Truncating returned data in Dust.js template

Question

We are outputting into a Dust.js template, like so:

{#Data}
<li class="link-block clearfix">
    <img class="profile-image" src="{ImagePath}"/>
    <div class="left">
        <a href="{UrlPath}">
            <span class="left">
                <span class="details">{ByLineStart}{ByLineAction}{ByLineEnd}</span>
                <p>{Detail}</p>
            </span>
            <span class="left info">
                <span class="last-reply">{Last}</span>
                <span class="count-small">{ChildCount}</span>
            </span>
        </a>
    </div>
</li>
{/Data}

We want to make the "Detail" output truncated in this case at XXX number of characters. Like an RSS feed, the whole block is a clickable area that takes a user into another part of the application. Does anybody have any knowledge of existing Dust Logic that will truncate the value in-line?

Answer 1

None that I know of. But you can try the following

Creating custom helper

var dust = require("dustjs-linkedin");
require("dustjs-helpers");
dust.helpers.Truncate = function(chunk, context, bodies, params) {
    var data   = dust.helpers.tap(params.data, chunk, context),
        length = dust.helpers.tap(params.length, chunk, context);
    return chunk.write(data.substr(0, length));
}

Template

{@Truncate data="{Detail}" length="15"/}

If the value XXX you specified in the question is a constant value, then you can create a custom filter like this. In this example XXX is taken as 5.

var dust = require("dustjs-linkedin");
dust.filters.t = function(value){
    return value.substr(0, 5);
};

Template

{Detail|t}