Display table rows using JSTL with different colors based on condition

[namita sasa]

I need to display a table using jstl. The columns are id, tie_id, comments.
id is the primary key in table. I want to display rows having same tie_id with same color.
How can I write jstl loop for this?

[Bear Bibeault]

Assign a CSS class name to the <tr> element for the row that's distinct for each distinct value.

The class name can be used to assign different background colors.

[namita sasa]

Each row tie_id may not be different. For example, first three rows will have same tie_id=1, next two will have same tie_id=2 etc.
I need to compare tie_id of each row using jstl.

[Bear Bibeault]

Comparisons are easy; use the == (or eq) operator.

[Mark E Hansen]

How many different tie_id values might you have? 3? 47? 1023? 1048576?
If you're going to come up with a unique color for each unique tie_id, will you have enough colors?

Are the records going to be grouped by tie_id? If not, should they be?

If they are grouped by tie_id, then can't you just alternate colors between different sets of tie_id values, as in:

  row   1    tie_id=1         color=blue
  row   2    tie_id=1         color=blue
  row   3    tie_id=1         color=blue
  row   4    tie_id=2         color=silver
  row   5    tie_id=3         color=blue

[namita sasa]

Thanks for your replies Mark and Bear. I don't know in future how many tie_id's will be there. So, I am going to repeat the colors. I have set color array of string in session having 10 colors. After the 10'th color, again the first color repeats and so on.
The records are grouped by tie_id. I have set following loop and getting error message. I am taking value of tie_id of first row=first_tieId and then compare it with tie_id of other records. If tie_id are different, a new color will be set.

 
<table>
<c:set var="first_tieId" value="${table[0].tie_id}" />  
<c:set var="i" value="0" />

<c:set var="color" value="${color[i]}" />

 
    <c:forEach var="record" items="${table}">
		
		<c:set var="tieId" value="${record.tie_id}" />
			
                      <c:if test="${tieId!=first_tieId}" >
				       <c:set var="first_tieId" value="${tieId}" />
			      
					<c:set var="color" value="${color[i+1]}" />
				       <c:set var="i" value="${i+1}" /> 
				     <c:if test="${i==10}">
				           <c:set var="i" value="0" />
                                    </c:if>		
			</c:if>
                    <tr>
                      <td scope="row" bgcolor="<c:out value="${color}"/>">${record.club_name}</td>
                      <td scope="row" bgcolor="<c:out value="${color}"/>">${record.club_status}</td>
                      <td scope="row" bgcolor="<c:out value="${color}"/>">${record.timestamp}</td>
                   </tr>
    </c:forEach>
</table>
   

Erroe Message : Unable to find a value for "1" in object of class "java.lang.String" using operator "[]"

Please help!

[namita sasa]

I am getting stuck because I am not able to access the color array in JSP which is in session scope.

  <c:set var="color" value="${color[i+1]}" />  

Help!

[Mark E Hansen]

How did you create this array and place it in the session scope (show the code that did this).

[namita sasa]

I got the answer. I just accessed it using ${sessionScope.color[i]} and it worked. Thanks again you all!!

[Mark E Hansen]

namita sasa wrote:I got the answer. I just accessed it using ${sessionScope.color[i]} and it worked. Thanks again you all!!

Yes, but then you're setting another variable called color? Won't this be confusing?
Perhaps you could call one color_list?

[Kris Schneider]

When you do this:

<c:set var="color" value="${color[i]}" />

You're basically hiding the session-scoped var with a page-scoped var (when you use unqualified access to color). Use a different name, like:

<c:set var="rowcolor" value="${color[i]}" />
...
<c:set var="rowcolor" value="${color[i+1]}" />
...
<td scope="row" bgcolor="<c:out value="${rowcolor}"/>">${record.club_name}</td>

[namita sasa]

Ok. I got what you said. I will change the names of page scope and session scope variables.

Thanks.