public class DOMTagger extends AbstractDocumentTagger
Extract the value of one or more elements or attributes into a target field, or delete matching elements. Applies to HTML, XHTML, or XML document.
This class constructs a DOM tree from a document or field content.
That DOM tree is loaded entirely into memory. Use this tagger with caution
if you know you'll need to parse huge files. It may be preferable to use
RegexTagger
if this is a concern. Also, to help performance
and avoid re-creating DOM tree before every DOM extraction you want to
perform, try to combine multiple extractions in a single instance
of this Tagger.
The jsoup parser library is used to load a document content into a DOM tree. Elements are referenced using a CSS or JQuery-like syntax.
Should be used as a pre-parse handler.
If a target field with the same name already exists for a document,
values will be added to the end of the existing value list.
It is possible to change this default behavior by supplying a
PropertySetter
.
By default, this filter is restricted to (applies only to) documents matching
the restrictions returned by
CommonRestrictions.domContentTypes(String)
.
You can specify your own content types if you know they represent a file
with HTML or XML-like markup tags.
When used as a pre-parse handler,
this class attempts to detect the content character
encoding unless the character encoding
was specified using setSourceCharset(String)
. Since document
parsing converts content to UTF-8, UTF-8 is always assumed when
used as a post-parse handler.
You can control what gets extracted
exactly thanks to the "extract" argument of the new method
DOMTagger.DOMExtractDetails.setExtract(String)
. Possible values are:
You can specify a fromField
as the source of the HTML to parse instead of using the document content.
If multiple values are present for that source field, DOM extraction will be
applied to each value.
You can specify a defaultValue
on each DOM extraction details. When no match occurred for a given selector,
the default value will be stored in the toField
(as opposed
to not storing anything). When matching blanks (see below) you will get
an empty string as opposed to the default value.
Empty strings and spaces are supported as default values
(the default value is now taken literally).
You can set matchBlanks
to
true
to match elements that are present
but have blank values. Blank values are empty values or values containing
white spaces only. Because white spaces are normalized by the DOM parser,
such matches will always return an empty string (spaces will be trimmed).
By default elements with blank values are not matched and are ignored.
You can specify which parser to use when reading documents. The default is "html" and will normalize the content as HTML. This is generally a desired behavior, but this can sometimes have your selector fail. If you encounter this problem, try switching to "xml" parser, which does not attempt normalization on the content. The drawback with "xml" is you may not get all HTML-specific selector options to work. If you know you are dealing with XML to begin with, specifying "xml" should be a good option.
As of 3.0.0, you can specify whether to delete any elements
matched by the selector. You can use with a "toField" or on its own.
Some options are ignored by deletions, such as
"extract" or "defaultValue". Because taggers cannot modify the document
content, deletion only applies to metadata fields. Use DOMDeleteTransformer
to modify the document content.
<handler
class="com.norconex.importer.handler.tagger.impl.DOMTagger"
fromField="(optional source field)"
parser="[html|xml]"
sourceCharset="(character encoding)">
<!-- multiple "restrictTo" tags allowed (only one needs to match) -->
<restrictTo>
<fieldMatcher
method="[basic|csv|wildcard|regex]"
ignoreCase="[false|true]"
ignoreDiacritic="[false|true]"
partial="[false|true]">
(field-matching expression)
</fieldMatcher>
<valueMatcher
method="[basic|csv|wildcard|regex]"
ignoreCase="[false|true]"
ignoreDiacritic="[false|true]"
partial="[false|true]">
(value-matching expression)
</valueMatcher>
</restrictTo>
<!-- multiple "dom" tags allowed -->
<dom
selector="(selector syntax)"
toField="(target field)"
extract="[text|html|outerHtml|ownText|data|tagName|val|className|cssSelector|attr(attributeKey)]"
matchBlanks="[false|true]"
defaultValue="(optional value to use when no match)"
delete="[false|true]"
onSet="[append|prepend|replace|optional]"/>
</handler>
<handler
class="DOMTagger">
<dom
selector="div.firstName"
toField="firstName"/>
<dom
selector="div.lastName"
toField="lastName"/>
</handler>
Given this HTML snippet...
<div class="firstName">Joe</div> <div class="lastName">Dalton</div>
... the above example will store "Joe" in a "firstName" field and "Dalton" in a "lastName" field.
DOMDeleteTransformer
Modifier and Type | Class and Description |
---|---|
static class |
DOMTagger.DOMExtractDetails
DOM Extraction Details
|
Constructor and Description |
---|
DOMTagger()
Constructor.
|
Modifier and Type | Method and Description |
---|---|
void |
addDOMExtractDetails(DOMTagger.DOMExtractDetails extractDetails)
Adds DOM extraction details.
|
boolean |
equals(Object other) |
List<DOMTagger.DOMExtractDetails> |
getDOMExtractDetailsList()
Gets a list of DOM extraction details.
|
String |
getFromField()
Gets optional source field holding the HTML content to apply DOM
extraction to.
|
String |
getParser()
Gets the parser to use when creating the DOM-tree.
|
String |
getSourceCharset()
Gets the assumed source character encoding.
|
int |
hashCode() |
protected void |
loadHandlerFromXML(XML xml)
Loads configuration settings specific to the implementing class.
|
void |
removeDOMExtractDetails(String selector)
Removes the DOM extraction details matching the given selector
|
protected void |
saveHandlerToXML(XML xml)
Saves configuration settings specific to the implementing class.
|
void |
setFromField(String fromField)
Sets optional source field holding the HTML content to apply DOM
extraction to.
|
void |
setParser(String parser)
Sets the parser to use when creating the DOM-tree.
|
void |
setSourceCharset(String sourceCharset)
Sets the assumed source character encoding.
|
void |
tagApplicableDocument(HandlerDoc doc,
InputStream document,
ParseState parseState) |
String |
toString() |
tagDocument
addRestriction, addRestriction, addRestrictions, clearRestrictions, detectCharsetIfBlank, getRestrictions, isApplicable, loadFromXML, removeRestriction, removeRestriction, saveToXML
public String getSourceCharset()
public void setSourceCharset(String sourceCharset)
sourceCharset
- character encoding of the source to be transformedpublic String getFromField()
public void setFromField(String fromField)
fromField
- from fieldpublic String getParser()
html
(default) or xml
.public void setParser(String parser)
parser
- html
or xml
.public void tagApplicableDocument(HandlerDoc doc, InputStream document, ParseState parseState) throws ImporterHandlerException
tagApplicableDocument
in class AbstractDocumentTagger
ImporterHandlerException
public void addDOMExtractDetails(DOMTagger.DOMExtractDetails extractDetails)
extractDetails
- DOM extraction detailspublic List<DOMTagger.DOMExtractDetails> getDOMExtractDetailsList()
public void removeDOMExtractDetails(String selector)
selector
- DOM selectorprotected void loadHandlerFromXML(XML xml)
AbstractImporterHandler
loadHandlerFromXML
in class AbstractImporterHandler
xml
- XML configurationprotected void saveHandlerToXML(XML xml)
AbstractImporterHandler
saveHandlerToXML
in class AbstractImporterHandler
xml
- the XMLpublic boolean equals(Object other)
equals
in class AbstractImporterHandler
public int hashCode()
hashCode
in class AbstractImporterHandler
public String toString()
toString
in class AbstractImporterHandler
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