Python Sample SQLite

It is possible to access SQLite files in Truxton without first exporting them to your local system.

APSW

Since the Python DB-API only supports establishing a connection to a SQLite database by providing a file name, we have to create our own filesystem to read from the file in Truxton. SQLite has the concept of virtual filesystems but DB-API doesn't support it. However, another SQLite library called APSW does. Install it using pip:

pip install apsw

You can verify that it is working by running the following script:

import sys
import apsw
import apsw.ext

def main() -> None:

  print("      Using APSW file", apsw.__file__)
  print("         APSW version", apsw.apsw_version())
  print("SQLite header version", apsw.SQLITE_VERSION_NUMBER)
  print("   SQLite lib version", apsw.sqlite_lib_version())
  print("   Using amalgamation", apsw.using_amalgamation)

  return None

if __name__ == "__main__":
  sys.exit(main())

SQLite in Truxton

Here's a script to query a SQLite database that is stored in Truxton.

import sys
import os
import apsw

from pathlib import Path

sys.path.append('C:/Program Files/Truxton/SDK')
import truxton

def main() -> None:

  truxton_virtual_filesystem = TruxtonVFS()
  truxton_virtual_filesystem.Truxton = truxton.create()
  
  database = apsw.Connection( "65d9d912-7328-d2e7-d511-f909000000c6", flags = SQLITE_OPEN_READONLY, vfs = "truxton")
  
  for row in database.execute("SELECT Z_UUID FROM Z_METADATA"):
    print(row)
  
  database.close()

  return None

SQLITE_OPEN_READONLY = 0x00000001

class TruxtonVFS(apsw.VFS):
  
  Truxton = None

  def __init__(self, vfsname="truxton", basevfs=""):
    self.vfs_name = vfsname
    self.base_vfs = basevfs
    super().__init__(self.vfs_name, self.base_vfs)

  def xOpen(self, fname, flags):
    # fname is of type apsw.URIFilename object
    truxton_guid = os.path.basename(fname.filename())
    opened_file = self.Truxton.getfileid(truxton_guid)
    return TruxtonVFSFile(f = opened_file, name = truxton_guid, flags = flags)

  def xAccess(self, pathname, flags):
    return False
  
  def xDelete(self, filename, syncdir):
    pass
    
class TruxtonVFSFile(apsw.VFSFile):
    def __init__(self, f: truxton.TruxtonFileIO, name, flags):
        """
        Truxton VFS File object

        Args:
          * f: TruxtonFileIO object returned by Truxton.getfileid
          * name: name of the file
          * flags: SQLite open flags
        """

        self.f = f
        self.flags = flags
        self.name = name
        self.mode = "rb"

    def xRead(self, amount, offset) -> bytes:
        self.f.seek(offset)
        data = self.f.read(amount)
        return data

    def xFileControl(self, *args):
        return True

    def xDeviceCharacteristics(self):
        return 4096

    def xCheckReservedLock(self):
        return False

    def xLock(self, level):
        pass

    def xUnlock(self, level):
        pass

    def xSectorSize(self):
        return self.f.block_size

    def xClose(self):
        self.f.close()
        pass

    def xFileSize(self):
        pos = self.f.tell()
        self.f.seek(0, 2)
        size = self.f.tell()
        self.f.seek(pos)
        return size

    def xSync(self, flags):
        pass

    def xTruncate(self, newsize):
        pass

    def xWrite(self, data, offset):
        pass

if __name__ == "__main__":
  sys.exit(main())