Rss Delphi DLL Reference Documentation

Rss

Current Version: 10.1.0

Represents an RSS document or sub-part of a document such as a channel, image, or item. The RSS API allows one to download, create and modify RSS documents.

Create/Dispose

var
myObject: HCkRss;

begin
myObject := CkRss_Create();

// ...

CkRss_Dispose(myObject);
end;

function CkRss_Create: HCkRss; stdcall;

Creates an instance of the HCkRss object and returns a handle (i.e. a Pointer). The handle is passed in the 1st argument for the functions listed on this page.

procedure CkRss_Dispose(handle: HCkRss); stdcall;

Objects created by calling CkRss_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function.

Properties

DebugLogFilePath

procedure CkRss_getDebugLogFilePath(objHandle: HCkRss; outPropVal: HCkString); stdcall;
procedure CkRss_putDebugLogFilePath(objHandle: HCkRss; newPropVal: PWideChar); stdcall;
function CkRss__debugLogFilePath(objHandle: HCkRss): PWideChar; stdcall;

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
there is an internal problem (bug) in the Chilkat code that causes the hang.

See the notes about PWideChar memory ownership and validity.

More Information and Examples

Example showing how to use DebugLogFilePath.

LastErrorHtml

procedure CkRss_getLastErrorHtml(objHandle: HCkRss; outPropVal: HCkString); stdcall;
function CkRss__lastErrorHtml(objHandle: HCkRss): PWideChar; stdcall;

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

See the notes about PWideChar memory ownership and validity.

LastErrorText

procedure CkRss_getLastErrorText(objHandle: HCkRss; outPropVal: HCkString); stdcall;
function CkRss__lastErrorText(objHandle: HCkRss): PWideChar; stdcall;

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

See the notes about PWideChar memory ownership and validity.

More Information and Examples

Concept of LastErrorText LastErrorText Standard Information

LastErrorXml

procedure CkRss_getLastErrorXml(objHandle: HCkRss; outPropVal: HCkString); stdcall;
function CkRss__lastErrorXml(objHandle: HCkRss): PWideChar; stdcall;

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

See the notes about PWideChar memory ownership and validity.

LastMethodSuccess

function CkRss_getLastMethodSuccess(objHandle: HCkRss): wordbool; stdcall;
procedure CkRss_putLastMethodSuccess(objHandle: HCkRss; newPropVal: wordbool); stdcall;

Indicate whether the last method call succeeded or failed. A value of True indicates success, a value of False indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

Any method that returns a string.
Any method returning a Chilkat object, binary bytes, or a date/time.
Any method returning a standard boolean status value where success = True and failure = False.
Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to True. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

NumChannels

function CkRss_getNumChannels(objHandle: HCkRss): Integer; stdcall;

The number of channels in the RSS document.

NumItems

function CkRss_getNumItems(objHandle: HCkRss): Integer; stdcall;

The number of items in the channel.

VerboseLogging

function CkRss_getVerboseLogging(objHandle: HCkRss): wordbool; stdcall;
procedure CkRss_putVerboseLogging(objHandle: HCkRss; newPropVal: wordbool); stdcall;

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

Version

procedure CkRss_getVersion(objHandle: HCkRss; outPropVal: HCkString); stdcall;
function CkRss__version(objHandle: HCkRss): PWideChar; stdcall;

Version of the component/library, such as "9.5.0.94"

See the notes about PWideChar memory ownership and validity.

More Information and Examples

How to get the Chilkat version at runtime.

Methods

AddNewChannel

function CkRss_AddNewChannel(objHandle: HCkRss): HCkRss; stdcall;

Adds a new channel to the RSS document. Returns the Rss object representing the Channel which can then be edited.

Returns nil on failure

AddNewImage

function CkRss_AddNewImage(objHandle: HCkRss): HCkRss; stdcall;

Adds a new image to the RSS document. Returns the Rss object representing the image, which can then be edited.

Returns nil on failure

AddNewItem

function CkRss_AddNewItem(objHandle: HCkRss): HCkRss; stdcall;

Adds a new Item to an Rss channel. Returns the Rss object representing the item which can then be edited.

Returns nil on failure

DownloadRss

function CkRss_DownloadRss(objHandle: HCkRss;
url: PWideChar): wordbool; stdcall;

Downloads an RSS document from the Internet and populates the Rss object with the contents.

Returns True for success, False for failure.

More Information and Examples

Example: Read RSS Feed

DownloadRssAsync ⁽¹⁾

function CkRss_DownloadRssAsync(objHandle: HCkRss;
url: PWideChar): HCkTask; stdcall;

Creates an asynchronous task to call the DownloadRss method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns nil on failure

GetAttr

function CkRss_GetAttr(objHandle: HCkRss;
    tag: PWideChar;
    attrName: PWideChar;
    outStr: HCkString): wordbool; stdcall;
function CkRss__getAttr(objHandle: HCkRss;
    tag: PWideChar;
    attrName: PWideChar): PWideChar; stdcall;

Returns the value of a sub-element attribute. For example, to get the value of the "isPermaLink" attribute of the "guid" sub-element, call item.GetAttr("guid","isPermaLink").

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

GetChannel

function CkRss_GetChannel(objHandle: HCkRss;
index: Integer): HCkRss; stdcall;

Returns the Nth channel of an RSS document. Usually there is only 1 channel per document, so the index argument should be set to 0.

Returns nil on failure

GetCount

function CkRss_GetCount(objHandle: HCkRss;
tag: PWideChar): Integer; stdcall;

Return the number of sub-elements with a specific tag.

