(PowerShell) Understanding ZIP Entry Types and the ZIP Object Lifecycle

See more Zip Examples

This example demonstrates how the Chilkat.Zip object manages entries before and after a ZIP archive is written.

The example shows:

• How file references are added from the local filesystem using AppendFilesEx
• How in-memory entries are added using AddString
• How ZIP entry types change as the ZIP archive progresses from an in-memory staging object to an actual written .zip file
• How additional entries can continue to be added even after the ZIP archive has already been written

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

• 1 — File references in the local filesystem that have not yet been processed
• 2 — In-memory data entries
• 0 — Entries mapped to an existing open ZIP archive

This example is useful for understanding how the Chilkat.Zip class internally stages entries prior to writing the final ZIP archive.

Note: This example requires Chilkat v11.0.0 or greater.

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Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

$success = $false

$zip = New-Object Chilkat.Zip

$zipPath = "c:/temp/out.zip"

# Start a new Zip object and set the output path.
# This does not create the .zip file yet.  It only initializes the Zip object
# and records the filename to be used later when WriteZip is called.
$zip.NewZip($zipPath)

# Add references to files in the local filesystem.
# AppendFilesEx does not read, compress, or store the file contents at this point.
# It only adds file references to the Zip object.  The referenced files are
# read and compressed later, when WriteZip is called.
$recurse = $true
$saveExtraPath = $false
$archiveOnly = $false
$includeHidden = $true
$includeSystem = $false
$success = $zip.AppendFilesEx("c:/temp/files_to_zip",$recurse,$saveExtraPath,$archiveOnly,$includeHidden,$includeSystem)
if ($success -eq $false) {
    $($zip.LastErrorText)
    exit
}

# We can inspect the entries that have been added to the Zip object.
# At this stage, the entries are still references to files in the local filesystem.
$entry = New-Object Chilkat.ZipEntry
$count = $zip.NumEntries
$i = 0
while ($i -lt $count) {
    $zip.EntryAt($i,$entry)
    $($entry.FileName + " entryType = " + $entry.EntryType)
    $i = $i + 1
}

$("----")

# Sample output for the above loop:
# 
# hamlet.xml entryType = 1
# hello.pdf entryType = 1
# ...
# ...
# 
# entryType = 1 means "File Entry".
# A File Entry is a reference to a file in the local filesystem.
# The file data has not yet been read into the Zip object.
# 
# Possible entryType values:
# 
# 0 - Mapped Entry:
#     An entry that already exists in an open .zip file.
# 
# 1 - File Entry:
#     A file in the local filesystem that has been referenced, but not yet
#     read or compressed.  These entries are added by methods such as
#     AppendFiles, AppendFilesEx, and AddFile.
# 
# 2 - Data Entry:
#     An entry containing uncompressed data already held in memory.
#     These entries are added by methods such as AddData, AddString,
#     AddSb, AddBd, and AddEncoded.
# 
# 3 - Null Entry:
#     An entry that no longer exists in the .zip.
# 
# 4 - New Directory Entry:
#     A directory entry added by calling AddEmpty.

# Additional entries can still be added before the .zip is written.
# This entry is created from an in-memory string, so it is a Data Entry
# rather than a File Entry.
$zip.AddString("helloWorld.txt","Hello World","utf-8")

# Inspect the Zip object again before writing.
# The file references are still entryType = 1.
# The in-memory string entry is entryType = 2.
$count = $zip.NumEntries
$i = 0
while ($i -lt $count) {
    $zip.EntryAt($i,$entry)
    $($entry.FileName + " entryType = " + $entry.EntryType)
    $i = $i + 1
}

$("----")

# Sample output:
# 
# hamlet.xml entryType = 1
# hello.pdf entryType = 1
# ...
# ...
# helloWorld.txt entryType = 2
# 
# helloWorld.txt has entryType = 2 because its contents came from memory.
# It is not a reference to a file in the local filesystem.

# ----------------------------------------------------------------------------
# Write the Zip object to the .zip file.
# 
# During this call, Chilkat reads the referenced files from the local filesystem,
# compresses the data as needed, and writes the final .zip archive.
$zip.FileName = $zipPath
$success = $zip.WriteZip()
if ($success -eq $false) {
    $($zip.LastErrorText)
    exit
}

# After WriteZip returns successfully, the .zip file is written and remains
# open in the Zip object.  The entries now correspond to entries in the
# currently open .zip archive.
$count = $zip.NumEntries
$i = 0
while ($i -lt $count) {
    $zip.EntryAt($i,$entry)
    $($entry.FileName + " entryType = " + $entry.EntryType)
    $i = $i + 1
}

$("----")

# Sample output:
# 
# hamlet.xml entryType = 0
# hello.pdf entryType = 0
# ...
# ...
# helloWorld.txt entryType = 0
# 
# entryType = 0 means "Mapped Entry".
# A Mapped Entry is an entry that exists in an open .zip file.

# ----------------------------------------------------------------------------
# The .zip remains open after WriteZip, so additional entries can still be added.
# 
# This adds another in-memory string entry to the currently open Zip object.
$zip.AddString("helloWorld2.txt","Hello World 2","utf-8")

# Write the .zip again to include the newly added entry.
$success = $zip.WriteZip()
if ($success -eq $false) {
    $($zip.LastErrorText)
    exit
}

# Inspect the entries one final time.
# After the second WriteZip, the new entry is also mapped to the open .zip file.
$count = $zip.NumEntries
$i = 0
while ($i -lt $count) {
    $zip.EntryAt($i,$entry)
    $($entry.FileName + " entryType = " + $entry.EntryType)
    $i = $i + 1
}

$("----")

# Sample output:
# 
# hamlet.xml entryType = 0
# hello.pdf entryType = 0
# ...
# ...
# helloWorld.txt entryType = 0
# helloWorld2.txt entryType = 0

# Close the open .zip archive and clear the Zip object.
$zip.CloseZip()

$("Success")