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A package that provides an API to create a DOM of HTML documents and access to its elements

Project description

=========================================================================
EasyHTML :: A package that provides an easy access to elements
of HTML and XHTML documents through the Document Object Model.
=========================================================================

Homepage: http://easyhtml.sourceforge.net/

Author: Taras Gaidukov

================================
Installation Instructions:
================================

Dependencies:

Python 3.4+

Build and install by running:

$ python setup.py build
$ sudo python setup.py install

============
Overview:
============

The package contains a module easyhtml.parser that provides a class
easyhtml.parser.DOMParser (a subclass of html.parser.HTMLParser).
This class has a method get_dom() that returns a DOM of parsed document
which is an instance of easyhtml.dom.HTMLDocument class:

from easyhtml import parser

dom_parser = parser.DOMParser()
dom_parser.feed('<html>'
' <body>'
' <h1 class='title'>Hello world!</h1>'
' <div id="content">'
' <p>First paragraph</p>'
' <p>Second paragraph</p>'
' <p>Third paragraph</p>'
' </div>'
' </body>'
'</html>')
document = dom_parser.get_dom()

The HTMLDocument class provides an API for access to all elements, their
attributes and contents. Elements of DOM are instances of one of following
classes:

HTMLDocument - a whole document
HTMLTag - a tag elements
TextNode - a text elements including HTML entities
HTMLComment - a comments in HTML code
DoctypeDeclaration - a doctype declaration of the document

Each HTML element provides two variants of its view: raw HTML code and its
"clear" text representation (as in web-browsers). A raw HTML code implemented
as raw_html property of the element:

document.raw_html # returns an HTML code of the document

And a text representation is just a str version of the element:

str(document) # returns a text representation of the document

Text representations of comments and a doctype declaration are empty since
these elements should be invisible on the page.

To access nested elements inside other ones, there are following methods:

get_tags_by_name(name) - returns all tags with specified name
get_children(query) - returns all tags that match a query*
get_element_by_id(id) - returns a tag with specified id

* query is a string that consists of conditions separated with semicolons.
A condition is pair of an attribute name and its value written through the
equality sign: "attr1=value1; attr2=value2".

First two methods return an instance of easyhtml.dom.HTMLCollection class that
contains found tags. An HTMLCollection object could be empty if there are no
tags that satisfy the conditions. The get_element_by_id() method returns a tag
with specified id since it's assumed that the id is unique and there is only
one tag with such id. If the tag is not found, None is returned.

Also, the method get_tags_by_name() is implemented as the magic method
__getattr__ that allows to get elements by their name just as an attribute:
document.div is eqivalent to document.get_tags_by_name('div')

The HTMLCollection class is a list-based collection that contains DOM elements
or other HTMLCollection objects. Like a list the collection provides an access
to its elements by their indices using get_element() method and it could be
iterated in the for-loop:

collection.get_element(0) # returns the first element of the collection
# or None if it does not exist
for element in collection:
# do something with each element

Also, the method get_element() is implemented as the magic method __getitem__
that provides a simplier syntax through the use of the square brackets
operator, so collection[0] is equivalent to collection.get_element(0)

Methods of the HTMLCollection class are similar to those of HTMLTag and
HTMLDocument:

get_tags_by_name(name) - returns all tags with specified name
get_children(query) - returns all tags that match a query
get_element_by_id(id) - returns a tag with specified id

IMPORTANT: Since the HTMLCollection is not an element of the DOM and does not
keep the hierarchy of contained elements, each element in the collection is
considered as an independent search result. And when a new search is called,
the result would be a new HTMLCollection that contains separate collections
for each element of the source HTMLCommection object. For instance, say the
document contains following code:

<div id="div1">
<p id="p1"></p>
</div>
<div id="div2">
<p id="p2"></p>
<p id="p3"></p>
</div>

then a call document.get_tags_by_name('div') returns a collection with two
tags:

Collection {
<div id="div1">
<div id="div2">
}

Then call collection.get_tags_by_name('p') returns a collection that contains
two collections with <p> tags in each one.

