New to Wicket and have read all the tutorials and looked at all the
sample code and searched on list serve discussion for the topic.
Has any thought or code been put in place to allow the use of XPATH and
a DOM tree as a DataModel. If the Presentation layer of the data follows
the XML layout then it would reduce the need to write a java class to
model the data and associate the view.
If you had a read only phone book application where you have the normal
data elements that go with a phone book
<PhoneBookEntry>
<LastName>Smith</LastName>
<FirstName>John</FirstName>
<PhoneNumber>12345678</PhoneNumber>
<PhoneBookEntry>
<PhoneBookEntry>
<LastName>Williams</LastName>
<FirstName>John</FirstName>
<PhoneNumber>15551212</PhoneNumber>
<PhoneBookEntry>
Steps for phone book application:
1. You would load the XML data into a DOM object using say JDOM.
2. Create a custom search page to hide the XPATH syntax but would prompt
for values from the user. Could be automated but hand coding would not
be a problem. The user is looking for Last Name: Smith so the XPATH
would be
List result =
parentElement.selectNodes(/PhoneBookEntry[LastName='Smith'])
This would return a list of Elements that match the search. In this case
it would be one entry but if the search was
List result =
parentElement.selectNodes(/PhoneBookEntry[FirstName='John'])
would return two results. The user would see a results page and would
then click on the link of interest. The results page would also be
driven by XPATH for displaying summarized results of key child elements
based on the needs of the application. When the user clicks on the link
the parentElement for that result is passed to a panel to view the data.
The data model for the panel would be driven by XPATH and the
parentElement to associate the data with the view. In defining the panel
you would want to do something like this.
add(new Label("First Name", new XPATHModel(parentElement, "[FirstName]"));
add(new Label("Last Name", new XPATHModel(parentElement, "[LastName"]));
add(new Label("Phone Number", new XPATHModel(parentElement, "[PhoneNumber"]));
This would be all that is required to show the results on the page. You
also get the power of XPATH as your search expression. You could also
provide an option to pass a defined instance of java.util.Formatter to
handle the presentation of the data. It appears that future versions of
XPATH may include indexing and compilation of the XPATH search
expression so long term performance for huge data sets would not be a
problem. When the data is properly organized XPATH is very fast. For
example I would not put 1 million phone book entries as the children of
one node. But would take the rational index of say last name and make
that a child node of the parent with entries that share the same last
name as children of that node.
The same approach would also work for updating the data but would
require additional support code but it should be less if you had to
write a custom model.
My challenge is the learning curve on wicket and hard deadlines I am
working on as part of research for my PhD dissertation. If someone on
the list could get me to a good starting point(example code that follows
the same concept) with thoughts and/or observations on why this would or
would not work I would appreciate it.
I have the need to display a large amount of genetic data that is
organized via XML and trying to avoid writing a custom data model for
each object entity. Would much rather describe the model with XPATH.
Thanks
Scooter
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