试图生成一个在freemarker中变成变量名称的字符串或“派生变量名称”的字符串。

发布于 2025-02-01 05:34:18 字数 1111 浏览 4 评论 0原文

我正在使用数据指导性或列表来吸收几个值，其中我不知道会有多少个值，我想尝试通过它们列表，并在列表中创建几个变量，如果您愿意的话。

<#list 1..10 as x>
<#-- the next line doesn't work, but what i'm trying to fix -->
<#assign .vars['VAR'+x?string] = rand(100) />
</#list>

但是我可以以这种方式列出它们。

<#list 1..10 as x>
    ${.vars['VAR'+x?string]}
</#list>

分配的文档说：

名称：变量的名称。这不是表达。但是，可以是以字符串字面形式写成，如果变量名称很有用包含保留的字符，例如＆lt; #ashign“ foo-bar” = 1＆gt;。请注意，该字符串文字不会扩展插值（如 “ $ {foo}”）。

没有办法解决这个问题吗？我想做不可能的事情吗？有什么方法可以将派生名称插入.vars ...哈希是吗？

更多的研究很接近，但没有让我到那里：

这个prevoius问题给出了如何读取派生变量的方法，但是我需要写/创建派生的变量。
这个prevoius问题表明，我可以使用字符串来分配变量，并重新介绍我们在第一个链接中看到的内容。 freemarker模板中的变量名称

原文

I'm using a data-directive or list to pull in several values, of which, I don't know how many there will be, and I want to try and list through them, and create several variables in the list if you will.

<#list 1..10 as x>
<#-- the next line doesn't work, but what i'm trying to fix -->
<#assign .vars['VAR'+x?string] = rand(100) />
</#list>

But I can list them back out that way.

<#list 1..10 as x>
    ${.vars['VAR'+x?string]}
</#list>

The documentation for assign, says:

name: name of the variable. It is not expression. However, it can be
written as a string literal, which is useful if the variable name
contains reserved characters, for example <#assign "foo-bar" = 1>.
Note that this string literal does not expand interpolations (as
"${foo}").

Is there no way around this? Am I trying to do the impossible? Is there some way I can insert a derived name into the .vars... Hash is it?

A little more research that was close, but didn't get me there:

This prevoius question gives how to READ the derived variable, but I need to WRITE/CREATE the derived variable.
FreeMarker get variable value by concatenating another variable value
This prevoius question shows that I can use a string to assign a variable and re-iterates what we saw in the first link.
Variable name in Freemarker Template Language

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病毒体 2025-02-08 05:34:19

最终，我相信我的解决方案的正确方法是一系列哈希：

<#list 1..z_Coupon_Pet.NUM_COUPONS as x>
    <#assign INSTORE_COUPON=call_coupon_from_table1() />
    <#assign ONLINE_COUPON=call_coupon_from_table2() />
    <#assign coupon_string_row= '{
    "COUPON_NUM" : ${x},
    "INSTORE" : "${INSTORE_COUPON?js_string}",
    "ONLINE" : "${ONLINE_COUPON?js_string}"
}' />
<#if x==1>
   <#assign coupon_hash_string = coupon_string_row />
<#else>
   <#assign coupon_hash_string = coupon_hash_string + ',' + coupon_string_row />
</#if>
</#list>
</#if>
<#if coupon_hash_string?has_content>
   <#assign coupon_hash=parsejson('[' + coupon_hash_string + ']') />
</#if>

我们特别避免＆lt; #assign my_hash = my_hash + element/＆gt;，因为此注释在文档中：

请注意，哈希串联不适用于许多重复的串联，例如将项目添加到循环中的哈希中。虽然将哈斯添加在一起是快速的，并且是恒定的时间（与添加的哈希的尺寸无关），但所得的哈希读数比添加的哈希速度要慢一些。因此，在添加的添加之后，结果可以不切实际地读取。

Ultimately, I believe the correct way to phrase my solution was a sequence of hashes:

<#list 1..z_Coupon_Pet.NUM_COUPONS as x>
    <#assign INSTORE_COUPON=call_coupon_from_table1() />
    <#assign ONLINE_COUPON=call_coupon_from_table2() />
    <#assign coupon_string_row= '{
    "COUPON_NUM" : ${x},
    "INSTORE" : "${INSTORE_COUPON?js_string}",
    "ONLINE" : "${ONLINE_COUPON?js_string}"
}' />
<#if x==1>
   <#assign coupon_hash_string = coupon_string_row />
<#else>
   <#assign coupon_hash_string = coupon_hash_string + ',' + coupon_string_row />
</#if>
</#list>
</#if>
<#if coupon_hash_string?has_content>
   <#assign coupon_hash=parsejson('[' + coupon_hash_string + ']') />
</#if>

We specifically avoid <#assign my_hash = my_hash + element /> because of this note in the documentation:

Note that hash concatenation is not to be used for many repeated concatenations, like for adding items to a hash inside a loop. While adding together hashes is fast and is constant time (independent of the size of the hashes added), the resulting hash is a bit slower to read than the hashes added together. Thus after tens... of additions the result can be impractically slow to read.

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屋檐 2025-02-08 05:34:18

由于freemarker无法分配收集元素（但是您可以？map（IT - ＆gt; ...）收集到另一个集合），因此唯一的方法是通过？drigent drigent ：

<#list 1..10 as x>
<#-- the next line doesn't work, but what i'm trying to fix -->
<@'<#assign VAR${x?c} = rand(100)>'?interpret />
</#list>

我想知道为什么您需要分配给动态命名的变量，因为即使较小的变量，动态命名的变量也很痛苦。

As FreeMarker can't assign to elements of collections (but you can ?map(it -> ...) a collection to another), the only way is via ?interpret:

<#list 1..10 as x>
<#-- the next line doesn't work, but what i'm trying to fix -->
<@'<#assign VAR${x?c} = rand(100)>'?interpret />
</#list>

I wonder why do you need to assign to a dynamically named variables though, since reading dynamically named variables is also a pain, even if a lesser one.

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