Freemarker模板错误:null或丢失 [英] Freemarker template error: null or missing
问题描述
public static void main(String[] args) throws IOException {
port(8080);
Configuration config = new Configuration(Configuration.VERSION_2_3_26);
config.setDirectoryForTemplateLoading(new File("PATH_NAME"));
get("/test", (req,res) ->{
StringWriter writer = new StringWriter();
Template temp = config.getTemplate("loginform.ftl");
temp.process(null, writer);
return writer;
});
post("/select", (req,res) -> {
String city = req.queryParams("city");
String state = req.queryParams("state");
Map<String, Object> data = new HashMap<>();
data.put("Hello", "Your not null!");
StringWriter writer = new StringWriter();
Template temp = config.getTemplate("result.ftl");
temp.process(data, writer);
return writer;
});
}
以上是我正在开发的Spark应用程序的主要方法.它涉及两个模板，loginform.ftl和result.ftl. Loginform.ftl是一个简单的html表单，它向服务器发送发布请求，该请求由上述代码中的发布处理程序处理.当我填写表格并发送请求时，出现500个内部服务器错误.该错误与result.ftl有关，目前，我正在使用此结果来测试模板制作.我正在将HashMap传递给result.ftl模板.我得到的错误是:
Above is the main method to the Spark application i am developing. It involves two templates, loginform.ftl and result.ftl. Loginform.ftl is a simple html form that sends a post request to the server which handled by the post handler in the code above. When I fill out the form and send the request, i get a 500 internal server error. The error relates to the result.ftl which, right now, i am using to test template making. I am passing a HashMap to the result.ftl template. The error i get is:
FreeMarker template error:
The following has evaluated to null or missing:
==> data [in template "result.ftl" at line 2, column 8]
FTL stack trace ("~" means nesting-related):
- Failed at: #list data as key, value [in template "result.ftl" at line
2, column 1]
----
我认为这是指在生成模板时数据为null，但显然不是.我不知道这正在发生.我的模板文件在下面.
loginform.ftl
I took this to mean that data was null when the template was being generated , but it very clearly isn't. I have no idea this is happening. My template files are below.
loginform.ftl
<form action= "/select" method= "POST" accept-charset="utf-8">
City Name: <input type= "text" name = "city">
State(2 letter format):<input type= "text" name = "state">
<input type= "submit" id = "submitButton">
</form>
result.ftl
result.ftl
<html>
<#list data as key, value>
${key} = ${value};
</#list>
</html>
推荐答案
错误消息正确.在您的Java代码中，data用作数据模型的根.根本身不是顶级变量，而是顶级变量的容器.因此，例如${Hello}将起作用，并显示"Your not null！". (还要注意，数据"只是一个局部变量名，在Java编译过程中就消失了，并且您永远不要将数据"变量名传递给FreeMarker.)因此，您应该制作一个root Map(或bean) ，将data Map(或bean)放入其中，然后将root传递给Template.process.
The error message is right. In your Java code data is used as the data-model root. The root itself is not a top-level variable, but the container of the top-level variables. So for example ${Hello} would work, and print "Your not null!". (Also note that "data" is just a local variable name, which is gone during Java compilation, and you never pass the "data" variable name to FreeMarker.) So you should make a root Map (or bean), put the data Map (or bean) into it, and pass root to Template.process.
更新:也就是说，现在您拥有temp.process(data, writer);的地方，您应该拥有:
Update: That is, where now you have temp.process(data, writer);, you should have:
Map<String, object> root = new HashMap<>();
root.put("data", data);
temp.process(root, writer);
这篇关于Freemarker模板错误:null或丢失的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
