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3240 :: noob confusion stream of conciousness

• bkerin (orginal) [2017-10-11T09:14:24+02:00] view original

  Enjoying the heck out of nim so far.

  In case it's useful for documentation or anything...

  So I want to use db, but it seems db_sqlite doesn't really offer prepared statements (though it uses them internally), so I dip down into sqlite3. A few hours for total noob to have prepared statement working, not bad. Here's what caused bother/confusion along the way:

  • Sources could be more cross linked, i.e. types between pages, sources to each other etc. Quite a lot of flipping between db_sqlite, sqlite3, and db_common. Took a google to find db_common because for some reason it doesn't show up on modules page. db_common seems maybe mis-named as it appears to have some SQL-specific stuff, though maybe its more generally useful I don't know.
  • Reinvented dbError due to stupidity, which was a bit painful because I couldn't figure out how to make a string from a cstring. After some stack exchange I ended up with toString like so:

  import sequtils
  
  proc toString(str: seq[char]): string =
    result = newStringOfCap(len(str))
    for ch in str:
      add(result, ch)
  
  proc dbErrExcept(): ref Exception =
    var escs: cstring = db.errmsg
    var es = toString(toSeq(escs.items))
    result = newException(Exception, es)
  Run

  It seemed like there must be an easier way to go cstring -> string but it took a long time to realize it was $ operator. Not sure what might be done to make realizing this more likely, maybe it's all me.

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• Tiberium (orginal) [2017-10-11T12:45:58+02:00] view original

  About toString - in Nim $ is used as a stringify operator for almost all types anywhere (not only in stdlib). So you should firstly try $ on a type you want to convert to string :)

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• jlp765 (orginal) [2017-10-12T01:54:35+02:00] view original

  SqLite is written in C

  SqLite therefore uses cstring

  Don't bother with seq[char], just use cstring which Nim easily converts to string

  ---

  Why not copy what db_sqlite has done, and have your own setupQuery() which calls SqLite's prepare_v2()

  then you can

  
  var stmt = setupQuery(db, query, args)
  # now step thru the stmt to iterate thru rows of data
  Run

  but don't let me stop you doing things the hard way ;-)

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• cdunn2001 (orginal) [2017-10-12T07:05:28+02:00] view original

  When I have a question on how to do something in Nim, I often search Rosetta Code.

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