SQLITE Database in Project



  • Hello everybody,

    i am trying to load data from an sqlite database.
    with the simulator it is possible to open the db when i use the following, but then the db is stored on "C:" and not in my projects folder. so i think that it would not work on device without copying the db manually.
    @db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("/db.sqlite");@

    because of that i tried to add it to my ressources like a picture:
    @db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName(":/database/db.sqlite");@
    (of course added in the .qrc file)

    but with this code its not working on device as well as with the simulator, because "open" fails.
    I think the App can't find the db, but why?

    Thanks you in advance!



  • SQLite databases cannot be stored in the Qt resource system. You must put it into regular files and distribute them along your application.

    The reason is simple: The database name is just the path to the file. Qt does not intercept the file name but hands it over directly to the SQLite functions (by calling toUtf8() on the “path”), which in turn try to open that file – and will eventually fail, of course.



  • Would it be possible with another kind of database? for example mysql or mssql? or is it generally not possible to store db's in qt resources?



  • No, it would not be possible with other database too. Even if you're using some embedded database (mysql comes into mind), these would suffer from the same problem, that Qt does not intercept the path.



  • so there's no way to use databases with qt on mobile device?
    And i have to use for example .csv ?



  • Provide the database file in your application bundle. I'm pretty sure you can have those in every mobile environment. Also, keep in mind that a file in a resource is read-only, you would never be able to write to that database.



  • ok, thanks for info!
    but now i have a problem!
    how can i use the information in the file/db in my app?
    i'd like to read and write to that file/db and want to bring the file/db with the app, so that i don't need to copy it on device manually.
    or is there another way to add it to my project? without the .qrc?



  • As far as I know it's possible to add this to some settings in the qmake project files, at least for symbian. But I have no experience on this. Please use the forum search and/or Google - I'm sure this was asked before.



  • Here's the solution for everybody who's interested in:

    use:
    @db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("db.sqlite");@

    and add this to your .pro file:
    @symbian {
    ...
    addFiles.sources = db.sqlite
    addFiles.path = .
    DEPLOYMENT += addFiles
    ...
    }
    @

    Thanks to Volker!



  • Hi All,
    I have tried in the same way.But i didnt get it.
    Basically i am developing the meego application in windows dev enviornment using Qt creator.

    Following are my pro file contents,

    @
    QT += core gui sql
    TARGET = AppName
    TEMPLATE = app
    target.path=/usr/local/bin
    INSTALLS=target
    SOURCES += ---
    ---
    HEADERS += ---
    ---
    FORMS += ---
    ---
    RESOURCES +=
    assests.qrc
    addFiles.sources =test.sqlite
    addFiles.path = .
    DEPLOYMENT += addFiles
    @

    So when i tried to build the file, automatically the other folde is added into my project directory and showing test.sqlite inside it;

    But when i tried with the following code

    @
    db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName(dbname);
    if(db.open())
    {
    // ITs always true;in the sense it automatically creates a new database name test.sqlite in the /usr/local/bin folder
    }
    @

    Please give some suggestions over this issue.

    Thanks,
    Vsh.Vshnu

    [EDIT: code formatting, please use @-tags, not stars (*), Volker]



  • Hi Vsh.Vshnu,

    Follow the SQLite examples given in Forum Nokia:
    "Creating an SQLite database in Qt":http://wiki.forum.nokia.com/index.php/CS001504_-Creating_an_SQLite_database_in_Qt
    "Searching for data in a database in Qt":http://wiki.forum.nokia.com/index.php/CS001507
    -_Searching_for_data_in_a_database_in_Qt

    Best regards,
    Leon



  • [quote author="leon.anavi" date="1305634618"]Hi Vsh.Vshnu,

    Follow the SQLite examples given in Forum Nokia:
    "Creating an SQLite database in Qt":http://wiki.forum.nokia.com/index.php/CS001504_-Creating_an_SQLite_database_in_Qt
    "Searching for data in a database in Qt":http://wiki.forum.nokia.com/index.php/CS001507
    -_Searching_for_data_in_a_database_in_Qt

    Best regards,
    Leon[/quote]

    Hi leon.anavi,
    My problem is different.Its becasuse i am not able to open a existing sqlite database inside project main folder.
    I want the sqlite files to be inside my application package file??