Collection {
Collection {
<p id="p1">
}
Collection {
<p id="p2">
<p id="p3">
}
}

Such behavior is similar to that the use of the collection in the for-loop and
making new search requests to each element separately:

collection = document.get_tags_by_name('div')
for element in collection:
sub_collection = element.get_tags_by_name('p')
# do something with found tags

The same result would be if you call a new search request to the collection
directly and use the result in the for-loop:

collection = document.get_tags_by_name('div')
collection = collection.get_tags_by_name('p')
for sub_collection in collection:
# do something with found tags

Or even shorter:

for sub_collection in document.div.p:
# do something with found tags

Please note that the get_element_by_id() method returns a single tag as well
as HTMLTag and HTMLDocument objects do, since it's assumed that the id is
unique and there is only one tag with such id in the document even if the
hierarhy of its elements has been destroyed.

In addition the HTMLCollection class provides a method that helps to refine
the request:

filter_tags_by_attrs(query) - filters found elements by specified query

Also this method is implemented as the magic method __call__, so it's possible
to filter tags using simplier syntax with brackets:

document.div(class=someclass) # returns a collection of div elements with
# the class "someclass"

Note that the filter_tags_by_attrs() method does not create a new level of
nested collections.

===========================
Package API reference:
===========================

class easyhtml.parser.DOMParser()

Creates a parser instance. The DOMParser is a subclass of
html.parser.HTMLParser class. For more details about HTMLParser usage see
the official documentation of HTMLParser at Python's website.

DOMParser Methods:

DOMParser.get_dom()

Returns an instance of HTMLDocument that is the root object of the
Document Object Model.


class easyhtml.dom.DoctypeDeclaration(decl)

A doctype declaration of the document. Used as an attribute of
easyhtml.dom.HTMLDocument objects. Is not visible in the str version of
the document, but it's present in the HTML code.

:decl: the text of the declaration, type str

DoctypeDeclaration Methods:

DoctypeDeclaration.raw_html

A property that returns a raw HTML code of the declaration. It consists of
the text passed into constructor between <! and > symbols. For instance,
<!DOCTYPE html>

DoctypeDeclaration.__str__()

Returns a str version of the declaration. It's implicitly called in the
str context. Always returns an empty string since the doctype declaration
is invisible on the page.


class easyhtml.dom.HTMLComment(text)

A comment in the HTML code. It's not visible in the str version of the
document, but it's present in the HTML code.

:text: a text of the comment, type str

HTMLComment Methods:

HTMLComment.raw_html

A property that returns a raw HTML code of the comment. It consists of the
text passed into constructor between <!-- and --> symbols. For instance,
<!-- Here is a comment -->

HTMLComment.__str__()

Returns a str version of the comment. It's implicitly called in the str
context. Always returns an empty string since comments are invisible on
the page.


class easyhtml.dom.TextNode()

A text data element in the document. It's a container for any visible
text data on the page. Could contain PlainText, NamedEntity and
NumEntity objects.

TextNode Methods:

TextNode.raw_html

A property that returns a raw HTML code of all contained objects.

TextNode.__str__()

Returns a str version of the text data. It's implicitly called in the str
context. Includes corresponding characters instead of contained HTML
entities.

TextNode.append(element)

Adds an element to the end of the list.

:element: an element to append, type easyhtml.dom.HTMLText (a superclass
of PlainText, NamedEntity and NumEntity classes.


class easyhtml.dom.PlainText(text)

A plain text on the page (without HTML entities). It's used inside of the
TextNode element only.

:text: a text of the element, type str

PlainText Methods:

PlainText.raw_html

A property that returns all characters of the text as it is in the HTML
document.

PlainText.__str__()

Returns a str version of the text. It's implicitly called in the str
context. Replaces sequences of white space characters with single spaces.


class easyhtml.dom.NamedEntity(name)

A named HTML entity. It's used inside of the TextNode element only. If the
entity with specified name does not exist, the KeyError would be rised.

