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katyperry wrote: ↑

Wed Oct 01, 2025 9:59 am

Hello everyone, I'm new to LiveCode and want to save data from a field to a text file. I'm not sure which command to use and how to reopen saved data. Can someone share a basic example for me to refer to?

katyperry wrote: ↑

Wed Oct 01, 2025 9:59 am

Hello everyone, I'm new to LiveCode and want to save data from a field to a text file. I'm not sure which command to use and how to reopen saved data. Can someone share a basic example for me to refer to?

“ChatGPT” wrote:
There are a few ways to do file I/O in LiveCode, but the simplest is to use the put ... into URL ("file:...") form.

⸻

Example: Save and Load from a Text File

Suppose you have a field on your card called fld "MyData".

To save the contents of the field to a text file:

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on mouseUp
   -- pick a location and name
   answer file "Save data as:"
   if it is empty then exit mouseUp

   put field "MyData" into URL ("file:" & it)
end mouseUp

To load it back later:

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on mouseUp
   answer file "Choose a file to open:"
   if it is empty then exit mouseUp

   put URL ("file:" & it) into field "MyData"
end mouseUp

What’s happening here:
• answer file shows a standard open/save dialog so the user can pick a file.
• put field "MyData" into URL ("file:" & it) writes the field contents directly to the file.
• put URL ("file:" & it) into field "MyData" reads the file back into the field.

⸻

A fixed-name file (no dialogs)

If you always want to use the same file (say, on desktop):

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 -- Save
put specialFolderPath("desktop") & "/myData.txt" into tFile
put field "MyData" into URL ("file:" & tFile)

-- Load
put specialFolderPath("desktop") & "/myData.txt" into tFile
put URL ("file:" & tFile) into field "MyData"

Here’s the “under-the-hood” way to do file I/O in LiveCode using open file, read, write, and close file. I’ll show save, load, and append patterns, plus basic error handling.

⸻

Save (overwrite) the contents of a field to a text file

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command SaveFieldToFile pFieldName
   -- Pick/save to a file
   answer file "Save data as:"
   if it is empty then exit SaveFieldToFile
   put it into tPath

   -- Open for write (creates or truncates)
   open file tPath for write
   if the result is not empty then
      answer error "Couldn't open file:" && the result
      exit SaveFieldToFile
   end if

   -- Write the text and close
   put field pFieldName into tText
   write tText to file tPath
   close file tPath
end SaveFieldToFile

Load (read) a text file into a field — line by line

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command LoadFileIntoField pFieldName
   answer file "Choose a file to open:"
   if it is empty then exit LoadFileIntoField
   put it into tPath

   open file tPath for read
   if the result is not empty then
      answer error "Couldn't open file:" && the result
      exit LoadFileIntoField
   end if

   put empty into tBuffer
   repeat until eof(tPath)
      read from file tPath for 1 line
      put it after tBuffer
   end repeat

   close file tPath
   put tBuffer into field pFieldName
end LoadFileIntoField

Append a single line to an existing file (or create it)

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command AppendLineToFile pLine
   answer file "Pick a file to append to:"
   if it is empty then exit AppendLineToFile
   put it into tPath

   open file tPath for append
   if the result is not empty then
      answer error "Couldn't open file for append:" && the result
      exit AppendLineToFile
   end if

   write pLine & cr to file tPath
   close file tPath
end AppendLineToFile

Read a file in fixed-size chunks (useful for big files)

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command LoadFileChunked pFieldName
   answer file "Choose a file to open:"
   if it is empty then exit LoadFileChunked
   put it into tPath

   open file tPath for read
   if the result is not empty then
      answer error "Couldn't open file:" && the result
      exit LoadFileChunked
   end if

   put empty into tBuffer
   repeat until eof(tPath)
      read from file tPath for 4096  -- bytes
      put it after tBuffer
   end repeat

   close file tPath
   put tBuffer into field pFieldName
end LoadFileChunked

Read a file in fixed-size chunks (useful for big files)

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command LoadFileChunked pFieldName
   answer file "Choose a file to open:"
   if it is empty then exit LoadFileChunked
   put it into tPath

   open file tPath for read
   if the result is not empty then
      answer error "Couldn't open file:" && the result
      exit LoadFileChunked
   end if

   put empty into tBuffer
   repeat until eof(tPath)
      read from file tPath for 4096  -- bytes
      put it after tBuffer
   end repeat

   close file tPath
   put tBuffer into field pFieldName
end LoadFileChunked

Notes & tips
• Check errors with the result: After open, read, or write, if the result is not empty, an error occurred (e.g., permissions, locked file, bad path).
• Line endings: read ... for 1 line reads up to the next line break; write ... doesn’t add a line break unless you add cr.
• Overwrite vs append:
• open ... for write truncates/creates the file.
• open ... for append writes at the end.
• open ... for read is read-only.
• Binary data: Use the binfile: form with the URL syntax, or still use open file but treat content as bytes. For pure text, the above is fine.
• UTF-8 text: The open/write form writes raw bytes in the engine’s default encoding. If you need UTF-8 reliably, the simplest approach is:

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put textEncode(field "MyData","UTF-8") into tUTF8
put tUTF8 into URL ("file:" & tPath)  -- URL form writes bytes directly

And to read back:

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put URL ("file:" & tPath) into tBytes
put textDecode(tBytes,"UTF-8") into field "MyData"

Common path helpers: specialFolderPath("documents"), specialFolderPath("desktop"), etc.

richmond62 wrote: ↑

Thu Oct 02, 2025 12:35 pm

Maybe the 'real' people in this generation are so lazy, that, not being bothered to take the trouble to find the answers to basic questions, their questions look as if they have been generated by bots.