  • Then, what is the path stored in variable dbname?



  • Hi Volker,
    Its simply
    QString dbName="test.sqlite";

    Iam developing for meego in windows developement enviorment using Qt creator



  • the target path of your app is /usr/local/bin, the path of your db is test.sqlite - so the complete path is /usr/local/bin/test.sqlite. Sounds quite ok for me (in regard to the setup, a database file in /usr/local/bin is a no-go!).

    Do you have a test.sqlite that actually is packed in your setup?

    And be aware, the packing options are Symbian only!. It is ignored for any other operating systems, including Meego! It is for reason, that Matze5590 has put them into the symbian scope!



  • [quote author="vsh.vshnu" date="1305635099"]Hi Volker,
    Its simply
    QString dbName="test.sqlite";

    Iam developing for meego in windows developement enviorment using Qt creator[/quote]

    Try to use the absolute path. You can get the file path of the application executable using "QCoreApplication::applicationFilePath":http://doc.qt.nokia.com/latest/qcoreapplication.html#applicationFilePath

    Cheers,
    Leon



  • [quote author="leon.anavi" date="1305635864"]
    [quote author="vsh.vshnu" date="1305635099"]Hi Volker,
    Its simply
    QString dbName="test.sqlite";

    Iam developing for meego in windows developement enviorment using Qt creator[/quote]

    Try to use the absolute path. You can get the file path of the application executable using "QCoreApplication::applicationFilePath":http://doc.qt.nokia.com/latest/qcoreapplication.html#applicationFilePath
    Cheers,
    Leon

    [/quote]

    Hi Leon,
    Thanks for the support ,
    I have tried using the QCoreApplication::applicationFilePath
    @QString dbName=QCoreApplication::applicationFilePath()+“\test.sqlite”;@
    But it seems not opening the database.
    All I wanted to pack the sqlite database inside my application so that i can install the applications as a single unit.



  • [quote author="Volker" date="1305635745"]Do you have a test.sqlite that actually is packed in your setup?
    [/quote]

    [quote author="vsh.vshnu" date="1305636668"]
    All I wanted to pack the sqlite database inside my application so that i can install the applications as a single unit.
    [/quote]

    I think you should follow Volker's hint :) Please read "MeeGo Packaging/Guidelines":http://wiki.meego.com/Packaging/Guidelines As you probably know MeeGo apps are distributed as rpm so you have to include your database into the rpm.



  • [quote author="leon.anavi" date="1305637109"][quote author="Volker" date="1305635745"]Do you have a test.sqlite that actually is packed in your setup?
    [/quote]

    [quote author="vsh.vshnu" date="1305636668"]
    All I wanted to pack the sqlite database inside my application so that i can install the applications as a single unit.
    [/quote]

    I think you should follow Volker's hint :) Please read "MeeGo Packaging/Guidelines":http://wiki.meego.com/Packaging/Guidelines As you probably know MeeGo apps are distributed as rpm so you have to include your database into the rpm.

    [/quote]

    Thanks for the help.. i will look into it..

    Thanks & Regards,
    Vsh.Vshnu



  • @goetz
    some time , we need store a read-only database file in the QRC file. just need read no need change.
    store in qrc file will avoid use change ,delete....etc it. and use database file (qsqlite3 ) will be fast get query result.

    now qt version is 5.8. can we do it ?

    best regards,


  • Qt Champions 2016

    @cawlfj

    Hi
    If small database, you can just copy
    it to file system upon run and
    open it.

    Just override it each time.

    I do not think its possible to have a db in qrc.



  • @mrjj yes , you are right . we can do as your way. but i think if the db file in inside the qrc file will be more safety than copy out.
    Some time , some data , we don't want some body to get it .


  • Qt Champions 2016

    @cawlfj
    Well its not impossible to still dig it out using a hex editor.
    For dbs, something like
    https://www.zetetic.net/sqlcipher/about/
    might be better.
    Maybe you can use the dump trick to upload to a :mem based db.
    http://stackoverflow.com/questions/3826552/in-python-how-can-i-load-a-sqlite-db-completely-to-memory-before-connecting-to
    Disclaimer: i never tried this.


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