DataFlex

Read Text from a Remote SFTP File (Sequential)

Demonstrates the Chilkat SFtp.ReadFileText method, which reads up to a number of bytes from the current position of an open handle and decodes them to text. The arguments are the handle, the maximum number of bytes, and the charset. This example reads in chunks until end-of-file.

Background: Reading a file in bounded chunks keeps memory use predictable regardless of file size, which is why the loop reads a fixed amount and repeats until Eof. A subtlety worth knowing: the byte limit is applied to the encoded bytes, so a chunk boundary could in principle fall in the middle of a multibyte character — accumulating the pieces and decoding the whole avoids any such issue in practice here since the text is reassembled in a StringBuilder.

Chilkat DataFlex Downloads

Download Chilkat for DataFlex

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSftp
    Integer iPort
    String sPassword
    String sHandle
    Handle hoSbContent
    Integer iChunkSize
    Boolean iReading
    String sChunk
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    //  Demonstrates the SFtp.ReadFileText method, which reads up to a number of bytes from the current
    //  position of an open handle and decodes them to text.  The 1st argument is the handle, the 2nd
    //  is the maximum number of bytes, and the 3rd is the charset.

    Get Create (RefClass(cComChilkatSFtp)) To hoSftp
    If (Not(IsComObjectCreated(hoSftp))) Begin
        Send CreateComObject of hoSftp
    End

    //  Connect, authenticate, and initialize the SFTP subsystem.
    Move 22 To iPort
    Get ComConnect Of hoSftp "sftp.example.com" iPort To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Normally you would not hard-code the password in source.  You should instead obtain it
    //  from an interactive prompt, environment variable, or a secrets vault.
    Move "mySshPassword" To sPassword

    Get ComAuthenticatePw Of hoSftp "mySshLogin" sPassword To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComInitializeSftp Of hoSftp To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Open the remote file for reading.
    Get ComOpenFile Of hoSftp "subdir/notes.txt" "readOnly" "openExisting" To sHandle
    Get ComLastMethodSuccess Of hoSftp To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Read the file in chunks until end-of-file, accumulating the text.
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbContent
    If (Not(IsComObjectCreated(hoSbContent))) Begin
        Send CreateComObject of hoSbContent
    End
    Move 4096 To iChunkSize
    Move True To iReading
    While iReading
        Get ComReadFileText Of hoSftp sHandle iChunkSize "utf-8" To sChunk
        Get ComLastReadFailed Of hoSftp sHandle To bTemp1
        If (bTemp1) Begin
            Get ComLastErrorText Of hoSftp To sTemp1
            Showln sTemp1
            Procedure_Return
        End

        Get ComAppend Of hoSbContent sChunk To iSuccess

        //  Stop once the end of the file has been reached.
        Get ComEof Of hoSftp sHandle To bTemp1
        Move (Not bTemp1) To iReading
    Loop

    Get ComCloseHandle Of hoSftp sHandle To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetAsString Of hoSbContent To sTemp1
    Showln sTemp1

    Send ComDisconnect To hoSftp


End_Procedure