Post-rendering Resource Inclusion
Project description
The resource library is a Zope 3 extension that is designed to make the inclusion of JavaScript, CSS, and other resources easy, cache-friendly, and component-friendly.
Detailed Dcoumentation
Resource Library
The resource library is designed to make the inclusion of JavaScript, CSS, and other resources easy, cache-friendly, and component-friendly. For instance, if two widgets on a page need the same JavaScript library, the library should be only loaded once, but the widget designers should not have to concern themselves with the presence of other widgets.
Imagine that one widget has a copy of a fictional Javascript library. To configure that library as available use ZCML like this:
>>> zcml("""
... <configure
... xmlns="http://namespaces.zope.org/zope"
... package="zc.resourcelibrary">
...
... <resourceLibrary name="some-library">
... <directory source="tests/example"/>
... </resourceLibrary>
...
... </configure>
... """)
This is exactly equivalent to a resourceDirectory tag, with no additional effect.
Loading Files
It is also possible to indicate that one or more Javascript or CSS files should be included (by reference) into the HTML of a page that needs the library. This is the current difference between resourceLibrary and resourceDirectory.
>>> zcml("""
... <configure
... xmlns="http://namespaces.zope.org/zope"
... package="zc.resourcelibrary">
...
... <resourceLibrary name="my-lib">
... <directory
... source="tests/example/my-lib"
... include="included.js included.css"
... />
... </resourceLibrary>
...
... </configure>
... """)
If a file is included that the resource library doesn’t understand (i.e. it isn’t Javascript or CSS), an exception will occur.
>>> zcml("""
... <configure
... xmlns="http://namespaces.zope.org/zope"
... package="zc.resourcelibrary">
...
... <resourceLibrary name="bad-lib">
... <directory
... source="tests/example/my-lib"
... include="included.bad"
... />
... </resourceLibrary>
...
... </configure>
... """)
Traceback (most recent call last):
...
ZopeXMLConfigurationError:...
ConfigurationError: Resource library doesn't know how to include this
file: "included.bad".
Usage
Components signal their need for a particular resource library (Javascript or otherwise) by using a special TAL expression. (The use of replace is not mandated, the result may be assigned to a dummy variable, or otherwise ignored.)
>>> zpt('<tal:block replace="resource_library:my-lib"/>')
We’ll be using a testbrowser.Browser to simulate a user viewing web pages.
>>> from zope.testbrowser.testing import Browser
>>> browser = Browser()
>>> browser.addHeader('Authorization', 'Basic mgr:mgrpw')
When a page is requested that does not need any resource libraries, the HTML will be untouched.
>>> browser.open('http://localhost/zc.resourcelibrary.test_template_1')
>>> browser.contents
'...<head></head>...'
When a page is requested that uses a component that needs a resource library, the library will be referenced in the rendered page.
>>> browser.open('http://localhost/zc.resourcelibrary.test_template_2')
A reference to the JavaScript is inserted into the HTML.
>>> '/@@/my-lib/included.js' in browser.contents True
And the JavaScript is available from the URL referenced.
>>> browser.open('/@@/my-lib/included.js')
>>> print browser.contents
function be_annoying() {
alert('Hi there!');
}
For inclusion of resources the full base url with namespaces is used.
>>> browser.open('http://localhost/++skin++Basic/zc.resourcelibrary.test_template_2')
>>> print browser.contents
<html...
src="http://localhost/++skin++Basic/@@/my-lib/included.js"...
</html>
A reference to the CSS is also inserted into the HTML.
>>> browser.open('http://localhost/zc.resourcelibrary.test_template_2')
>>> '/@@/my-lib/included.css' in browser.contents
True
And the CSS is available from the URL referenced.
>>> browser.open('/@@/my-lib/included.css')
>>> print browser.contents
div .border {
border: 1px silid black;
}
A reference to an unknown library causes an exception.
>>> browser.open('http://localhost/zc.resourcelibrary.test_template_3')
Traceback (most recent call last):
...