GetDateStr

function CkRss_GetDateStr(objHandle: HCkRss;
    tag: PWideChar;
    outStr: HCkString): wordbool; stdcall;
function CkRss__getDateStr(objHandle: HCkRss;
    tag: PWideChar): PWideChar; stdcall;

The same as GetDate, except the date/time is returned in RFC822 string format.

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

GetImage

function CkRss_GetImage(objHandle: HCkRss): HCkRss; stdcall;

Return the image associated with the channel.

Returns nil on failure

GetInt

function CkRss_GetInt(objHandle: HCkRss;
tag: PWideChar): Integer; stdcall;

Return the value of a numeric sub-element as an integer.

GetItem

function CkRss_GetItem(objHandle: HCkRss;
index: Integer): HCkRss; stdcall;

Return the Nth item of a channel as an RSS object.

Returns nil on failure

GetString

function CkRss_GetString(objHandle: HCkRss;
    tag: PWideChar;
    outStr: HCkString): wordbool; stdcall;
function CkRss__getString(objHandle: HCkRss;
    tag: PWideChar): PWideChar; stdcall;

Return the value of an sub-element as a string.

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

LoadRssFile

function CkRss_LoadRssFile(objHandle: HCkRss;
filePath: PWideChar): wordbool; stdcall;

Load an RSS document from a file.

Returns True for success, False for failure.

LoadRssString

function CkRss_LoadRssString(objHandle: HCkRss;
rssString: PWideChar): wordbool; stdcall;

Loads an RSS feed document from an in-memory string.

Returns True for success, False for failure.

LoadTaskCaller

function CkRss_LoadTaskCaller(objHandle: HCkRss;
task: HCkTask): wordbool; stdcall;

Introduced in version 9.5.0.80

Loads the caller of the task's async method.

Returns True for success, False for failure.

MGetAttr

function CkRss_MGetAttr(objHandle: HCkRss;
    tag: PWideChar;
    index: Integer;
    attrName: PWideChar;
    outStr: HCkString): wordbool; stdcall;
function CkRss__mGetAttr(objHandle: HCkRss;
    tag: PWideChar;
    index: Integer;
    attrName: PWideChar): PWideChar; stdcall;

Get an attribute value for the Nth sub-element having a specific tag. As an example, an RSS item may have several "category" sub-elements. To get the value of the "domain" attribute for the 3rd category, call MGetAttr("category",2,"domain").

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

MGetString

function CkRss_MGetString(objHandle: HCkRss;
    tag: PWideChar;
    index: Integer;
    outStr: HCkString): wordbool; stdcall;
function CkRss__mGetString(objHandle: HCkRss;
    tag: PWideChar;
    index: Integer): PWideChar; stdcall;

Get the value of the Nth occurrence of a sub-element. Indexing begins at 0.

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

MSetAttr

function CkRss_MSetAttr(objHandle: HCkRss;
    tag: PWideChar;
    idx: Integer;
    attrName: PWideChar;
    value: PWideChar): wordbool; stdcall;

Set an attribute on the Nth occurrence of a sub-element.

Returns True for success, False for failure.

MSetString

function CkRss_MSetString(objHandle: HCkRss;
    tag: PWideChar;
    idx: Integer;
    value: PWideChar): wordbool; stdcall;

Set the value of the Nth occurrence of a sub-element. Indexing begins at 0.

Returns True for success, False for failure.

NewRss

procedure CkRss_NewRss(objHandle: HCkRss) stdcall;

Clears the RSS document.

Remove

procedure CkRss_Remove(objHandle: HCkRss;
tag: PWideChar) stdcall;

Removes a sub-element from the RSS document.

SetAttr

procedure CkRss_SetAttr(objHandle: HCkRss;
    tag: PWideChar;
    attrName: PWideChar;
    value: PWideChar) stdcall;

Sets the value of a sub-element attribute.

SetDateNow

procedure CkRss_SetDateNow(objHandle: HCkRss;
tag: PWideChar) stdcall;

Sets the value of a date/time sub-element to the current system date/time.

SetDateStr

procedure CkRss_SetDateStr(objHandle: HCkRss;
tag: PWideChar;
dateTimeStr: PWideChar) stdcall;

The same as SetDate, except the date/time is passed as an RFC822 string.

SetInt

procedure CkRss_SetInt(objHandle: HCkRss;
tag: PWideChar;
value: Integer) stdcall;

Sets the value of an integer sub-element.

SetString

procedure CkRss_SetString(objHandle: HCkRss;
tag: PWideChar;
value: PWideChar) stdcall;

Sets the value of a sub-element.

ToXmlString

function CkRss_ToXmlString(objHandle: HCkRss;
outStr: HCkString): wordbool; stdcall;
function CkRss__toXmlString(objHandle: HCkRss): PWideChar; stdcall;

Returns the RSS document as an XML string.

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

Events

Chilkat supports event callbacks for the Delphi DLL starting in version 9.5.0.82.

AbortCheck

function MyAbortCheck(): Integer; cdecl;

Introduced in version 9.5.0.82

Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200. Return True to abort; return False to continue (not abort)

More Information and Examples

Delphi DLL AbortCheck Event Callback Example

PercentDone

function MyPercentDone(pctDone: Integer): Integer; cdecl;

Introduced in version 9.5.0.82

Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).

The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.

Return True to abort; return False to continue (not abort)

More Information and Examples

Delphi DLL PercentDone Event Callback Example

ProgressInfo

procedure MyProgressInfo(name: PWideChar; value: PWideChar) cdecl;

Introduced in version 9.5.0.82

A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.

More Information and Examples

Delphi DLL ProgressInfo Event Callback Example

TaskCompleted

procedure MyTaskCompleted(task: HCkTask) cdecl;

Introduced in version 9.5.0.82

Called in the background thread when an asynchronous task completes.

More Information and Examples

Delphi DLL TaskCompleted Event Callback Example

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