HtmlToXml VB.NET Reference Documentation

HtmlToXml

Current Version: 10.0.0

Class for converting HTML to well-formed XML for the purpose of programmatically extracting (scraping) information from any HTML page.

Object Creation

Dim obj As New Chilkat.HtmlToXml()

Properties

DebugLogFilePath
DebugLogFilePath As String

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:

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

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DropCustomTags
DropCustomTags As Boolean

If set to true, then any non-standard HTML tags will be dropped when converting to XML.

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Html
Html As String

The HTML to be converted by the ToXml method. To convert HTML to XML, first set this property to the HTML string and then call ToXml. The ConvertFile method can do file-to-file conversions.

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LastErrorHtml
LastErrorHtml As String (ReadOnly)

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.

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LastErrorText
LastErrorText As String (ReadOnly)

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.

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LastErrorXml
LastErrorXml As String (ReadOnly)

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.

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LastMethodSuccess
LastMethodSuccess As Boolean

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.

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Nbsp
Nbsp As Integer

Determines how to handle   HTML entities. The default value, 0 will cause   entites to be convert to normal space characters (ASCII value 32). If this property is set to 1, then  's will be converted to &#160. If set to 2, then &nbps;'s are dropped. If set to 3, then &nbsp's are left unmodified.

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VerboseLogging
VerboseLogging As Boolean

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.

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Version
Version As String (ReadOnly)

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

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XmlCharset
XmlCharset As String

The charset, such as "utf-8" or "iso-8859-1" of the XML to be created. If XmlCharset is empty, the XML is created in the same character encoding as the HTML. Otherwise the HTML is converted XML and converted to this charset.

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Methods

ConvertFile
Function ConvertFile(ByVal inHtmlPath As String, ByVal destXmlPath As String) As Boolean

Converts an HTML file to a well-formed XML file that can be parsed for the purpose of programmatically extracting information.

Returns True for success, False for failure.

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DropTagType
Sub DropTagType(ByVal tagName As String)

Allows for any specified tag to be dropped from the output XML. To drop more than one tag, call this method once for each tag type to be dropped.

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DropTextFormattingTags
Sub DropTextFormattingTags()

Causes text formatting tags to be dropped from the XML output. Text formatting tags are: b, font, i, u, br, center, em, strong, big, tt, s, small, strike, sub, and sup.

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ReadFile
Function ReadFile(ByVal path As String) As Byte()

Convenience method for reading a complete file into a byte array.

Returns an empty byte array on failure

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ReadFileToString
Function ReadFileToString(ByVal filename As String, ByVal srcCharset As String) As String

Convenience method for reading a text file into a string. The character encoding of the text file is specified by srcCharset. Valid values, such as "iso-8895-1" or "utf-8" are listed at: List of Charsets.

Returns Nothing on failure

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SetHtmlBd
Function SetHtmlBd(ByVal bd As BinData) As Boolean
Introduced in version 9.5.0.77

Sets the Html property from the contents of bd.

Returns True for success, False for failure.

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SetHtmlBytes
Sub SetHtmlBytes(ByVal inData As Byte())

Sets the Html property from a byte array.

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SetHtmlFromFile
Function SetHtmlFromFile(ByVal filename As String) As Boolean

Sets the Html property by loading the HTML from a file.

Returns True for success, False for failure.

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SetHtmlSb
Function SetHtmlSb(ByVal sb As StringBuilder) As Boolean
Introduced in version 9.5.0.97

Sets the Html property from the contents of sb.

Returns True for success, False for failure.

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ToXml
Function ToXml() As String

Converts the HTML in the "Html" property to XML and returns the XML string.

Returns Nothing on failure

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ToXmlSb
Function ToXmlSb(ByVal sb As StringBuilder) As Boolean
Introduced in version 9.5.0.77

Converts the HTML in the "Html" property to XML and appends the XML to sb.

Returns True for success, False for failure.

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UndropTagType
Sub UndropTagType(ByVal tagName As String)

Causes a specified type of tag to NOT be dropped in the output XML.

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UndropTextFormattingTags
Sub UndropTextFormattingTags()

Causes text formatting tags to NOT be dropped from the XML output. Text formatting tags are: b, font, i, u, br, center, em, strong, big, tt, s, small, strike, sub, and sup.

Important: Text formatting tags are dropped by default. Call this method to prevent text formatting tags from being dropped.

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WriteFile
Function WriteFile(ByVal path As String, ByVal fileData As Byte()) As Boolean

Convenience method for saving a byte array to a file.

Returns True for success, False for failure.

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WriteStringToFile
Function WriteStringToFile(ByVal stringToWrite As String, ByVal filename As String, ByVal charset As String) As Boolean

Convenience method for saving a string to a file. The character encoding of the output text file is specified by charset (the string is converted to this charset when writing). Valid values, such as "iso-8895-1" or "utf-8" are listed at: List of Charsets.

Returns True for success, False for failure.

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