CkRssW Unicode C++ Reference Documentation

CkRssW

Current Version: 10.0.0

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.

Object Creation

// Local variable on the stack
CkRssW obj;

// Dynamically allocate/delete
CkRssW *pObj = new CkRssW();
// ...
delete pObj;

Properties

DebugLogFilePath

void get_DebugLogFilePath(CkString &str);
const wchar_t *debugLogFilePath(void);
void put_DebugLogFilePath(const wchar_t *str);

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.

More Information and Examples

Example showing how to use DebugLogFilePath.

LastErrorHtml

void get_LastErrorHtml(CkString &str);
const wchar_t *lastErrorHtml(void);

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.

LastErrorText

void get_LastErrorText(CkString &str);
const wchar_t *lastErrorText(void);

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.

More Information and Examples

Concept of LastErrorText LastErrorText Standard Information

LastErrorXml

void get_LastErrorXml(CkString &str);
const wchar_t *lastErrorXml(void);

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.

LastMethodSuccess

bool get_LastMethodSuccess(void);
void put_LastMethodSuccess(bool newVal);

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

int get_NumChannels(void);

The number of channels in the RSS document.

NumItems

int get_NumItems(void);

The number of items in the channel.

VerboseLogging

bool get_VerboseLogging(void);
void put_VerboseLogging(bool newVal);

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

void get_Version(CkString &str);
const wchar_t *version(void);

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

More Information and Examples

How to get the Chilkat version at runtime.

Methods

AddNewChannel

CkRssW *AddNewChannel(void);

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

Note: The application is responsible for deleting (via the C++ delete operator) the object returned by this method.

Returns NULL on failure

AddNewImage

CkRssW *AddNewImage(void);

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

Note: The application is responsible for deleting (via the C++ delete operator) the object returned by this method.

Returns NULL on failure

AddNewItem

CkRssW *AddNewItem(void);

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

Note: The application is responsible for deleting (via the C++ delete operator) the object returned by this method.

Returns NULL on failure

DownloadRss

bool DownloadRss(const wchar_t *url);

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⁾

CkTaskW *DownloadRssAsync(const wchar_t *url);

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.

Note: The application is responsible for deleting (via the C++ delete operator) the object returned by this method.

Returns NULL on failure

GetAttr

bool GetAttr(const wchar_t *tag, const wchar_t *attrName, CkString &outStr);
const wchar_t *getAttr(const wchar_t *tag, const wchar_t *attrName);

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.

GetChannel

CkRssW *GetChannel(int index);

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.

Note: The application is responsible for deleting (via the C++ delete operator) the object returned by this method.

Returns NULL on failure

GetCount

int GetCount(const wchar_t *tag);

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

GetDateStr

bool GetDateStr(const wchar_t *tag, CkString &outStr);
const wchar_t *getDateStr(const wchar_t *tag);

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

Returns true for success, false for failure.

GetImage

CkRssW *GetImage(void);

Return the image associated with the channel.

Note: The application is responsible for deleting (via the C++ delete operator) the object returned by this method.

Returns NULL on failure

GetInt

int GetInt(const wchar_t *tag);

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

GetItem

CkRssW *GetItem(int index);

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

Note: The application is responsible for deleting (via the C++ delete operator) the object returned by this method.

Returns NULL on failure

GetString

bool GetString(const wchar_t *tag, CkString &outStr);
const wchar_t *getString(const wchar_t *tag);

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

Returns true for success, false for failure.

LoadRssFile

bool LoadRssFile(const wchar_t *filePath);

Load an RSS document from a file.

Returns true for success, false for failure.

LoadRssString

bool LoadRssString(const wchar_t *rssString);

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

Returns true for success, false for failure.

LoadTaskCaller

bool LoadTaskCaller(CkTaskW &task);

Introduced in version 9.5.0.80

Loads the caller of the task's async method.

Returns true for success, false for failure.

MGetAttr

bool MGetAttr(const wchar_t *tag, int index, const wchar_t *attrName, CkString &outStr);
const wchar_t *mGetAttr(const wchar_t *tag, int index, const wchar_t *attrName);

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.

MGetString

bool MGetString(const wchar_t *tag, int index, CkString &outStr);
const wchar_t *mGetString(const wchar_t *tag, int index);

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

Returns true for success, false for failure.

MSetAttr

bool MSetAttr(const wchar_t *tag, int idx, const wchar_t *attrName, const wchar_t *value);

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

Returns true for success, false for failure.

MSetString

bool MSetString(const wchar_t *tag, int idx, const wchar_t *value);

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

Returns true for success, false for failure.

NewRss

void NewRss(void);

Clears the RSS document.

Remove

void Remove(const wchar_t *tag);

Removes a sub-element from the RSS document.

SetAttr

void SetAttr(const wchar_t *tag, const wchar_t *attrName, const wchar_t *value);

Sets the value of a sub-element attribute.

SetDateNow

void SetDateNow(const wchar_t *tag);

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

SetDateStr

void SetDateStr(const wchar_t *tag, const wchar_t *dateTimeStr);

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

SetInt

void SetInt(const wchar_t *tag, int value);

Sets the value of an integer sub-element.

SetString

void SetString(const wchar_t *tag, const wchar_t *value);

Sets the value of a sub-element.

ToXmlString

bool ToXmlString(CkString &outStr);
const wchar_t *toXmlString(void);

Returns the RSS document as an XML string.

Returns true for success, false for failure.

Events

To implement an event callback, your application would define and implement a class that inherits from CkBaseProgressW. Your application can implement methods to override some or all of the default/empty method implementations of the CkBaseProgressW base class.

For example:

  CkRssW rss;

  MyRssProgressW callbackObj;

  rss.put_EventCallbackObject(&callbackObj);

MyRssProgressW example:

#include "CkBaseProgressW.h"

class MyRssProgressW : public CkBaseProgressW {

  public:
    MyRssProgressW();
    virtual ~MyRssProgressW();

    void AbortCheck(bool  *abort);

    void PercentDone(int pctDone, bool  *abort);

    void ProgressInfo(const wchar_t *name, const wchar_t *value);

    void TaskCompleted(CkTaskW &task);

};

AbortCheck

void AbortCheck(bool *abort);

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.

PercentDone

void PercentDone(int pctDone, bool *abort);

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.

The abort output argument provides a means for aborting the operation. Setting it to true will cause the method to abort and return a failed status (or whatever return value indicates failure).

ProgressInfo

void ProgressInfo(const wchar_t *name, const wchar_t *value);

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.

TaskCompleted

void TaskCompleted(CkTaskW &task);

Called in the background thread when an asynchronous task completes.

top