Freemarker无法从列表中获取对象值(Freemarker cannot get object value from the list)
我使用最新的freemarker版本2.3.23我有包含User对象的列表，User对象很简单，只包含name属性。 我的ftl文件显示如下：
<#list userlist> <#items as item> ${item.name} </#items>我的Java代码如下所示：
public static void main(String[] args) throws Exception { List<User> user = new ArrayList<User>(); User user1 = new User(); User user2 = new User(); user1.setName("jason"); user2.setName("tony"); user.add(user1); user.add(user2); Map<String, Object> params = new HashMap<String, Object>(); params.put("userlist", user); Template template = FreemarkerUtil.getTemplate(FreemarkerUtil.TEMPLATE_PATH, "test.ftl"); FileWriter fw = null; try { fw = new FileWriter(new File(FreemarkerUtil.getProjOutputDomainPath() + "test.txt")); template.process(params, fw); } catch (Exception e) { e.printStackTrace(); } finally { if (fw != null) { fw.close(); } } } class User { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } }错误显示如下：
The following has evaluated to null or missing: ==> item.name [in template "test.ftl" at line 3, column 19]`enter code here` Tip: It's the step after the last dot that caused this error, not those before it. Tip: If the failing expression is known to be legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)?? FTL stack trace ("~" means nesting-related): - Failed at: ${item.name} [in template "test.ftl" at line 3, column 17] Java stack trace (for programmers): freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...] at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:131) at freemarker.core.EvalUtil.coerceModelToString(EvalUtil.java:355) at freemarker.core.Expression.evalAndCoerceToString(Expression.java:82) at freemarker.core.DollarVariable.accept(DollarVariable.java:41) at freemarker.core.Environment.visit(Environment.java:324) at freemarker.core.MixedContent.accept(MixedContent.java:54) at freemarker.core.Environment.visitByHiddingParent(Environment.java:345) at freemarker.core.IteratorBlock$IterationContext.executeNestedBlockInner(IteratorBlock.java:268) at freemarker.core.IteratorBlock$IterationContext.executeNestedBlock(IteratorBlock.java:220) at freemarker.core.IteratorBlock$IterationContext.loopForItemsElement(IteratorBlock.java:207) at freemarker.core.Items.accept(Items.java:43) at freemarker.core.Environment.visitByHiddingParent(Environment.java:345) at freemarker.core.IteratorBlock$IterationContext.executeNestedBlockInner(IteratorBlock.java:276) at freemarker.core.IteratorBlock$IterationContext.executeNestedBlock(IteratorBlock.java:220) at freemarker.core.IteratorBlock$IterationContext.accept(IteratorBlock.java:194) at freemarker.core.Environment.visitIteratorBlock(Environment.java:572) at freemarker.core.IteratorBlock.acceptWithResult(IteratorBlock.java:78) at freemarker.core.IteratorBlock.accept(IteratorBlock.java:64) at freemarker.core.Environment.visit(Environment.java:324) at freemarker.core.Environment.process(Environment.java:302) at freemarker.template.Template.process(Template.java:325) at auto.freemarker.template.MySQLGenerator.main(MySQLGenerator.java:61)I use the latest freemarker version 2.3.23 I have list which contains the User object, User object is simple which only contains the name property. My ftl file show like below:
<#list userlist> <#items as item> ${item.name} </#items>My Java Code show like below:
public static void main(String[] args) throws Exception { List<User> user = new ArrayList<User>(); User user1 = new User(); User user2 = new User(); user1.setName("jason"); user2.setName("tony"); user.add(user1); user.add(user2); Map<String, Object> params = new HashMap<String, Object>(); params.put("userlist", user); Template template = FreemarkerUtil.getTemplate(FreemarkerUtil.TEMPLATE_PATH, "test.ftl"); FileWriter fw = null; try { fw = new FileWriter(new File(FreemarkerUtil.getProjOutputDomainPath() + "test.txt")); template.process(params, fw); } catch (Exception e) { e.printStackTrace(); } finally { if (fw != null) { fw.close(); } } } class User { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } }Error shows below:
The following has evaluated to null or missing: ==> item.name [in template "test.ftl" at line 3, column 19]`enter code here` Tip: It's the step after the last dot that caused this error, not those before it. Tip: If the failing expression is known to be legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)?? FTL stack trace ("~" means nesting-related): - Failed at: ${item.name} [in template "test.ftl" at line 3, column 17] Java stack trace (for programmers): freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...] at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:131) at freemarker.core.EvalUtil.coerceModelToString(EvalUtil.java:355) at freemarker.core.Expression.evalAndCoerceToString(Expression.java:82) at freemarker.core.DollarVariable.accept(DollarVariable.java:41) at freemarker.core.Environment.visit(Environment.java:324) at freemarker.core.MixedContent.accept(MixedContent.java:54) at freemarker.core.Environment.visitByHiddingParent(Environment.java:345) at freemarker.core.IteratorBlock$IterationContext.executeNestedBlockInner(IteratorBlock.java:268) at freemarker.core.IteratorBlock$IterationContext.executeNestedBlock(IteratorBlock.java:220) at freemarker.core.IteratorBlock$IterationContext.loopForItemsElement(IteratorBlock.java:207) at freemarker.core.Items.accept(Items.java:43) at freemarker.core.Environment.visitByHiddingParent(Environment.java:345) at freemarker.core.IteratorBlock$IterationContext.executeNestedBlockInner(IteratorBlock.java:276) at freemarker.core.IteratorBlock$IterationContext.executeNestedBlock(IteratorBlock.java:220) at freemarker.core.IteratorBlock$IterationContext.accept(IteratorBlock.java:194) at freemarker.core.Environment.visitIteratorBlock(Environment.java:572) at freemarker.core.IteratorBlock.acceptWithResult(IteratorBlock.java:78) at freemarker.core.IteratorBlock.accept(IteratorBlock.java:64) at freemarker.core.Environment.visit(Environment.java:324) at freemarker.core.Environment.process(Environment.java:302) at freemarker.template.Template.process(Template.java:325) at auto.freemarker.template.MySQLGenerator.main(MySQLGenerator.java:61)
原文：https://stackoverflow.com/questions/34503918
更新时间：2022-04-21 13:04
最满意答案
I ended using a custom template filter:
@register.filter @stringfilter def datedate(value,format="%d/%m/%Y"): try: return parse_datetime(value).strftime(format) except Exception as e: return ""So when I did
{{mydate|datedate}}it shows "22/03/2016"Thank you all for your help.
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