How would you embed atomic partials into a template data object - json

Question

I'm using handlebars and assemble with yeoman and gulp.
I want to have some globalized partials that are able to be nested or injected into another partial by calling it within the context of a data object.
A simple example of that would be having a list of links that I could reference inside content throughout the site. The reason behind this, is the need for consistency. If for example, if I have a link within text on a page that I reference a 15 times throughout an entire website, but then realize I need to add a trade mark or modify the text, I want to update it once, not 15 times.
This is an example of what I want to do. Define global data inside a json file:
links.json
{
"apple": {
"linktext": "apple",
"target": "_blank",
"href": "http://www.apple.com"
},
"blog-article-foo-bar": {
"linktext": "foo bar",
"href": "http://www.foobar.com"
},
"dell": {
"linktext": "dell",
"target": "_parent",
"href": "http://www.dell.com"
}
}
Generate a partial from that content using a simple or complex template:
links.hbs
<a href="{{href}}" {{#if target}}target="{{target}}"{{/target}}>{{linktext}}</a>
And be able to embed that partial into another one by referencing it some how. This didn't work, but I've been reading about custom helpers, but can't figure out how I would intercept the partial and bind it into the other partial.
text.json
{
"text": "If you need a computer, go to {{> link link.apple}}."
}
text.hbs
<p>
{{text}}
</p>
compiled.html
<p>
If you need a computer, go to apple.
</p>
If you have suggestions or examples that might help me understand how to achieve this, I'd really appreciate the support. Thanks in advance.

Answer 1

There is some information about Handlebars helpers in their docs but not that much.
Since you're trying to use handlebars syntax in the value of a property on the context (e.g. text), handlebars won't render the value since it's already rendering the template. You can create your own helper that can render the value like this:
Handlebars.registerHelper('render', function(template, options) {
// first compile the template
const fn = Handlebars.compile(template);
// render the compiled template passing the current context (this) to
// ensure the same context is use
const str = fn(this);
// SafeString is used to allow HTML to be returned without escaping it
return new Handlebars.SafeString(str);
});
Then you would use the helper in your templates like this:
{{render text}}

Answer 2

Thanks for the example #doowb, your code did work but not for what I was trying to do. I really wanted something more complicated but I simplified my question not knowing it would be an issue. The code you provided worked (I think after a slight tweak) for a simple render of a template, but my templates use helpers such as #each and #if which caused the issue. Where the helpers were in my template, I ended up getting async placeholders. For example: <a $ASYNC$1$3...> I later learned this has to do with how partials are rendered. Understanding that lead me to subexpressions and the below solution.
Keeping my example above with some modifications, this is how I was able to merge partials.
First, I simplified the placeholder in text.json to basically a unique ID, instead of trying to render the partial there.
On the hbs template that I'm rendering to, such as a page or whatever, I included the insert helper with 3 arguments. The first two are subexpressions, each return a flattened partials as strings. The key here is that subexpressions process and return a result before finishing the current process with the helper. So two flattened templates are then sent to the helper along with the placeholder to search for.
The helper uses the third argument in a regex pattern. It searches the second argument (flattened parent template) for this pattern. When found, it replaces each instance of the pattern with the first argument (yes its a global fine replace).
So, the flattened child string gets inserted into parent each time placeholder is found.
First argument
(partial "link" link.apple)
Returns
'apple'
Second argument
(partial "text" text.text-example)
Returns
'<p class="text font--variant">If you need a computer, go to {{linkToApple}}.</p>'
Third argument
'linkToApple'
text.json
{
"text-example": {
"elm": "quote",
"classes": [
"text",
"font--variant"
],
"text": "If you need a computer, go to {{linkToApple}}."
}
}
text.hbs
<{{elm}} class="{{#eachIndex classes}}{{#isnt index 0}} {{/isnt}}{{item}}{{/eachIndex}}">{{text}}</{{elm}}>
compile.hbs
{{insert (partial "link" link.apple) (partial "text" text) 'linkToApple' }}
compile.html
<p class="text font--variant">If you need a computer, go to apple.</p>
gulpfile.js
app.helper('insert', function(child, parent, name) {
const merged = parent.replace(new RegExp('\{\{(?:\\s+)?(' + name + ')(?:\\s+)?\}\}', 'g'), child);
const html = new handlebars.SafeString(merged);
return html;
});
Hope this helps someone else. I know this can use improvements, I'll try to update it when I get back to cleaning up my gulp file.