限制 FreeMarker 中的字符串长度

Question

I'm trying to get a substring from a string in FreeMarker. However there are 2 thigns to consider:

1. The string can be null
2. The string can be shorter then the maximum string length

I do the following:

<#list landingpage1.popularItems as row>
    <li>
        <span class="minititle">
            <#assign minititle=(row.title!"")>
            <#if minititle?length &lt; 27>
                ${minititle}
            <#else>
                ${minititle?substring(0,26)} ...
            <#/if>
        </span>
    </li>
</#list>

I get a freemarker error saying:

Failed to load templates: Encountered "</#list>" at line 144, column 65 in landingpage1.ftl.
Was expecting one of:
    <ATTEMPT> ...
    <IF> ...
    <LIST> ...
    <FOREACH> ...
    <SWITCH> ...
    <ASSIGN> ...
    <GLOBALASSIGN> ...
    <LOCALASSIGN> ...
    <INCLUDE> ...
    <IMPORT> ...
    <FUNCTION> ...
    <MACRO> ...
    <TRANSFORM> ...
    <VISIT> ...
    <STOP> ...
    <RETURN> ...
    <CALL> ...
    <SETTING> ...
    <COMPRESS> ...
    <COMMENT> ...
    <TERSE_COMMENT> ...
    <NOPARSE> ...
    <END_IF> ...
    <BREAK> ...
    <SIMPLE_RETURN> ...
    <HALT> ...
    <FLUSH> ...
    <TRIM> ...
    <LTRIM> ...
    <RTRIM> ...
    <NOTRIM> ...
    <SIMPLE_NESTED> ...
    <NESTED> ...
    <SIMPLE_RECURSE> ...
    <RECURSE> ...
    <FALLBACK> ...
    <ESCAPE> ...
    <NOESCAPE> ...
    <UNIFIED_CALL> ...
    <WHITESPACE> ...
    <PRINTABLE_CHARS> ...
    <FALSE_ALERT> ...
    "${" ...
    "#{" ...

Very odd. Can anybody help?

Answer 1

The error magically solved itself after extensive testing. Must be karma.

My final code for safe checking:

<#assign minititle=(row.title!"")>
<#if minititle?length &lt; 27>
${minititle}
<#else>
${minititle?substring(0,26)} ...
</#if>

Hope it helps somebody else

Answer 2

I'm sure you're happy it's working now, but the error you were receiving had nothing to do with your String Truncation Code, it's because your </#if> is incorrect.

<#if condition >
    This Is Correct
</#if>


<#if condition >
    This Will Show An Error
<#/if>

Answer 3

an even easier solution without using if-else

${minititle?left_pad(26)[0..*26]}

this will - first insert white space on left to ensure the string is at least 26 char long (if the string is short than 26 char) - truncate string to exact 26 char long (if the string is longer than 26 char)

I've tried and it worked well with VERSION 2.3.24

Answer 4

As of Freemarker 2.3.29 (released 2019-08-17) there is a new built-in called truncate. Per the release notes :

string?truncate(length) truncates the text to the given length, and by default adds [...] at the end if truncation has happened. Truncation happens at word boundaries, unless the result is too short that way, in which case it falls back to truncation mid word. There's also?truncate_w to force Word Boundary truncation, and?truncate_c (for Character Boundary) that doesn't care about word boundaries.

So the question can now be solved simply like

${minititle?truncate(26)}