Serializing database query results for use as dataproviders

I am executing my database queries in Java and passing my results to flex and creating a chart or datagrid based on the results. The problem is, I don't know how to code this in Java in a way that flex would understand it. For instance, Flex wants:
<mx:DataGrid id="dg" dataProvider="{myArray}">
<mx:columns>
         <mx:DataGridColumn dataField="column1" />
         <mx:DataGridColumn dataField="column2" />
          
         <mx:DataGridColumn dataField="columnN" />
      </mx:columns>
</mx:DataGrid>
I need to create this table-like array in Java and have it readable as a dataprovider by flex. I know about ArrayCollections and Java ArrayLists can be nicely converted to this in Flex, but I just don't know how to create them with a column1, column2, etc. when I don't know from query to query how many columns will be in my results.
Any help would be greatly appreciated!

You don't know in advanced the columns that your queries will return?
Or the number of records?
Sincerely,
Michael
El 30/04/2009, a las 13:47, Cr99 <[email protected]> escribió:
>
I am executing my database queries in Java and passing my results to
flex and creating a chart or datagrid based on the results. The
problem is, I don't know how to code this in Java in a way that flex
would understand it. For instance, Flex wants:
>
<mx:DataGrid id="dg" dataProvider="">
<mx:columns>
         <mx:DataGridColumn dataField="column1" />
         <mx:DataGridColumn dataField="column2" />
          
         <mx:DataGridColumn dataField="columnN" />
      </mx:columns>
</mx:DataGrid>
>
I need to create this table-like array in Java and have it readable
as a dataprovider by flex. I know about ArrayCollections and Java
ArrayLists can be nicely converted to this in Flex, but I just don't
know how to create them with a column1, column2, etc. when I don't
know from query to query how many columns will be in my results.
>
Any help would be greatly appreciated!
>

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k1ng87 wrote:
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The web site you are accessing has experienced an unexpected
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SQLSTATE
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Browser Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1;
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Access database query resultset in java scriptlet

Question:
1) I am Creating a web page and plotting points on the page:
2) Database query results in decimal values dec_latitude and dec_longiitude.
3) Perform calculations on lati. & long. in a java scriptlet to create a plot position (xpos, ypos).
4) Send the xpos and ypos back to the java server page
5) Use <IMG and absolute positioning to plot the point at position xpos, and ypos.
6) Repeat until all rows in the query result set have been plotted.
I don't know how to pass the dec_latitude and dec_longitude to the java scriptlet.
After the java scriptlet calculation translates the latitude and longitude
into xpos and ypos, I need to pass the xpos and ypos back to the java server page so that a data point is plotted on a map at position xpos, ypos.
I tried many ways of doing it but am just guessing as
to how to pass the data.
Thanks in Advance. - John
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<c:set var="latvar" value="${row.dec_latitude}" scope="page"/>
<c:set var="longvar" value="${row.dec_longitude} "scope="page" />
*** java code scriptlet - ***
*** convert latitude and longitude to xpos and ypos for display ***
<%
latitude = (Float)pageContext.getAttribute("latvar"); <--- runtime error !!!!
longitude = (Float)pageContext.getAttribute("longvar");
xpos = (int)Math.round(latitude);
ypos = (int)Math.round(longitude);
xpos = 1082 - xpos;
ypos = 700 + ypos;
pageContext.setAttribute("xpos", xpos);
pageContext.setAttribute("ypos", ypos);
%>
*** plot a point on the display html page overlaying the map ***
<IMG ID="Row" SRC="smallredbox.jpg" ALT="red box"
STYLE="position:absolute;
top:<%=xpos%> px;
left:<%=ypos%> px;
z-index:2">
</c:forEach>

