How do I avoid hardcoding column names with SQL taglib

[Robert Kostes]

I created a JSP file along the lines of:

<%!
public static final String TABLE_SYSDEFAULTS = "app.systemDefaults";

public static final String COL_X = "x";
%>

I then include this in my JSP pages. My update of the table is very clean:

<sql:update var="rowsUpdated">
UPDATE <%=TABLE_SYSDEFAULTS%>
SET <%=COL_X%>='<%=request.getParameter("whatever")%>'
WHERE ID=1
</sql:update>

However, I cannot figure out how to use the constant on the query.

<sql:query var="qrySD" >SELECT * FROM <%=TABLE_SYSDEFAULTS%></sql:query>
<c:forEach var="row" items="${qrySD.rows}">
<c:set var="rowId" value="${row.x}"/>
...

How can I use row.COL_X rather than hardcoding the column name?

Robert

[Paul Clapham]

Well, for a start I wouldn't mix scriptlets with JSTL. In fact I wouldn't use scriptlets at all. I would do this to declare the column name:

<c:set var="columnName" value="x" />

and then I would do this to access it:

<c:set var="rowId" value="${row[columnName]}"/>

Or something like that -- I'm not really familiar with the SQL tags. A proper solution to this question would involve not using JSP at all, since none of what you are doing there has anything to do with generating HTML. It should really be done in a servlet, or in some other component called from a servlet.

[Bear Bibeault]

Be aware that even the framers of the JSTL Specification recommend against using the SQL tags in a JSP for anything other than quick prototype code.

[Robert Kostes]

Thanks for the quick responses. I am generating HTML but I did not want to bore you with the details.

I got rid of the SQL tags and am using straight Java and HTML. It is much longer code but it all works nicely.
The combination of Java and HTLM is not as ugly as I thought it would be.

thanks
Robert

[Bear Bibeault]

No one said not to use JSP -- just avoid the SQL tags (and Java scriptlets) in a JSP.

[Robert Kostes]

I didn't literally mean straight Java. I just meant JSP without the tags.

thanks
Robert