Cache Delphi ActiveX Reference Documentation

TChilkatCache

Current Version: 10.1.2

Importing the Chilkat ActiveX into Delphi

Important: When upgrading to a new version of Chilkat, make sure to re-imported ActiveX DLL into Delphi to regenerate the files described below.


Chilkat v9.5.*: If using Chilkat v9.5.*, then use "Chilkat_v9_5_0_TLB" instead of "Chilkat_TLB", and the DLLs are named ChilkatAx-9.5.0-win32.dll (or ChilkatAx-9.5.0-x64.dll).


Two things are required to use an ActiveX in Delphi:

  1. The ActiveX DLL needs to be registered via regsvr32 on the system where the Delphi application runs. See How To Register ActiveX DLLs for detailed information.
  2. See also: ActiveX Registration Tutorial
  3. The ActiveX component needs to be "imported". Use the Delphi Import Component Wizard to import the Chilkat type library. This creates the following files: Chilkat_TLB.pas and Chilkat_TLB.dcr. The Chilkat_TLB.pas should be added to your project.

To import the Chilkat type library, do the following:

  1. In the Delphi RAD Studio, select the menu item "Component" --> "Import a Type Library".
  2. Find "Chilkat ActiveX" in the list and select it. This will only appear in the list if the ChilkatAx-win32.dll (or ChilkatAx-x64.dll) has been registered w/ regsvr32.
  3. Check the "Generate Component Wrappers" checkbox.
  4. Select a directory where the unit files (.pas and .dcr) should be generated.
  5. Select "Create Unit" and then "Finish".
  6. Add the .pas to your Delphi project.

To use a Chilkat ActiveX object in your Delphi code, add "Chilkat_TLB" to the "uses" statement. For example:

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

Object Creation

var
obj: TChilkatCache;
...
begin
obj := TChilkatCache.Create(Self);
...
// When finished, free the object instance.
obj.Free();

Properties

DebugLogFilePath
property DebugLogFilePath: WideString

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

  • A timeout property set to 0, indicating an infinite timeout.
  • A hang occurring within an event callback in the application code.
  • An internal bug in the Chilkat code causing the hang.

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LastBinaryResult
property LastBinaryResult: OleVariant readonly

This property is mainly used in SQL Server stored procedures to retrieve binary data from the last method call that returned binary data. It is only accessible if Chilkat.Global.KeepBinaryResult is set to 1. This feature allows for the retrieval of large varbinary results in an SQL Server environment, which has restrictions on returning large data via method calls, though temp tables can handle binary properties.

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LastErrorHtml
property LastErrorHtml: WideString readonly

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorText
property LastErrorText: WideString readonly

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorXml
property LastErrorXml: WideString readonly

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastEtagFetched
property LastEtagFetched: WideString readonly

The ETag of the last item fetched from cache.

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LastExpirationFetchedStr
property LastExpirationFetchedStr: WideString readonly

Expiration date/time of the last item fetched from cache in RFC822 string format.

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LastHitExpired
property LastHitExpired: Integer readonly

1 if the LastExpirationFetched is before the current date/time. Otherwise 0.

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LastKeyFetched
property LastKeyFetched: WideString readonly

The key of the last item fetched from cache. (For web pages, the key is typically the canonicalized URL. Otherwise, the key is a unique identifer used to access the cached item.)

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LastMethodSuccess
property LastMethodSuccess: Integer

Indicates the success or failure of the most recent method call: 1 means success, 0 means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages.

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LastStringResult
property LastStringResult: WideString readonly

In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. It is accessible only when Chilkat.Global.KeepStringResult is set to TRUE. SQL Server has limitations on string lengths returned from methods and properties, but temp tables can be used to access large strings.

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LastStringResultLen
property LastStringResultLen: Integer readonly

The length, in characters, of the string contained in the LastStringResult property.

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Level
property Level: Integer

The number of directory levels in the cache. Possible values are:

0: All cache files are in a single directory (the cache root).

1: Cache files are located in 256 sub-directories numbered 0 .. 255 directly under the cache root.

2: There are two levels of sub-directories under the cache root. The 1st level has 256 sub-directories numbered 0 .. 255 directly under the cache root. The 2nd level allows for up to 256 sub-directories (0..255) under each level-1 directory. Cache files are stored in the leaf directories.

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NumRoots
property NumRoots: Integer readonly

The number of root directories composing the cache. A typical multi-root cache would place each root on a separate hard drive.

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VerboseLogging
property VerboseLogging: Integer

If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
property Version: WideString readonly

Version of the component/library, such as "10.1.0"

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Methods

AddRoot
procedure AddRoot(path: WideString);

Must be called once for each cache root. For example, if the cache is spread across D:\cacheRoot, E:\cacheRoot, and F:\cacheRoot, an application would setup the cache object by calling AddRoot three times -- once with "D:\cacheRoot", once with "E:\cacheRoot", and once with "F:\cacheRoot".

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DeleteAll
function DeleteAll(): Integer;

Deletes all items in the cache. This method completely clears the cache. All files in the cache are deleted. (If the cache is multi-level, existing sub-directories are not deleted.)

Returns the number of items (i.e. cache files) deleted.

