Variable replacement in file bodies

[tpluscode]

Problem to solve

I prefer to set the request body from a file to keep IDE's syntax support applicable to the given file type

Unfortunately, the {{variable}} replacement tokens do not work there

Proposal

Given that some file types may use the double brace for its own purposes, I'd suggest a new option which would opt-in to replace {{foobar}} as it would when the body was inline in a .hurl file

Request file:

POST /endpoint
file,body.json;
[Options]
replace-file-variables: true

body.json:

{
  "foo": "{{bar}}"
}

When called like hurl --variable bar=baz, it should replace the {{bar}} token in the JSON file before sending the request.

Might also consider a CLI switch --replace-file-variables

[fabricereix]

It could be indeed useful. But we must be clear whether the content is binary or text.
Currently, a template in Hurl is always text while an external file body are bytes.

[deicon]

I like the idea and started looking into it. I wonder why hurl is not using a mustache based templating system like https://github.com/nickel-org/rust-mustache.

[fabricereix]

We haven't looked specifically at this crate. We understand that using an external crate is attractive. But generally, we want to minimize external dependencies and have a good/consistent error reporting within Hurl. For the time-being, it was easier to do with internal code.

[deicon]

This sounds reasonable. So I would work on this using the existing templating as it is.
How about adding a tag in addition to file to indicate, that the file contains a template ?

POST /endpoint
file-template,body.json;application/json

{
  "foo": "{{bar}}"
}

[jcamiel]

I’m not sure we’re ready to develop the feature, I prefer we discuss the potential syntaxes before.

For instance, we plan to have support for « generator » in template:

POST https://foo.com
```
{{ now }}
```

To create a body with current time. This kind of generator could be used for providing a templatized body :

POST https://foo.com
```
{{ template data.txt }}
```

You can work on it, but not I’m not convinced by file-template syntax.

[deicon]

Looking at the generator feature, this is basically what the mustache crate brings on the table by allowing closures to be bound to the template context. Which is the reason I was asking this in the first place. If hurl would parse the inline body using the mustache template crate, the generator feature would be a matter of adding closures like

template
now
etc.

or at least this would be a start.

[fabricereix]

Discussed in #2713
reusing the file keyword with an additional template attribute

file,body.json;application/json;template=true