Sqlite questions
lazarus / 43-Android

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CC · 2012-12-12 19:46

Felipe,

I have seen you have been working on the sqlite part lately.

I am planning to use  the virtual tables functionality  of Sqlite
quite heavily . The implementations of the tables are in pascal.  Here
are the questions:

How to create the modules for android?

For the GUI part it is still a question for me wether native code or
the FPC java compiler is the faster way to get the project finished. (
I could use some advice in this regard too. )

In the later case earlier versions of Android could be targeted, but
even then the VT modules would be better in native code if it is
possible. Is v2.2 the lowest possible target version even when there
is no GUI involved?

In the first case maybe the best solution would be to compile sqlite
into the app for speed and to avoid support problems. Is this a good
idea?

I know you are still at the beginning of the road to support sqlite
and some of these may be a little more advanced question. 

Cheers, CC

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Phil · 2012-12-12 19:52

If you code with FPC JVM, then you already have this access to the
Android Sqlite Java package:

http://developer.android.com/reference/android/database/sqlite/SQLiteD
atabase.html

See androidr.pas for the Pascal declarations for these methods.

Also, an intro to FPC JVM development:

http://web.fastermac.net/~MacPgmr/pba/PbaStatus.html

Since mobile devices running iOS and Android already include the
Sqlite library, my instinct would be the program against the API,
rather than linking the library into your executable.

Thanks.

-Phil

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felipemdc · 2012-12-13 09:36

Quote from: Phil on December 12, 2012, 08:52:58 pmIf you code with FPC
JVM, then you already have this access to the Android Sqlite Java
package:

http://developer.android.com/reference/android/database/sqlite/SQLiteD
atabase.html
And in native code you can access this class too, via JNI. Or how do
you think that I wrote the sqlite support?

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felipemdc · 2012-12-13 09:44

Quote from: CC on December 12, 2012, 08:46:18 pmI am planning to use 
the virtual tables functionality  of Sqlite quite heavily . The
implementations of the tables are in pascal.  Here are the questions:

How to create the modules for android?
I don't know anything about sqlite virtual tables functionality, but
in general, in Android you cannot access the sqlite native interface
at the moment. The sqlite shared object exists, but it is not part of
the NDK, so it is not allowed to use it. The only thing that we can
use is the Java class that Phil mentioned, which in native code can be
accessed via JNI:

http://developer.android.com/reference/android/database/sqlite/SQLiteD
atabase.html

So it might be that VT modules are not supported by the libraries
present in Android.

One solution would be to ship your own sqlite.so library inside your
project, and then you can access the native interface to it and use
VT.

QuoteIs v2.2 the lowest possible target version even when there is no
GUI involved?
Hard to tell, since I haven't written any no GUI Android project using
the LCL ... I am sure that for the LCL drawing 2.2 is absolutely
required.

But if you are not using graphics, what for are you using the LCL? You
can write a native JNI app without the LCL, using either the
traditional method used by the LCL or the NativeApplication support in
Android 2.3+

QuoteIn the first case maybe the best solution would be to compile
sqlite into the app for speed and to avoid support problems. Is this a
good idea?
Yes, it is probably the only way to have VT tables working in your
app.

You will need to either compile your own sqlite.so or find a pre-
compiled one. I already searched and a pre-compiled one a long time
ago, but can't remember where it is now ... have to recheck this.