ctree data

[Carl K]

A friend needs to convert c-tree plus data to MySql. I can to the "to MySql
part, but need some help with the "from c-tree." If I just wanted to get this
done, I would hunt down the ODBC driver and use some MSy thing. But I am trying
to hone my Python skills, but right now I am in over my head, thus this post. I
think with a little boost I will be able to make it all come together. (well,
little boost may be an understatement - I have no clue how close/far I am from
what I need.)

My searching around has come up with a few ways to use Python to read the data:

1. pull what I need from some other py code that uses c-tree:

http://oltp-platform.cvs.sourceforg...es/PythonScript/PythonTranslate.h?view=markup
http://oltp-platform.cvs.sourceforge.net/oltp-platform/OLTPP/scripts/TestZipCodes.py?view=markup

12 a,b,c = ZipCode.Get()
13 print "Zip code is ", a
14 print "State is ", b
15 print "City is ", c

I am sure this is what I want. I just haven't figured out where to start.

2. "Pyrex" to create Python bindings to C API with minimal C knowledge. I took
C and did a few little utilities on my own in the 90's. plus I can make a
tarball. today I am not sure I even qualify for "minimal."

3. the C API is present as a shared object (.so), use it from Python with
ctypes. I have no idea what that means.

4. odbc - I am actually not thrilled about using the ctree odbc driver in any
environment, because someone else who tried to use it on some other data a few
years ago said it was flaky, and support was next to useless.

5, get someone who knows perl to do it using
http://cpan.uwinnipeg.ca/htdocs/Db-Ctree/Db/Ctree.html - This just shows what
lengths I am willing to go to. but I really don't want to start learning perl.

TIA
Carl K

 

[Terry Reedy]

|A friend needs to convert c-tree plus data to MySql. I can to the "to
MySql
| part, but need some help with the "from c-tree." If I just wanted to get
this
| done, I would hunt down the ODBC driver and use some MSy thing. But I am
trying
| to hone my Python skills,
| My searching around has come up with a few ways to use Python to read the
data:
|
| 1. pull what I need from some other py code that uses c-tree:
|
|
http://oltp-platform.cvs.sourceforg...es/PythonScript/PythonTranslate.h?view=markup
|
http://oltp-platform.cvs.sourceforge.net/oltp-platform/OLTPP/scripts/TestZipCodes.py?view=markup
|
| 12 a,b,c = ZipCode.Get()
| 13 print "Zip code is ", a
| 14 print "State is ", b
| 15 print "City is ", c
|
| I am sure this is what I want. I just haven't figured out where to
start.
|
| 2. "Pyrex" to create Python bindings to C API with minimal C knowledge.
I took
| C and did a few little utilities on my own in the 90's. plus I can make
a
| tarball. today I am not sure I even qualify for "minimal."
|
| 3. the C API is present as a shared object (.so), use it from Python with
| ctypes. I have no idea what that means.
[snip]

I personally would start with either 1 or 3, but probably 3 since the skill
of using ctypes is transferable to other problems and I want to learn it
anyway. Ctypes is a foreign function interface (FFI) module. It is new in
the Python stdlib with 2.5 but has been around as a 3rd party module much
longer. With a specification of the C API in hand, you should be able to
write Python functions that call functions in the shared library. Ctypes
handles the interconversion of Python and C datatypes and the calling
details.

I would start with the simplest thing that you can verify working: open
database, get some info that you can print, so you know you really opened
it, and close database.

Terry Jan Reedy

 

[John Machin]

A friend needs to convert c-tree plus data to MySql. I can to the "to MySql
part, but need some help with the "from c-tree." If I just wanted to get this
done, I would hunt down the ODBC driver and use some MSy thing. But I am trying
to hone my Python skills, but right now I am in over my head, thus this post. I
think with a little boost I will be able to make it all come together. (well,
little boost may be an understatement - I have no clue how close/far I am from
what I need.)

My searching around has come up with a few ways to use Python to read the data:

1. pull what I need from some other py code that uses c-tree:

http://oltp-platform.cvs.sourceforg....sourceforge.net/oltp-platform/OLTPP/scripts/...

12 a,b,c = ZipCode.Get()
13 print "Zip code is ", a
14 print "State is ", b
15 print "City is ", c

I am sure this is what I want. I just haven't figured out where to start.

2. "Pyrex" to create Python bindings to C API with minimal C knowledge. I took
C and did a few little utilities on my own in the 90's. plus I can make a
tarball. today I am not sure I even qualify for "minimal."

3. the C API is present as a shared object (.so), use it from Python with
ctypes. I have no idea what that means.

4. odbc - I am actually not thrilled about using the ctree odbc driver in any
environment, because someone else who tried to use it on some other data a few
years ago said it was flaky, and support was next to useless.

5, get someone who knows perl to do it usinghttp://cpan.uwinnipeg.ca/htdocs/Db-Ctree/Db/Ctree.html- This just shows what
lengths I am willing to go to. but I really don't want to start learning perl.

Possible option 6: Find out if there is (a) a ctree utility program
that dumps a ctree table to a flat file in documented easily-parsed
format plus (b) a method of getting the metadata for each column
(type, decimal places, etc) if that info is not already available from
(a).

It's entirely possible that SQL "select * from the_table" will do (a)
for you, if the output is given with full precision, and there's a
method of getting the columns delimited properly.

HTH,
John