     _LIT(KDropTable, "DROP TABLE ");
00232 
00233     // Sql: DROP TABLE Books
00234     TBuf sqlStr;
00235     sqlStr.Append(KDropTable);
00236     sqlStr.Append(KBooksTable);
00237 
00238     RDbIncremental incOp;
00239     TInt incStep = 0xFFFF;
00240     // Initialise Execution
00241     TInt incStat = incOp.Execute(iBookDb, sqlStr, incStep);
00242     while (incStep>0 && incStat==KErrNone)
00243         {
00244         incStat = incOp.Next(incStep); // Do the work
00245         }
00246     incOp.Close();
00247     }
00248 
00249 // ---------------------------------------------------------------------------
00250 // CBookDb::AddBookWithSqlL()
00251 //
00252 // Add a book to database using RDbView and SQL
00253 // ---------------------------------------------------------------------------
00254 TInt CBookDb::AddBookWithSql(const TDesC& aAuthor,
00255                          const TDesC& aTitle,
00256                          const TDesC& aDescription)
00257     {
00258 
00259     if(aAuthor.Length()==0 || aTitle.Length()==0 || aDescription.Length()==0)
00260         {
00261         return KErrGeneral;
00262         }
00263 
00264         _LIT(KSelect, "SELECT ");
00265         _LIT(KFrom, " FROM ");
00266         _LIT(KOrderBy, " ORDER BY ");
00267         _LIT(KDot, ", ");
00268 
00269     // Sql: SELECT Author, Title, Description FROM Books ORDER BY Title, Author
00270     TBuf sqlStr;
00271     
00272     sqlStr.Append(KSelect);
00273     sqlStr.Append(KBooksAuthorCol);
00274     sqlStr.Append(KDot);
00275     sqlStr.Append(KBooksTitleCol);
00276     sqlStr.Append(KDot);
00277     sqlStr.Append(KBooksDescriptionCol);
00278     sqlStr.Append(KFrom);
00279     sqlStr.Append(KBooksTable);
00280     sqlStr.Append(KOrderBy);
00281     sqlStr.Append(KBooksTitleCol);
00282     sqlStr.Append(KDot);
00283     sqlStr.Append(KBooksAuthorCol);
00284 
00285     RDbView view;    // Create a view on the database
00286     TInt error;
00287     error = view.Prepare(iBookDb, TDbQuery(sqlStr, EDbCompareFolded));
00288     if(error!=KErrNone)
00289     {
00290         return error;
00291     }
00292     error = view.EvaluateAll();
00293     if(error!=KErrNone)
00294     {
00295         return error;
00296     }
00297     RDbColWriteStream writeStream;  // Use stream to insert the description
00298     
00299     TRAP(error,
00300         view.InsertL();  // Insert a row. Column order matches sql select statement
00301         view.SetColL(1, aAuthor);
00302                 view.SetColL(2, aTitle);
00303         writeStream.OpenL(view, 3);
00304         writeStream.WriteL(aDescription);
00305         
00306         );
00307     if(error!=KErrNone)
00308     {
00309         return error;
00310     }
00311     writeStream.Close();
00312     TRAP(error, view.PutL()); // Complete insertion
00313         if(error!=KErrNone)
00314     {
00315         return error;
00316     } 
00317     view.Close();
00318     return KErrNone;
00319     }
00320 
00321 // ---------------------------------------------------------------------------
00322 // CBookDb::AddBookWithCppApiL()
00323 //
00324 // Add a book to database using RDbTable API
00325 // ---------------------------------------------------------------------------
00326 TInt CBookDb::AddBookWithCppApiL(const TDesC& aAuthor,
00327                             const TDesC& aTitle,
00328                             const TDesC& aDescription)
00329     {
00330 
00331     if(aAuthor.Length()==0 || aTitle.Length()==0 || aDescription.Length()==0)
00332         {
00333         return KErrGeneral;
00334         }
00335 
00336     // Create an updateable database table object
00337     RDbTable table;
00338     TInt err = table.Open(iBookDb, KBooksTable, table.EUpdatable);
00339     
00340     if(err!=KErrNone)
00341     {
00342         return err;
00343     }
00344     
00345         CDbColSet* booksColSet = table.ColSetL();
00346     CleanupStack::PushL(booksColSet);
00347     
00348     table.Reset();
00349     RDbColWriteStream writeStream;
00350     
00351     TRAPD(error,
00352         table.InsertL();
00353         table.SetColL(booksColSet->ColNo(KBooksAuthorCol), aAuthor); // col = 1
00354         table.SetColL(booksColSet->ColNo(KBooksTitleCol), aTitle);   // col = 2
00355         // Use a stream for the long text column
00356                 writeStream.OpenL(table, booksColSet->ColNo(KBooksDescriptionCol));
00357         writeStream.WriteL(aDescription);
00358         );
00359 
00360         if(error!=KErrNone)
00361     {
00362         return error;
00363     }   
00364         writeStream.Close();
00365         
00366     TRAP(err, table.PutL());    // Complete changes (the insertion)
00367         if(err!=KErrNone)
00368     {
00369         return err;
00370     }   
00371     
00372     CleanupStack::PopAndDestroy(booksColSet);
00373     table.Close();
00374         
00375     return KErrNone;
00376 
00377     }
00378 
00379 // ---------------------------------------------------------------------------
00380 // CBookDb::GetAllBooksL()
00381 //
00382 // Get array of all books in database. Format of each array item is:
00383 //      |