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DeleteAllExpired
function DeleteAllExpired(): Integer;

Deletes all expired items from the cache.

Returns the number of items (i.e. cache files) deleted.

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DeleteFromCache
function DeleteFromCache(key: WideString): Integer;

Deletes a single item from the disk cache. Returns 0 if the item exists in cache but could not be deleted. Otherwise returns 1.

Returns 1 for success, 0 for failure.

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DeleteOlderDt
function DeleteOlderDt(dateTime: TCkDateTime): Integer;

The same as DeleteOlder, except the dateTime is passed as a CkDateTime.

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DeleteOlderStr
function DeleteOlderStr(dateTimeStr: WideString): Integer;

The same as DeleteOlder, except the dateTimeStr is passed as a date/time in RFC822 format.

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FetchBd
function FetchBd(key: WideString; bd: TChilkatBinData): Integer;
Introduced in version 9.5.0.91

Fetches an item from cache and returns in bd.

The key may be any length and may include any characters. It should uniquely identify the cached item. (No two items in the cache should have the same key.)

Returns 1 for success, 0 for failure.

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FetchFromCache
function FetchFromCache(key: WideString): OleVariant;

Fetches an item from cache.

The key may be any length and may include any characters. It should uniquely identify the cached item. (No two items in the cache should have the same key.)

Returns a zero-length byte array (as an OleVariant) on failure.
An empty array will have a VarArrayHighBound of -1 meaning 0 elements.

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FetchSb
function FetchSb(key: WideString; sb: TChilkatStringBuilder): Integer;
Introduced in version 9.5.0.91

Fetches a text item from the cache and returns in sb.

The key may be any length and may include any characters. It should uniquely identify the cached item. (No two items in the cache should have the same key.)

Returns 1 for success, 0 for failure.

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FetchText
function FetchText(key: WideString): WideString;

Fetches a text item from the cache and returns it's text content.

The key may be any length and may include any characters. It should uniquely identify the cached item. (No two items in the cache should have the same key.)

Returns a zero-length WideString on failure

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GetEtag
function GetEtag(key: WideString): WideString;

Returns the eTag for an item in the cache.

Returns a zero-length WideString on failure

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GetExpirationDt
function GetExpirationDt(key: WideString): TCkDateTime;

Returns the expiration date/time for an item in the cache as a CkDateTime object.

Returns nil on failure

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GetExpirationStr
function GetExpirationStr(url: WideString): WideString;

Returns the expiration date/time for an item in the cache in RFC822 string format.

Returns a zero-length WideString on failure

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GetFilename
function GetFilename(key: WideString): WideString;

Returns the absolute file path of the cache file associated with the key.

Returns a zero-length WideString on failure

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GetRoot
function GetRoot(index: Integer): WideString;

Returns the directory path of the Nth cache root. (Indexing begins at 0.)

Returns a zero-length WideString on failure

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IsCached
function IsCached(key: WideString): Integer;

Returns 1 if the item is found in the cache, otherwise returns 0.

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SaveTextDt
function SaveTextDt(key: WideString; expireDateTime: TCkDateTime; eTag: WideString; itemTextData: WideString): Integer;

The same as SaveText, except the expire date/time is passed as a CkDateTime object.

Returns 1 for success, 0 for failure.

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SaveTextNoExpire
function SaveTextNoExpire(key: WideString; eTag: WideString; itemTextData: WideString): Integer;

Inserts or replaces an text item in the cache with no expiration date/time. The eTag is optional and may be set to a zero-length string. Applications may use it as a place to save additional information about the cached item.

Returns 1 for success, 0 for failure.

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SaveTextStr
function SaveTextStr(key: WideString; expireDateTime: WideString; eTag: WideString; itemTextData: WideString): Integer;

The same as SaveText, except the expire date/time is passed as a string in RFC822 format.

Returns 1 for success, 0 for failure.

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SaveToCacheDt
function SaveToCacheDt(key: WideString; expireDateTime: TCkDateTime; eTag: WideString; itemData: OleVariant): Integer;

The same as SaveToCache, except the expire date/time is passed as a CkDateTime object.

Returns 1 for success, 0 for failure.

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SaveToCacheNoExpire
function SaveToCacheNoExpire(key: WideString; eTag: WideString; itemData: OleVariant): Integer;

Inserts or replaces an item in the cache. The cached item will have no expiration. The eTag is optional and may be set to a zero-length string. Applications may use it as a place to save additional information about the cached item.

Returns 1 for success, 0 for failure.

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SaveToCacheStr
function SaveToCacheStr(key: WideString; expireDateTime: WideString; eTag: WideString; itemData: OleVariant): Integer;

The same as SaveToCache, except the expire date/time is passed in RFC822 string format.

Returns 1 for success, 0 for failure.

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UpdateExpirationDt
function UpdateExpirationDt(key: WideString; expireDateTime: TCkDateTime): Integer;

The same as UpdateExpiration, except the expireDateTime is passed as a CkDateTime.

Returns 1 for success, 0 for failure.

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UpdateExpirationStr
function UpdateExpirationStr(key: WideString; expireDateTime: WideString): Integer;

The same as UpdateExpiration, except the expireDateTime is passed in RFC822 string format.

Returns 1 for success, 0 for failure.

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