My PagedTableBean constructor looks like the following:
public PagedTableBean(Connection conn,
String sql,
long pageNumber,
long pageSize)
throws PagedTableException
{
this.pageNumber = pageNumber;
this.pageSize = pageSize;
this.conn = conn;
this.sql = sql;
populateBean();
}
private void populateBean()
throws PagedTableException
{
long startRow = (((pageNumber-1)*pageSize)+1);
long endRow = (pageNumber*pageSize);
String q = "SELECT * FROM (SELECT ROWNUM ROWNO, Q.* "
+ "FROM (" + sql + ") Q WHERE ROWNUM <= "
+ endRow + ") WHERE ROWNO >= " + startRow;
try {
PreparedStatement ps = conn.prepareStatement(q);
ResultSet rs = ps.executeQuery();
rows = new RowSetDynaClass(rs,true);
rs.close();
ps.close();
}
catch(SQLException e) {
throw new PagedTableException(e.getMessage());
}
}
public Collection getRows() {
return((Collection)rows.getRows());
}
It was that simple :-) And now anytime I need paging done, I simply store
in my form the page number and size and pass those into my action which
instantiates this request bean each time, executes the query and returns the
subset of data in the request scope to the forwarded JSP. Since the action
my form posts to drives what the return data would be since that is where we
keep our "business logic", this will work well and apply anywhere we need
this technique.
I also got fancy and added a few helper methods to this PagedTableBean class
to give me quick access to the current page number, whether a prev/next page
exists, as well as a method called getSize() that issues a "SELECT COUNT(1)
FROM (" + sql + ")" call to the database to get the number of total records.
This way, I can easily show something like:
[<<] 100-150 of 7532 records [>>]
Let me know if you have any questions!
Chris
-----Original Message-----
From: Rajat Pandit, Gurgaon [mailto:[EMAIL PROTECTED]
Sent: Tuesday, June 15, 2004 1:54 AM
To: 'Struts Users Mailing List'
Subject: RE: RowSetDynaClass
Hey Chris,
This seems like a pretty neat solution you have out here, could please
explain this, as pagination stuff is kind of the most complicated things
that I have to deal with and I see my self coding the same thing again and
again over a period of time. I would really appreciate your time and effort.
Thanks in adv. rajat
-----Original Message-----
From: CRANFORD, CHRIS [mailto:[EMAIL PROTECTED]
Sent: Tuesday, June 15, 2004 11:17 AM
To: 'Struts Users Mailing List'
Subject: RE: RowSetDynaClass
Found the answer ;-) ... Avoid the <c:...> tags all together and stick with
the standard struts tags. The following worked:
<logic:iterate id="row" name="results" property="rows" scope="request"
indexId="rowid">
<bean:write name="row" property="item_id" /> - <bean:write name="row"
property="item_product_number"/> </logic:iterate>
Now have a fast, efficient paging mechanism that permits me to pass in a
database connection object, the sql query to execute, starting page # and
size and it handles the rest by populating itself from the database, closing
the resultset when finished and leaves the presentation part up to my JSP as
above!
Gotta love struts!
Chris
-----Original Message-----
From: CRANFORD, CHRIS [mailto:[EMAIL PROTECTED]
Sent: Tuesday, June 15, 2004 12:35 AM
To: '[EMAIL PROTECTED]'
Subject: RowSetDynaClass
I am storing a RowSetDynaClass property in my java class and I have
implemented a method on my class as follows:
public Collection getRows() {
return((Collection)rsdc.getRows());
}
In my action, I store my custom class object reference as follows:
request.setAttribute("results", myResultsObj);
Then in my jsp, I do the following:
<bean:define scope="request" id="data" name="results" property="rows" />
<c:forEach var="row" items="${data}" varStatus="rowid">
<c:out value="${rowid.count}"/>. <c:out value="${row.item_id}" /> -
<c:out value="${row.item_product_number}" />
</c:forEach>
I get the following error:
[ServletException in:/pages/test-body.jsp]
An error occurred while evaluating custom action attribute "value" with
value "${row.item_id}": Unable to find a value for "item_id" in object of
class "org.apache.commons.beanutils.BasicDynaBean" using operator "." (null)
Can someone tell me what I am doing wrong here and how I can do this
properly to get it to work?
_______________________________________________________
Chris Cranford
Programmer/Developer
SETECH Inc. & Companies
6302 Fairview Rd, Suite 201
Charlotte, NC 28210
Phone: (704) 362-9423, Fax: (704) 362-9409, Mobile: (704) 650-1042
Email: [EMAIL PROTECTED]
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