Table of Contents generated with DocToc
- Python htmltree project
- Easy to learn. Consistent, simple syntax.
- 85 predefined tag functions.
- Create HTML on the fly or save as static files.
- Flexible usage and easy extension.
- Run locally with CPython or as Javascript in the browser using Jacques De Hooge's Transcrypt™ Python to JS transpiler
- Dependencies: Python 3.x
pip install htmltree
from htmltree import *
head = Head()
body = Body()
doc = Html(head, body)
>>> print(doc.render(0))
<html>
<head>
</head>
<body>
</body>
</html>
who = Meta(name="author",content="Your Name Here")
head.C.append(who)
body.A.update(dict(style={'background-color':'black'}))
banner = H1("Hello, htmltree!", _class='banner', style={'color':'green'})
body.C.append(banner)
>>> print(doc.render(0))
<html>
<head>
<meta content="Your Name Here" name="author">
</head>
<body style="background-color:black;">
<h1 class="banner" style="color:green;">
Hello, htmltree!
</h1>
</body>
</html>
In the examples above, we created elements and assigned them to variables so we could alter their content later. However, we could also have written it out all at once.
doc = Html(
Head(
Meta(name="author",content="Your Name Here")),
Body(
H1("Hello, htmltree!", _class='banner', style={'color':'green'}),
style={'background-color':'black'}))
That's short and clean and renders exactly the same html. It also mimics the page structure but sacrifices ease of alteration later in the execution. Your choices should come down to whether you're creating static html or dynamic content based on information that's not available until run time.
Did you notice the underscore in H1("Hello, htmltree!", _class='banner', ...)? It's written that way because class is a Python keyword. Trying to use it as an identifier will raise a syntax error.
As a convenience, all the wrapper functions strip off leading and trailing underscores in attribute names, so class_ would also work. Normal HTML doesn't use underscores in attribute names so this fix is safe to use. I think for as a <label> attribute is the only other conflict in standard HTML.
The wrapper functions also replace internal underscores in attribute names with dashes. That avoids the problem of Python trying to interpret data-role="magic" as a subtraction expression. Use data_role="magic" instead. If you need to style with vendor-specific attributes that begin with a '-', add a trailing underscore, e.g. _moz_style_ is converted to -moz-style.
The conversion happens when the element is created, not when it is rendered. If you add, update or replace an element attribute after it is created, use the attribute's true name, e.g. mybutton.A.update({'class': 'super-button'}) rather than mybutton.A.update(dict(_class='super-button')).
Use htmltree's renderToFile method and Python's standard webbrowser module.
import webbrowser
fileurl = doc.renderToFile('path/to/somefile.html')
webbrowser.open(fileurl)
The Quick Start example should look like this:
Importing * from htmltree.py provides 85 wrapper functions (as of this writing) that cover the most of the common non-obsolete HTML5 tags. To see the most up-to-date list you can do help(htmltree) from the command line of a Python interactive session or look futher down on this page for a listing. The function names and arguments follow simple and consistent conventions that make use of Python's *args, **kwargsfeatures.
- Functions are named by tag with initial caps, e.g.
Html() - The signature for non-empty tags is
Tagname(*content, **attrs) - The signature for empty tags is
Tagname(**attrs)(Empty refers to elements that enclose no content and need no closing tag -- like<meta>,<br>, etc.)
To create, say, a div with two empty paragraphs separated by a horizontal rule element, you'd write
mydiv = Div(P(), Hr(), P(), id=42, name='puddintane')
Because the first three args are unnamed Python knows they belong, in order, to *content. The last two arguments are named and therefore belong to **attrs, the attributes of the div.
Python's rules about not mixing list and keyword arguments apply. In every element, put all the *content args first, followed by all the **attrs arguments.
The <style> tag is the only exception to the pattern. Its signature is Style(**content). This is done to reduce (but alas not completely eliminate) the need for quoting the selectors in CSS rulesets.
- If you need to set attributes on a style element, do it in a secondary call as shown in the doctest below.
style = Style(body=dict(margin='4px'), p=dict(color='blue'))
style.A.update({'type':'text/css'})
style.render()
'<style type="text/css">body { margin:4px; } p { color:blue; }</style>'
- See Writing CSS later in this document for more dicussion of
Style().