Thanks
I still get a runtime error: I translated the code you gave to code below .... which I think is equivalent. See Below: I'm still learning about this stuff so I may not have not translated this properly. Do
you see what I am doing wrong?
Best Regards,
- John
%@ page language="java" contentType="text/html;
charset=ISO-8859-1"%>
<%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ page import="java.lang.Math"%>
<sql:setDataSource dataSource="jdbc/SampleDB" />
<c:set var="genus_name" value="${param.genus_name}" />
<c:set var="species_name" value="${param.species_name}" />
<c:set var="species_common_name" value="${param.species_common_name}" />
<c:set var="dd_sighted" value="${param.dd_sighted}" />
<c:set var="mm_sighted" value="${param.mm_sighted}" />
<c:set var="yyyy_sighted" value="${param.yyyy_sighted}" />
<c:set var="species_state" value="${param.species_state}" />
<c:set var="species_county" value="${param.species_county}" />
<c:set var="species_country" value="${param.species_country}" />
<c:set var="dec_latitude" value="${param.dec_latitude}" />
<c:set var="dec_longitude" value="${param.dec_longitude}" />
<c:set var="notes" value="${param.notes}" />
<c:set var="person_first_name" value="${param.person_first_name}" />
<c:set var="person_last_name" value="${param.person_last_name}" />
<c:set var="person_street" value="${param.person_street}" />
<c:set var="person_city" value="${param.person_city}" />
<c:set var="person_state" value="${param.person_state}" />
<c:set var="person_zip" value="${param.person_zip}" />
<c:set var="person_country" value="${param.person_country}" />
<c:set var="person_email" value="${param.person_email}" />
<h2>Species Sightings:</h2>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Breckenridge Citizen Bio-Survey Selective Output Page</title>
</head>
<body>
Izaak Walton League of America
<h1>Breckenridge Citizen Bio-Survey Selective Output</h1>
<HR>
<c:if test="${param.action == 'Submit'}">
<%int xpos = 0;
     int ypos = 0;
     float latitude = 0.0F;
     float longitude = 0.0F;
     float latitudeMpls = 45.06F;
     float longitudeMpls = -93.14F;                    int xposMpls = 1205 - (int) Math.round(latitudeMpls);
     int yposMpls = 735 + (int) Math.round(longitudeMpls);
%>
<IMG SRC="minnesota_1990.jpg" ALT="minesota map" style="z-index:1;"> <----- THIS WORKS FINE
<IMG ID="Row" SRC="smallredbox.jpg" ALT="red box"
STYLE="position:absolute;
top:<%=xposMpls%> px;
left:<%=yposMpls%> px;
z-index:2"> <----- THIS WORKS FINE FOR HARDCODED MPLS XPOS AND YPOS
<sql:query var="qryBio">
SELECT
PERSON_FIRST_NAME,
PERSON_LAST_NAME,
GENUS_NAME,
SPECIES_NAME,
SPECIES_COMMON_NAME,
SPECIES_COUNTY,
SPECIES_STATE,
SPECIES_COUNTRY,
DD_SIGHTED,
MM_SIGHTED,
YYYY_SIGHTED,
DEC_LATITUDE,
DEC_LONGITUDE,
NOTES,
ENTRY_TIMESTAMP
FROM app.biosurvey where
genus_name like rtrim(upper('${genus_name}')) AND
species_name like rtrim(upper('${species_name}')) AND
species_common_name like rtrim(upper
('${species_common_name}')) AND
species_state like rtrim(upper('${species_state}')) AND
species_county like rtrim(upper('${species_county}')) AND
species_country like rtrim(upper('${species_country}')) AND
person_first_name like rtrim(upper('${person_first_name}')) AND
person_last_name like rtrim(upper('${person_last_name}')) AND
person_email like rtrim(upper('${person_email}'))
</sql:query>
<c:forEach var="row" items="${qryBio.rows}">
<--- THE LINE ABOVE WORKS FINE --->
<c:set var="latvar" value="${row.dec_latitude}" scope="page" />
<c:set var="longvar" value="${row.dec_longitude} " scope="page" />
<%
latitude =
Float.parseFloat((String)pageContext.getAttribute("latvar"));
<--- RUNTIME ERROR OCCURS HERE --- SEE LINE ABOVE --->
longitude =
Float.parseFloat((String)pageContext.getAttribute("longvar"));
xpos = (int) Math.round(latitude);
ypos = (int) Math.round(longitude);
xpos = 1082 - xpos;
ypos = 700 + ypos;
request.setAttribute("xpos",new Integer(xpos));
request.setAttribute("ypos",new Integer(ypos));
%>
IIMG ID="Row" SRC="smallredbox.jpg" ALT="red box"
STYLE="position:absolute;
top:<%=xpos%> px;
left:<%=ypos%> px;
z-index:2">
<--- THIS (ABOVE) WORKS FINE WITH CORRECT VALUES FOR XPOS AND YPOS WHEN RUNTIME ERROR DOES NOT OCCUR --->
</c:forEach>
</c:if>

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