:name: a name of the entity, type str

NamedEntity Methods:

NamedEntity.raw_html

A property that returns an HTML code of the entity. It consists of the
name passed into constructor between & and ; symbols.

NamedEntity.__str__()

Returns a str version of the entity. It's implicitly called in the str
context. For instance, it returns the "<" character for the entity with
the code &lt;


class easyhtml.dom.NumEntity(num)

A numeric HTML entity specified by decimal or hexadecimal code. It's used
inside of the TextNode element only. If the entity with specified numeric
code does not exist, the KeyError would be rised.

:num: a numeric code of the entity, type str

NamedEntity Methods:

NamedEntity.raw_html

A property that returns an HTML code of the entity. It consists of the
name passed into constructor between &# and ; symbols.

NamedEntity.__str__()

Returns a str version of the entity. It's implicitly called in the str
context. For instance, it returns the "<" character for the entity with
the code &#60; or &#x3c;


class HTMLTag(name, attrs)

An HTML tag. Could be single such as <br> or complex such as <p>...</p>.
Complex tags could contain other elements (TextNode, HTMLComment or
HTMLTag).

:name: a name of the tag, type str
:attrs: a list of tuples with attributes of the tag,
format [(attr1, value1), (attr2: value2)]

HTMLTag Methods:

HTMLTag.single

Aproperty that indicates whether the tag is single, i.e. does not require
an endtag. The result depends on the name of the tag: there is a list of
the single tags and if the name matches any item from the list, the tag is
considered as single.

HTMLTag.raw_html

A property that returns an HTML code of the tag. It consists of the
start tag, inner HTML code and the end tag.

HTMLTag.__str__()

Returns a str version of the tag. It's implicitly called in the str
context. It consists of the str versions of all contained elements.
For instance, it returns "Hello, world!" for the tag
<p>Hello, world!</p>

HTMLTag.start_tag

A property that returns an HTML code of the start tag. It consists of the
name and attributes of the tag in the angle brackets:
<name attr1="value1" attr2="value2">

HTMLTag.end_tag

A property that returns an HTML code the end tag. It consists of the name
with the slash on the front in the angle brackets: </name>

HTMLTag.inner_html

A property that returns HTML codes of all contained elements.

HTMLTag.get_attributes()

Returns a dictionary of attributes.

HTMLTag.get_attr(name):

Returns a value of the attribute with specified name of None if such
attribute does not exist.

:name: a name of the attribute, type str

HTMLTag.check_attr(name, value)

Returns True if the value of the attribute with specified name matches
the specified value. Otherwise returns False.

Note that the "class" attribute in the HTML could be defined as a list of
several CSS classes separated by the white space characters. The method
returns True if specified value of the "class" attribute matches one of
those classes in theHTML. For instance, if the tag is defined as
<div class="foo bar">, then check_attr("class", "foo") returns True and
check_attr("class", "bar") returns True as well.

:name: a name of the attribute, tupe str
:value: a value of the atribute, type str

HTMLTag.check_attrs(query)

Returns True if all attributes of the tag and its values match specified
query. Otherwise returns False. The query is a string of pairs attr=value
separated by semicolons and any number of spaces. For instance,
"attr1=value1; attr2=value2"

:query: a query string, type str

HTMLTag.append(element)

Adds an element to the end of the list.

:element: an element to append, allowed types:
easyhtml.dom.HTMLTextNode
easyhtml.dom.HTMLTag
easyhtml.dom.HTMLComment

HTMLTags.tags

A property that returns a generator object that generates all contained
tags of the tag.

HTMLTag.get_all_tags()

Returns a generator object that generates all contained tags of the tag
including all their nested tags recursively.

HTMLTag.get_tags_by_name(name)

Returns an easyhtml.dom.HTMLCollection object contains tags with specified
name including nested tags. The same functionality is provided by getting
the tag's name as an attribute: tag.get_tags_by_name("name") = tag.name

:name: a name of search tags, type str

HTMLTag.get_children(query)

Returns an easyhtml.dom.HTMLCollection object that contains tags with
specified in the query attributes. The query is a string of pairs
attr=value separated by semicolons and any number of spaces. For instance,
"attr1=value1; attr2=value2"

:query: a query string, type str

HTMLTag.get_element_by_id(e_id)

Returns a tag with specified id. If such tag does not exist returns None.

