DataFlex

Append Text Data to an Existing ZIP Entry Using ZipEntry.AppendString

See more Zip Examples

This example demonstrates how to use the ZipEntry.AppendString method to append text data to an existing ZIP entry.

The example opens an existing ZIP archive, locates a text file entry, and appends additional text to the end of the file contents.

An important concept demonstrated by this example is that appending data to a ZIP entry transforms the entry into an in-memory Data Entry (EntryType = 2).

For example:

• If the entry is a mapped entry from an opened ZIP archive (EntryType = 0), the compressed entry is first inflated into memory.
• If the entry is a referenced filesystem file (EntryType = 1), the file contents are first loaded into memory.

The new text is then appended to the uncompressed in-memory data, and the entry becomes a Data Entry.

After the ZIP archive is rewritten, the modified entry again becomes a mapped entry stored within the ZIP archive.

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoZip
    Variant vEntry
    Handle hoEntry
    String sTemp1
    Integer iTemp1

    Move False To iSuccess

    Get Create (RefClass(cComChilkatZip)) To hoZip
    If (Not(IsComObjectCreated(hoZip))) Begin
        Send CreateComObject of hoZip
    End

    // ------------------------------------------------------------
    // Open an existing ZIP archive.
    Get ComOpenZip Of hoZip "c:/temp/notes.zip" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoZip To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Locate a text file entry within the ZIP archive.
    Get Create (RefClass(cComChilkatZipEntry)) To hoEntry
    If (Not(IsComObjectCreated(hoEntry))) Begin
        Send CreateComObject of hoEntry
    End

    Get pvComObject of hoEntry to vEntry
    Get ComEntryOf Of hoZip "notes/readme.txt" vEntry To iSuccess

    If (iSuccess <> False) Begin

        // --------------------------------------------------------
        // At this point, the entry is a mapped entry because it
        // originates from an opened ZIP archive.
        // 
        //     EntryType = 0
        // 
        Get ComEntryType Of hoEntry To iTemp1
        Showln "Initial EntryType = " iTemp1

        // Append additional text to the ZIP entry.
        // 
        // The existing compressed ZIP entry is first inflated
        // into memory. The new text is then appended.
        // 
        // After AppendString is called, the entry becomes
        // an in-memory Data Entry:
        // 
        //     EntryType = 2
        // 
        Get ComAppendString Of hoEntry (character(13)) + (character(10)) + "Additional notes added later." "utf-8" To iSuccess

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

        Get ComEntryType Of hoEntry To iTemp1
        Showln "EntryType after AppendString = " iTemp1

        // --------------------------------------------------------
        // Write the modified ZIP archive to a different file.
        // 
        // Changing zip.FileName causes the ZIP archive to be
        // written to a new output file rather than overwriting
        // the original ZIP archive.
        // 
        Set ComFileName Of hoZip To "qa_output/updatedExample.zip"

        // Rewrite the ZIP archive.
        // 
        // The modified in-memory entry is compressed and written
        // into the new ZIP archive.
        // 
        Get ComWriteZip Of hoZip To iSuccess
        If (iSuccess = False) Begin
            Get ComLastErrorText Of hoZip To sTemp1
            Showln sTemp1
            Procedure_Return
        End

        // After rewriting the ZIP archive, the entry again becomes
        // a mapped entry:
        // 
        //     EntryType = 0
        // 
        Get ComEntryType Of hoEntry To iTemp1
        Showln "EntryType after WriteZip = " iTemp1
    End

    Send ComCloseZip To hoZip

    Showln "ZIP entry updated successfully."


End_Procedure