请问FreeMarket 能不能在页面上直接点出对象的集合或数组的字段

遇到一个问题不知道怎么直接点对象点的集合或数组的字段
public class CalenderCell {
private Collection performIds;
private String smallPic;
//getter/setter方法略^-^
}
下面是报错的部分
[color=red][/color]

报下面的错误

2009-01-19 10:50:36,468 ERROR [freemarker.runtime] - <>
Error on line 39, column 85 in movieCalendar.ftl
Expecting a string, date or number here, Expression cells[x - firstDate].performIds is instead a freemarker.template.SimpleSequence

The problematic instruction:

==> ${cells[x - firstDate].performIds} [on line 39, column 83 in movieCalendar.ftl]

Java backtrace for programmers:

freemarker.core.NonStringException: Error on line 39, column 85 in movieCalendar.ftl
Expecting a string, date or number here, Expression cells[x - firstDate].performIds is instead a freemarker.template.SimpleSequence
at freemarker.core.Expression.getStringValue(Expression.java:126)
at freemarker.core.Expression.getStringValue(Expression.java:93)
at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
at freemarker.core.Environment.visit(Environment.java:208)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:208)
at freemarker.core.IfBlock.accept(IfBlock.java:82)
at freemarker.core.Environment.visit(Environment.java:208)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:208)
at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:179)
at freemarker.core.Environment.visit(Environment.java:415)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)
at freemarker.core.Environment.visit(Environment.java:208)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:208)
at freemarker.core.Environment.process(Environment.java:188)
at freemarker.template.Template.process(Template.java:232)
at com.uchacha.core.movieCalendar.template.FMWriter.process(FMWriter.java:60)
at com.uchacha.core.movieCalendar.template.FMWriter.write(FMWriter.java:43)
at com.uchacha.core.movieCalendar.template.CalanderWriter.main(CalanderWriter.java:98)

Error on line 39, column 85 in movieCalendar.ftl
Expecting a string, date or number here, Expression cells[x - firstDate].performIds is instead a freemarker.template.SimpleSequence

The problematic instruction:

==> ${cells[x - firstDate].performIds} [on line 39, column 83 in movieCalendar.ftl]

Java backtrace for programmers:

请问有没有遇到过类似的问题并怎么解决的啊?

你的Collection里面的元素是字符？
你是想生成这样的数据？12,32,42,55,43,65？

那你可以给CalenderCell加个方法嘛。比如是performIdsToString()，其中去迭代组合数据咯。
然后freemarker里调用咯。

freemarker的读集合好像就这个。
<#list employees as e>
${e_index}. ${e.name}
</#list>