The design pattern for htmltree is "as simple as possible but not simpler." Using built-in Python objects, dicts and lists, means that all the familiar methods of those objects are available when manipulating trees of Elements. Notice, for instance, the use of update and append in the Quick start examples.
body.A.update(dict(style={'background-color':'black'}))
body.C.append(H1("Hello, htmltree!", _class='myclass', id='myid'))
But wait a minute! What are body.A and body.C? Read on ...
You can access and modify the attributes and content of an element el as el.A and el.C respectively. The tagname is also available as el.T though this is generally not so useful as the other two.
The attribute member, el.A is an ordinary Python dictionary containing whatever keyword arguments were passed when the element was created. You can modify it with update() as shown in the Quick Start example or use any of the other dictionary methods on it. You can also replace it entirely with any dict-like object that has an items() method that behaves like dict.items()
The content member, el.C is normally a Python list. It contains all the stuff that gets rendered between the closing and ending tags of an element. The list may hold an arbitrary mix of strings, ints, float, and objects. In normal usage, the objects are of type htmltree.Element. This is the element type returned by all the functions in htmltree.py. You can use all the normal Python list methods (append, insert, etc) to manipulate the list.
(If you insert objects (other than those listed above), they should have a render(indent=-1) method that returns valid HTML with the same indentation conventions as the htmltree.Element.render method described in the next section.)
The render method emits HTML. In the examples above, we've called it as doc.render(0) to display the entire document tree in indented form. Calling it with no arguments emits the HTML as a single line with no breaks or spaces. Values > 0 increase the indentations by 2 spaces * the value.
>>> print(head.render())
<head><meta name="author" content="Your Name Here"/></head>
>>> print(head.render(0))
<head>
<meta name="author" content="Your Name Here"/>
</head>
>>> print(head.render(1))
<head>
<meta name="author" content="Your Name Here"/>
</head>
To include the <!DOCTYPE html> declaration and the beginning of the document, you can use the flag, doctype_declaration.
>>> print(doc.render(doctype_declaration=True))
<!DOCTYPE html><html><head></head><body></body></html>
>>> print(doc.render(0, doctype_declaration=True))
<!DOCTYPE html>
<html>
<head>
</head>
<body>
</body>
</html>
>>> print(doc.render(1, doctype_declaration=True))
<!DOCTYPE html>
<html>
<head>
</head>
<body>
</body>
</html>
The renderToFile() method also accepts the indent and doctype_declaration arguments.
The simplest possible extension is wrapping a frequently used tag to save a little typing. This is already done for you for all the wrapper functions in htmltree.py. But if you need something that's not defined it only takes two lines of code (not counting the import).
from htmltree import KWElement
def Foo(*content, **attrs):
return KWElement('foo', *content, **wrappers)
For an empty tag element, omit the content arg and pass None to KWElement().
def Bar(**attrs):
return KWElement('bar', None, **attrs)
Wrapping commonly used fragments in a function is easy and useful, e.g.
def docheadbody():
head = Head()
body = Body()
doc = Html(head, body)
return doc, head, body
>>> doc, head, body = docheadbody()
Use loops to simplify the creation of many similar elements.
for id in ('one', 'two', 'three'):
content = "Help! I'm trapped in div {}.".format(id)
body.C.append(Div(content, id=id))
>>> print(body.render(0))
<body>
<div id="one">
Help! I'm trapped in div one.
</div>
<div id="two">
Help! I'm trapped in div two.
</div>
<div id="three">
Help! I'm trapped in div three.
</div>
</body>
Using htmltree with Transcrypt
This project was designed from the ground up to be compatible with Transcrypt to create a pure Python development environment for HTML/CSS/JS on both sides of the client/server divide.
If you've installed htmltree with pip, Transcrypt will find it when transpiling your Python files to JavaScript if you import it as htmltree. If you have a need to install and access htmltree by other means, see
- http://www.transcrypt.org/docs/html/special_facilities.html for information about Transcrypt's module mechanism and
- #3 for a discussion of some specific ways to locate htmltree at compile time.
Also, look at the modules sanitycheck.py and client.py in the tests/ directory as a template for developing and testing with htmltree and Transcrypt. For a more elaborate template with a built-in server, AJAX/JSON data updates and automatic rebuild/reload when source files change, see NearlyPurePythonWebAppDemo
All the functions should work the same as under CPython. If not, please submit an issue on GitHub so I can fix it!