:e_id: an ID of the tag, type str

HTMLTag.filter_tags_by_attrs(query)

Returns the tag itself if it matches the query, otherwise returns None.
The query is a string of pairs attr=value separated by semicolons and any
number of spaces. For instance, "attr1=value1; attr2=value2"

:query: a query string, type str


class easyhtml.dom.HTMLDocument()

A root document object. Contains all HTML elements and provides an API to
access them.

HTMLDocument Methods:

HTMLDocument.raw_html

A property that returns an HTML code of the document.

HTMLDocument.__str__()

Returns a str version of the document. It's implicitly called in the str
context. It consists of the str versions of all contained elements.

HTMLDocument.doctype

A property that contains the DoctypeDeclaration object of the document.
The property allows to write a new doctype to it.

HTMLDocument.inner_html

A property that returns HTML codes of all contained elements.

HTMLDocument.append(element)

Adds an element to the end of the list.

:element: an element to append, allowed types:
easyhtml.dom.HTMLTextNode
easyhtml.dom.HTMLTag
easyhtml.dom.HTMLComment

HTMLDocument.tags

A property that returns a generator object that generates all contained
tags of the document.

HTMLDocument.get_all_tags()

Returns a generator object that generates all contained tags of the
document including all their nested tags recursively.

HTMLDocument.get_tags_by_name(name)

Returns an easyhtml.dom.HTMLCollection object contains tags with specified
name including nested tags. The same functionality is provided by getting
the tag's name as an attribute: doc.get_tags_by_name("name") = doc.name

:name: a name of search tags, type str

HTMLDocument.get_children(query)

Returns an easyhtml.dom.HTMLCollection object that contains tags with
specified in the query attributes. The query is a string of pairs
attr=value separated by semicolons and any number of spaces. For instance,
"attr1=value1; attr2=value2"

:query: a query string, type str

HTMLDocument.get_element_by_id(e_id)

Returns a tag with specified id. If such tag does not exist returns None.

:e_id: an ID of the tag, type str


class easyhtml.dom.HTMLCollection(items)

A result object returned by get_* methods. Collection is an object that
contains found tags or collections of tags.

:items: an iterable object contains a content of the collection

The collection object is iterable and provides the __getitem__ method to
access its items using [] operator. Also it provides the __len__ method
so len(collection) would return actual count of elements in the
collection.

HTMLCollection Methods:

HTMLCollection.get_element(index)

Returns an element with specified index. If such element does not exist
None would be returned. The same functionality is provided by [] operator.

:index: an index of the element, type int

HTMLCollection.get_tags_by_name(name)

Returns an easyhtml.dom.HTMLCollection object contains collections with
the results of such search request to each contained element. The same
functionality is provided by getting the tag's name as an attribute:
collection.get_tags_by_name("name") = collection.name

:name: a name of search tags, type str

HTMLCollection.get_children(query)

Returns an easyhtml.dom.HTMLCollection object that contains collections
with the results of such search request to each contained element. The
query is a string of pairs attr=value separated by semicolons and any
number of spaces. For instance, "attr1=value1; attr2=value2"

:query: a query string, type str

HTMLCollection.filter_tags_by_attrs(query)

Filters contained tags or tags in contained collections leaving those
match specified query. If there is no such tags the collection would be
empty. The query is a string of pairs attr=value separated by semicolons
and any number of spaces. For instance, "attr1=value1; attr2=value2"

The same functionality is provided by the __call__ method, so
collection.filter_tags_by_attrs("attr=value") = collection("attr=value")

Note that since the return value of search methods are the HTMLCollection
object, you could use just document.div("class=foo") instead of
document.div.filter_tags_by_attrs("class=foo")

:query: a query string, type str

HTMLCollection.get_element_by_id(e_id)

Returns a tag with specified id. If such tag does not exist returns None.

:e_id: an ID of the tag, type str

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