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datagrid with scrolling text field, linefeeds

Posted: Wed Dec 23, 2009 9:28 am
by jkrische
Hello all...

I've got a rev app I'm working on that displays db data in a table-style datagrid. DB text fields that are intended to contain potentially long prose/notes/etc, which would include linefeeds in the content, are giving me trouble.

In Rev, I can write to the DB just fine, even when my text-to-save contains linefeeds. However, when I try to read the data out and put it into a datagrid, the linefeeds inside the text field are goofing things up. My dg-populating script is interpreting the linefeeds in the text field as a new record, which is not entirely unexpected.

I have tried to use a substitution method, wherein the linefeeds are not stored as such in actuality, but a replacement character set that would almost never come up on its own is used. However, when I try to convert that character set back into linefeeds inside the field's Custom Behavior, I get some really wild results, culminating in a "bad parameter" error in the FillInData behavior.

So, what would be the best way to store & display long db text fields with linefeed-containing data inside a datagrid?

For reference, here are my relevant script bits:

the script which populates the dgData from the DB:

Code: Select all

         if tResultID ="" then
            repeat for each item thisField in myFields
               put "" into notesArray[tNoteCount][thisField]
            end repeat 
            put revDataFromQuery(,,gConID, tSQL) into tResultData
            set the itemdelimiter to tab
            put 0 into n
            repeat for each line thisLine in tResultData
               add 1 to n
               put 0 into i
               repeat for each item thisField in myFields
                  add 1 to i
                  put item i of thisLine into notesArray[n][thisField]
               end repeat
            end repeat
         end if
         set the dgData of group "notes_dglist" to notesArray
the text field's Custom Behavior:

Code: Select all

on FillInData pData
    set the text of field 1 of me to replaceText(pData, "|*|", cr)
end FillInData
Assume that when I write to the DB, I'm doing a replaceText in the other direction, which I know to be working.

Re: datagrid with scrolling text field, linefeeds

Posted: Wed Dec 23, 2009 3:08 pm
by oliverk

I think the problem you are having is due to the revDataFromQuery function, rather than the Data Grid. By default the revDataFromQuery function will return one record per line if i remember correctly.

Because your records span multiple lines, it will be hard to loop through each one. I would do it this way instead (not tested, I just typed this straight out) :

Code: Select all

local tCursor
put revQueryDatabase(gConID, tSQL) into tCursor
if tCursor is not a number then
  answer "Database error: " & tCursor
end if

local tArray
put createOrderedArrayFromCursor(tCursor) into tArray
revCloseCursor tCursor

set the dgData of group "notes_dglist" to tArray
You'll notice that i've used a function called createOrderedArrayFromCursor. This is an operation that comes up very frequently for me, so I abstract this into a function
to prevent doing it again and again. The implementation for the function is here:

Code: Select all

function createOrderedArrayFromCursor pCursor
  local tColumnNames
  put revDatabaseColumnNames(pCursor) into tColumnNames

  local tRecordNumber
  put 1 into tRecordNumber
  local tResult, tRow
  repeat until revQueryIsAtEnd(pCursor)
    repeat for each item tColumn in tColumnNames
       local tValue 
       get revDatabaseColumnNamed (pCursor, tColumn, "tValue")
       put tValue into tRow[tColumn]
    end repeat
    put tRow into tResult[tRecordNumber]
    revMoveToNextRecord pCursor
    add 1 to tRecordNumber
  end repeat
  return tResult
end createOrderedArrayFromCursor
Hope this is some help, you may need to tweak it to get it working properly for your application


Re: datagrid with scrolling text field, linefeeds

Posted: Wed Dec 23, 2009 5:26 pm
by jkrische
Thanks Oliver!

I kept working at it before your reply came in and figured out that the idea on using a short substitution character block was sound, the problem was the particular characters I chose. Apparently "|*|" means something special and was throwing things off. When I made the substitution something like "QQQ", everything worked perfectly. Given the "bad parameter" error I was getting I knew one of the 3 params sent to replaceText was something it didn't like, and the other 2 were things that couldn't change, so that left only one possibility. So then, what's the special meaning of "|*|"? And here I thought it unlikely to be used for anything, silly me.

Of course, the problem is that however unlikely it may be, any substitution character I choose could eventually come up in actual use by somebody, so if I don't have to use it, then why should I, eh? So, I'll definitely be giving your method a shot. Seems easy enough to follow now that I see it written out, should be able to fix any small goofs in it, if there are any (which I doubt, it looks right). Looks a lot like what would be going on under the hood in PHP's mysql_fetch_assoc() function, which I use all the time.

Many thanks again, will give it a shot later on and see how it goes...

Re: datagrid with scrolling text field, linefeeds

Posted: Wed Dec 23, 2009 6:43 pm
by jkrische
Works perfectly, as entered! Future readers of this post can directly use your code and have no issues.

Mega Kudos to Oliver K!