[question] Issue sith set_local_var for creating a filter in 3.0

[mardiros]

I used the (RenderContact.set_local_var)[https://docs.rs/handlebars/2.0.0/handlebars/struct.RenderContext.html#method.set_local_var] which has been drop in the 3.x version
in favor of BlockContext.

BlockContext is really a great things to scope variable properly, I have no doubt with that,
but I have created and use a lot a set filter using the register_helper.

https://github.com/mardiros/rustaman/blob/master/src/helpers/handlebars.rs#L8

My question is:

Is theres a way it did not see to keep my set helper with handlebars 3 ?

Here is my use cases:

I am maintaining a REST Client such as POSTMAN, which is not a clickodrome.
It is used to create local variables on top of every templates,
which is a very usefull feature for my project.

Actually
I use handlebars to render HTTP requests, some variables comes from the context,
but local variables are updated in the template.

Real word example:

Context

%YAML 1.2
---
token: 1a29xxxxxxxxxxxxxxxxxxxxxfb
api_graphql: https://api.github.com/graphql

Template:

# List repositories for the given username
{{ set username = "mardiros" }}

POST {{ api_graphql }}
Authorization: bearer {{ token }}
User-Agent: Rustaman
Content-Type: application/json

{
 "query": "query { repositoryOwner(login:\"{{ username }}\") { repositories(first: 100, isFork: false, privacy: PUBLIC, orderBy: { field: CREATED_AT, direction: DESC }) { edges { node { name nameWithOwner isFork }}}}}"
}

[sunng87]

Actually local var in handlebars is designed to carry some contextual data, like index in an iterator. To access local var, you will need to prefix it with @. There was an implementation issue prior to 3 that allows you to access it without @. This has been fixed in 3.0.

So you should be able to fix it by changing {{ username }} to {{ @username }}. But note that local var is only available in current scope. Helpers like each and with will create their own scopes.

But I think handlebars decorator might fit your scenario better. In handlebars-rust, decorator allows to mutate the Context within the remaining render process.

I will add an example for your case.

[sunng87]

The example: 1f78c8e

Let me know if you have any question with it.

[mardiros]

Thank you for your quick feedback.

It is actually what I was looking for. Thanks!