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Sqlite: Bug related to the difference in interpretation of the NIL between Lua and Hollywood.
Posted: Mon Jun 15, 2020 11:11 pm
by obiwan73
Hi Andreas,
When importing a database from a small local library. I found a slight bug related to the different logical interpretation between LUA and Hollywood.
Sqlite: Bug related to the difference in interpretation of the NIL between Lua and Hollywood.
In case a field in a database has a Null value (Permitted in SQL), Lua perceives it/transforms it into a NIL(LUA)
Hollywood receives the NIL value and turns into a NIL (Hollywood) which destroys the variable it affects, giving an error that the variable does not exist.
Lua and Hollywood therefore behave differently. (Tested on WIN/LINUX and LUA)
Code: Select all
/* Test Code Hollywood*/
@require "sqlite3"
local db = sqlite3.open("Database/MundoBIB.db")
for row in db:nrows("SELECT * FROM boeken")
debugprint(row["ID_LIVRE"].." : "..row["TITRE_LIVRE"])
next
WaitLeftMouse
Re: Sqlite: Bug related to the difference in interpretation of the NIL between Lua and Hollywood.
Posted: Tue Jun 16, 2020 12:11 am
by SamuraiCrow
That's a known behavior. Us the
IsNil() function instead of comparing it to NIL the constant.
https://hollywood-mal.com/docs/html/hol ... peNil.html
Re: Sqlite: Bug related to the difference in interpretation of the NIL between Lua and Hollywood.
Posted: Tue Jun 16, 2020 1:03 pm
by obiwan73
Thank you SamuraiCrow for your reaction here and elsewhere
I had already tried this solution but if you use
IsNil() or
GetType(), it doesn't work.
Code: Select all
DebugPrint(row["ID_LIVRE"].." : "..IsNil(row["TITRE_LIVRE"]))
DebugPrint(row["ID_LIVRE"].." : "..GetType(row["TITRE_LIVRE"]))
(Console Output)
....
5710 : 0
5710 : 3
5711 : 0
5711 : 3
The following message arrives for line 5712, I get this error message here.
Error in line 4 (main.hws): Table field "TITRE_LIVRE" was not initialized!
Re: Sqlite: Bug related to the difference in interpretation of the NIL between Lua and Hollywood.
Posted: Tue Jun 16, 2020 10:22 pm
by airsoftsoftwair
What about
HaveItem()? Like so:
Code: Select all
If HaveItem(row, "TITRE_LIVRE")
...
EndIf
Re: Sqlite: Bug related to the difference in interpretation of the NIL between Lua and Hollywood.
Posted: Wed Jun 17, 2020 3:49 am
by obiwan73
Hi Andreas,
It's very strange, the result for row is always zero.
Code: Select all
test={}
test.pi = 3.14
test.nothing = {}
/* Simple Test for HaveItem())*/
DebugPrint("PI: " .. HaveItem(test,"pi") .." - nothing: ".. HaveItem(test, "nothing").." - Keyboard random: ".. HaveItem(test, "hkjhfjkshfj"))
/*reality check */
For row In db:nrows("SELECT * FROM boeken")
DebugPrint(row["ID_LIVRE"]..":" .. HaveItem(row,"ID_LIVRE") .."-".. HaveItem(row, "TITRE_LIVRE"))
Next
PI: 1 - nothing: 1 - Keyboard random: 0
OUTPUT FOR DebugPrint(row["ID_LIVRE"]..":" .. HaveItem(row,"ID_LIVRE") .."-".. HaveItem(row, "TITRE_LIVRE")....
4547:0-0
4548:0-0
4549:0-0
4550:0-0
4551:0-0
4552:0-0
.....
It's very strange, the result for row is always zero.
Re: Sqlite: Bug related to the difference in interpretation of the NIL between Lua and Hollywood.
Posted: Wed Jun 17, 2020 6:27 am
by SamuraiCrow
@obiwan73
Probably because
HaveItem() is returning False if the row is Nil.
Re: Sqlite: Bug related to the difference in interpretation of the NIL between Lua and Hollywood.
Posted: Wed Jun 17, 2020 9:32 am
by obiwan73
In the case of my example here, he's not nil.
gives me the value 4547
But on the same line and the same variable with HaveItem commando gives me zero for
Code: Select all
DebugPrint(HaveItem(row,"ID_LIVRE"))
The good news is that this command I learned is useful to see if a variable in a table exists, I'm testing it at the beginning of the program with the following code.
Code: Select all
test={}
test.pi = 3.14
test.nothing = {}
And the result is correct. But strangely not with my row built with the db:nrows method.
If I do
Code: Select all
If HaveItem(row, "ID_LIVRE")
...
EndIf
I don't have any results because it's always 0 so no treatment in any case.
Re: Sqlite: Bug related to the difference in interpretation of the NIL between Lua and Hollywood.
Posted: Sat Jun 20, 2020 1:44 pm
by airsoftsoftwair
I think the problem is that you're passing an upper-case string to
HaveItem(). Hollywood will always convert table indices to lower case, except when using string indices. So...
Code: Select all
If HaveItem(row, "id_livre")
...
EndIf
...should give you the right result.
See also here:
viewtopic.php?p=5367#p5367