DataFlex

Chilkat Zip API Concepts

See more Zip Examples

This example demonstrates several core concepts of the Chilkat.Zip class, including how ZIP entries are added, managed, and transformed as a ZIP archive progresses from an in-memory staging object to an actual written .zip file.

The example shows how to:

• Initialize a new ZIP object using NewZip
• Add filesystem file references using AddFile
• Add in-memory text data using AddString
• Modify the stored ZIP filename independently of the source filesystem filename
• Examine ZIP entries before and after writing the ZIP archive
• Understand how ZIP entry types change during the ZIP lifecycle

The example also demonstrates the meaning of the different ZipEntry.EntryType values:

• 1 — File Entry: A reference to a filesystem file that has not yet been processed
• 2 — Data Entry: An in-memory entry containing text or binary data
• 0 — Mapped Entry: An entry already existing within the currently open ZIP archive

This example is especially useful for understanding that methods such as AddFile and AppendFiles initially add only references to filesystem files, and that the actual file reading and compression occur later when WriteZip or WriteZipAndClose is called.

DataFlex

Use ChilkatAx-win32.pkg

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

    Move False To iSuccess

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

    // ------------------------------------------------------------
    // This example demonstrates some of the fundamental concepts
    // of the Chilkat Zip class.
    // 
    // We will:
    // 
    //   1) Create a new ZIP object
    //   2) Add a filesystem file using AddFile
    //   3) Add an in-memory text entry using AddString
    //   4) Examine the ZIP entries before writing the ZIP
    //   5) Write the ZIP archive
    //   6) Examine how the entry types change after writing
    // 
    // The final ZIP archive will contain:
    // 
    //     helloWorld.txt
    //     HelloWorld2.txt
    // 

    // ------------------------------------------------------------
    // Initialize the Zip object.
    // 
    // NewZip resets the Zip object to a new and empty state.
    // It does NOT immediately create the .zip file.
    // 
    // The filename passed to NewZip becomes the default filename
    // used later when WriteZip or WriteZipAndClose is called.
    Get ComNewZip Of hoZip "test.zip" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoZip To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComFileName Of hoZip To sTemp1
    Showln "ZIP filename = " sTemp1
    Showln ""

    // ------------------------------------------------------------
    // Add a file from the local filesystem.
    // 
    // AddFile does NOT immediately read or compress the file.
    // Instead, it adds a reference to the filesystem file.
    // 
    // The actual file data will be read later when WriteZip
    // or WriteZipAndClose is called.
    // 
    // Note:
    // On Windows, forward slashes are equivalent to backslashes.
    Move False To iSaveExtraPath
    Get ComAddFile Of hoZip "/temp/abc123/HelloWorld123.txt" iSaveExtraPath To iSuccess

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

    // The ZIP object now contains one entry that references
    // the local filesystem file:
    // 
    //     /temp/abc123/HelloWorld123.txt
    // 

    // ------------------------------------------------------------
    // Change the filename that will be stored in the ZIP archive.
    // 
    // The source filesystem file remains:
    // 
    //     /temp/abc123/HelloWorld123.txt
    // 
    // But the ZIP entry will be written as:
    // 
    //     helloWorld.txt
    // 
    Get Create (RefClass(cComChilkatZipEntry)) To hoEntry
    If (Not(IsComObjectCreated(hoEntry))) Begin
        Send CreateComObject of hoEntry
    End
    Get pvComObject of hoEntry to vEntry
    Get ComEntryAt Of hoZip 0 vEntry To iSuccess
    Set ComFileName Of hoEntry To "helloWorld.txt"

    // ------------------------------------------------------------
    // Add another ZIP entry directly from in-memory text data.
    // 
    // This entry does not reference a filesystem file.
    // The text data already exists in memory.
    Get ComAddString Of hoZip "HelloWorld2.txt" "hello world!" "utf-8" To iSuccess

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

    // ------------------------------------------------------------
    // Examine the ZIP entries before writing the ZIP archive.
    // 
    // ZIP entries can have different entry types:
    // 
    // 0 -- Mapped Entry
    //      An entry already existing in an open ZIP archive.
    // 
    // 1 -- File Entry
    //      A reference to a filesystem file that has not yet
    //      been read or compressed.
    // 
    // 2 -- Data Entry
    //      An in-memory entry containing text or binary data.
    // 
    // 3 -- Null Entry
    //      An entry that no longer exists.
    // 
    // 4 -- New Directory Entry
    //      A directory entry added by AddEmpty.
    // 
    // At this point:
    // 
    //   helloWorld.txt    => type 1
    //   HelloWorld2.txt   => type 2
    // 
    Showln "Entries BEFORE writing the ZIP:"
    Showln ""

    Get ComNumEntries Of hoZip To n

    For i From 0 To (n - 1)
        Get pvComObject of hoEntry to vEntry
        Get ComEntryAt Of hoZip i vEntry To iSuccess
        Get ComFileName Of hoEntry To sTemp1
        Get ComEntryType Of hoEntry To iTemp1
        Showln "  " sTemp1 ", type=" iTemp1
    Loop

    Showln ""

    // ------------------------------------------------------------
    // Write the ZIP archive.
    // 
    // During this call:
    // 
    //   * Filesystem file references are read
    //   * Data is compressed as needed
    //   * The .zip file is created and written
    // 
    Get ComWriteZip Of hoZip To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoZip To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // ------------------------------------------------------------
    // Examine the ZIP entries again AFTER writing.
    // 
    // Because we called WriteZip (instead of WriteZipAndClose),
    // the ZIP archive remains open.
    // 
    // The entries are automatically converted to
    // "mapped entries" (type 0), meaning they now point to
    // entries within the currently open ZIP archive.
    // 
    // At this point:
    // 
    //   helloWorld.txt    => type 0
    //   HelloWorld2.txt   => type 0
    // 
    Showln "Entries AFTER writing the ZIP:"
    Showln ""

    Get ComNumEntries Of hoZip To n

    For i From 0 To (n - 1)
        Get pvComObject of hoEntry to vEntry
        Get ComEntryAt Of hoZip i vEntry To iSuccess
        Get ComFileName Of hoEntry To sTemp1
        Get ComEntryType Of hoEntry To iTemp1
        Showln "  " sTemp1 ", type=" iTemp1
    Loop

    Showln ""

    // ------------------------------------------------------------
    // Close the ZIP archive and clear the Zip object.
    Send ComCloseZip To hoZip

    Showln "Done."


End_Procedure