RuntimeError: Unknown resource library: "does-not-exist"
Library usage may also be signaled programattically. For example, if a page would not otherwise include a resource library…
>>> page = ('<html><head></head>' ... '<body tal:define="unused view/doSomething">' ... 'This is the body.</body>')>>> class View(object): ... def doSomething(self): ... pass>>> zpt(page, view=View()) '...<head></head>...'
…but we programmatically indicate that a resource library is needed, it will be included.
>>> import zc.resourcelibrary >>> class View(object): ... def doSomething(self): ... zc.resourcelibrary.need('my-lib')>>> '/@@/my-lib/included.js' in zpt(page, view=View()) True
Dependencies
If a resource library registers a dependency on another library, the dependency must be satisfied or an error will be generated.
>>> zcml("""
... <configure
... xmlns="http://namespaces.zope.org/zope"
... package="zc.resourcelibrary">
...
... <resourceLibrary name="dependent-but-unsatisfied" require="not-here">
... <directory source="tests/example"/>
... </resourceLibrary>
...
... </configure>
... """)
Traceback (most recent call last):
...
ConfigurationExecutionError:...Resource library "dependent-but-unsatisfied"
has unsatisfied dependency on "not-here"...
When the dependencies are satisfied, the registrations will succeed.
>>> zcml("""
... <configure
... xmlns="http://namespaces.zope.org/zope"
... package="zc.resourcelibrary">
...
... <resourceLibrary name="dependent" require="dependency">
... <directory source="tests/example" include="1.js"/>
... </resourceLibrary>
...
... <resourceLibrary name="dependency">
... <directory source="tests/example" include="2.css"/>
... </resourceLibrary>
...
... </configure>
... """)
If one library depends on another and the first library is referenced on a page, the second library will also be included in the rendered HTML.
>>> zpt('<tal:block replace="resource_library:dependent"/>')
>>> browser.open('http://localhost/zc.resourcelibrary.test_template_4')
>>> '/@@/dependent/1.js' in browser.contents
True
>>> '/@@/dependency/2.css' in browser.contents
True
Order matters, espacially for js files, so the dependency should appear before the dependent library in the page
>>> print browser.contents.strip() <html>...dependency/2.css...dependent/1.js...</html>
Error Conditions
Errors are reported if you do something wrong.
>>> zcml("""
... <configure
... xmlns="http://namespaces.zope.org/zope"
... package="zc.resourcelibrary">
...
... <resourceLibrary name="some-library">
... <directory source="does-not-exist"/>
... </resourceLibrary>
...
... </configure>
... """)
Traceback (most recent call last):
...
ZopeXMLConfigurationError: ...
ConfigurationError: Directory u'...does-not-exist' does not exist
Multiple Heads
On occasion the body of an HTML document may contain the text “<head>”. In those cases, only the actual head tag should be manipulated. The first occurrence of “<head>” has the script tag inserted…
>>> browser.open('http://localhost/zc.resourcelibrary.test_template_5')
>>> print browser.contents
<html>...<head> <script src="http://localhost/@@/my-lib/included.js"...
…but that is the only time it is inserted.
>>> browser.contents.count('src="http://localhost/@@/my-lib/included.js"')
1
Future Work
We want to be able to specify a single file to add to the resource.
We may want to be able to override a file in the resource with a different file.
Currently only one <directory> tag is allowed per-library. If multiple tags are allowed, should they be merged or have distinct prefixes?
Add a test to ensure that files are only included once, and in the proper order
CHANGES
0.6.1 (2007-11-03)
Update package meta-data.
Fixed package dependencies.
Merged functional and unit tests.
0.6.0 (2006-09-22)
???
0.5.2 (2006-06-15)
Add more package meta-data.
0.5.1 (2006-06-06)
Update package code to work with newer versions of other packages.
0.5.0 (2006-04-24)
Initial release.
Release history Release notifications | RSS feed
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