FreeMarker-handeling Json包含int

Question

我试图创建一个脚本，它将检查id并导出它的名称，但我遇到了以下情况；

FTL堆栈跟踪（“~”表示与嵌套相关）：

<#list [services] as st><#if st.externalId == externalId>${st.name}</#if>
<#list st.children as nd<#if nd.externalId == externalId>${nd.name}</#if>
<#list nd.children as rd><#if rd.externalId == externalId>${rd.name}</#if>
<#list rd.children as th><#if th.externalId == externalId>${th.name}</#if>
<#list th.children as ths><#if ths.externalId == externalId>${ths.name}</#if>
<#list ths.children as thb><#if thb.externalId == externalId>${thb.name}</#if>
</#list></#list></#list></#list></#list></#list>`    

<#assign services=
{
"externalId": 1,
"name": "one",
"children": [
    {
        "externalId": 2,
        "name": "two",
        "children": [ 
            {
                "externalId": null,
                "name": "three",
                "children": [
                   {
                             "externalId": 4,
                             "name": "four",
                             "children": [
                                {
                                         "externalId": 5,
                                         "name": "five",
                                         "children": []
                                }         ]
                    }       ]
            }]
     }]
}>      

请帮忙！！

Answer 1

在FreeMarker中，您（几乎）总是必须指定一个默认值，希望null-s出现。比如:nd.externalid！==external将在null的情况下将nd.externalid视为空字符串。或者，当th.name为null时，${th.name！'null'}将打印null。