Use the Style() element to create CSS rulesets for your HTML, for example
>>> mystyle = Style(h2=dict(margin_top='4px', color='red'))
>>> doc = Html(Head(mystyle), Body(H2("Hello!")))
>>> print(doc.render(0))
<html>
<head>
<style>
h2 { color:red; margin-top:4px; }
</style>
</head>
<body>
<h2>
Hello!
</h2>
</body>
</html>
In python, {} and dict() both define dictionaries. The difference is that dict treats keyword arguments as strings, so
>>> {'foo':1, 'bar':2} == dict(foo=1, bar=2)
True
Using dict() with keyword arguments saves having to quote keywords and htmltree tries to help by converting underscores in keywords to hyphens (as discussed earlier in this document). On the other hand, the CSS selector syntax permits strings that are not valid Python keywords, so the best practice for non-trivial rulesets is to create a dictionary of dictionaries, as shown below, and supply that as the argument to Style(). Don't forget the two asterisks in front!
mycss = {
'a.someclass' : {'color':'red', 'margin-top':'0.5em !important'},
'div p #id:first-line' : {'background-style': 'none'}
}
mystyle = Style(**mycss) ## Don't forget the two asterisks in front
>>> print(mystyle.render(0))
<style>
div p #id:first-line { background-style:none; }
a.someclass { color:red; margin-top:0.5em !important; }
</style>
If you compare the dictionary definition of mycss with the rendered css
output, you'll see that the differences are as follows:
- Quote every item,
- A colon between each selector and its property/value pairs,
- A comma after each rule definition,
- Separate property:value pairs with commas instead of semicolons.
When two CSS selectors apply with equal specificity to the same property of an element, the last one wins. You should not rely on the Style() object to render rules in any particular order because Python dictionaries are, by definition, unordered collections.
Html(*content, **attrs):
Head(*content, **attrs):
Body(*content, **attrs):
Link(**attrs):
Meta(**attrs):
Title(*content, **attrs):
Style(**content):
Address(*content, **attrs):
Article(*content, **attrs):
Aside(*content, **attrs):
Footer(*content, **attrs):
Header(*content, **attrs):
H1(*content, **attrs):
H2(*content, **attrs):
H3(*content, **attrs):
H4(*content, **attrs):
H5(*content, **attrs):
H6(*content, **attrs):
Nav(*content, **attrs):
Section(*content, **attrs):
Blockquote(*content, **attrs):
Dd(*content, **attrs):
Div(*content, **attrs):
Dl(*content, **attrs):
Dt(*content, **attrs):
Figcaption(*content, **attrs):
Figure(*content, **attrs):
Hr(**attrs):
Li(*content, **attrs):
Main(*content, **attrs):
Ol(*content, **attrs):
P(*content, **attrs):
Pre(*content, **attrs):
Ul(*content, **attrs):
A(*content, **attrs):
B(*content, **attrs):
Br(**attrs):
Cite(*content, **attrs):
Code(*content, **attrs):
Em(*content, **attrs):
I(*content, **attrs):
S(*content, **attrs):
Samp(*content, **attrs):
Small(*content, **attrs):
Span(*content, **attrs):
Strong(*content, **attrs):
Sub(*content, **attrs):
Sup(*content, **attrs):
U(*content, **attrs):
Area(**attrs):
Audio(*content, **attrs):
Img(**attrs):
Map(*content, **attrs):
Track(**attrs):
Video(*content, **attrs):
Embed(**attrs):
Object(*content, **attrs):
Param(**attrs):
Source(**attrs):
Canvas(*content, **attrs):
Noscript(*content, **attrs):
Script(*content, **attrs):
Caption(*content, **attrs):
Col(**attrs):
Table(*content, **attrs):
Tbody(*content, **attrs):
Td(*content, **attrs):
Tfoot(*content, **attrs):
Th(*content, **attrs):
Thead(*content, **attrs):
Tr(*content, **attrs):
Button(*content, **attrs):
Datalist(*content, **attrs):
Fieldset(*content, **attrs):
Form(*content, **attrs):
Input(**attrs):
Label(*content, **attrs):
Legend(*content, **attrs):
Meter(*content, **attrs):
Optgroup(*content, **attrs):
Option(*content, **attrs):
Output(*content, **attrs):
Progress(*content, **attrs):
Select(*content, **attrs):
Textarea(*content, **attrs):