Dynamic variables in key names

[rkaw92]

This change adds support for resolving key names in objects using variables. For example, if the data passed to carbone.render contains:

{
  "language": "de",
  "item": {
    "names": { "en": "Washing machine", de: "Waschmaschine" }
  }
}

Then, in the template, we can use a key from item.names that depends on the passed language by using a Carbone variable (also called "alias" in the Designer documentation) with a new de-referencing syntax:

{#lang = d.language}
{d.item.names.$$lang}

Under the hood, this key reference translated to an IIFE that evaluates _root.d.language or returns an empty string on error (like when some object along the path is null/undefined).

Only references to known variables are replaced with dynamically-computed keys, so this change preserves compatibility for users of key names with $$ in them (they work as usual) - unless you define a variable of the same name.

Square brackets were considered to give developers more familiarity (would have been similar to obj[variable] in JS), but ultimately a "$$" syntax was chosen that requires minimal changes to the parser/renderer logic.

Note that this function only supports plain, parameter-less aliases/variables so far (no array filters), and the variable code (the part after =) must be eval-able.

Basic tests for this renderer feature are provided.

[dcdamien]

@dgrelaud is there anything that should be done to merge this change?

[dgrelaud]

is there anything that should be done to merge this change?

Yes, this our top priority next feature.
I think it will be available at the end of december (with other great features! )

The solution provided by rkaw92 is great but it does not work in all cases with nested arrays for example.

Stay tuned!

[dgrelaud]

The new v2.0 includes this feature now.
Thank you for your help.

[Alexanderdunlop]

Does this work on an array.
For example:

{#lang = d.language}
{d.items[i].$$lang}

I am trying this and everything is rendering apart from {d.E.1[i].$$customer}