Ngx-formly: expressionProperties callback function doesn't seem to subscribe to observables

[juristr]

Description

I didn't yet look into the implementation, but from a usage perspective it looks like the callback functions in the expression properties don't subscribe to observables. Not sure whether this is intended.

I tried this example https://formly.dev/examples/advanced/i18n but changed it slightly to not use

expressionProperties: {
   'templateOptions.label': this.translate.stream('HOME.SELECT'),
},

but rather

expressionProperties: {
   'templateOptions.label': () => this.translate.stream('HOME.SELECT'),
},

The goal being to be able to access information from the passed params of the callback function such as the field configuration.

Minimal Reproduction

https://stackblitz.com/edit/angular-dqx3uc?file=src/app/app.component.ts
https://stackblitz.com/...

[aitboudad]

not supported yet(related to https://github.com/ngx-formly/ngx-formly/issues/1818), as an alternative, you may use:

• https://github.com/ngx-formly/ngx-formly/issues/1818#issuecomment-541207382.
• or https://formly.dev/examples/advanced/i18n-alternative

[juristr]

@aitboudad alright, I assumed this might be the case. Yes I'm actually using the extension way of embedding ngx-translate 😃. _(Hint: recording the egghead course. 15 lessons recorded, 2 more to go. Will probably publish on Monday 🎉. Let's spread the ngx-formly awesomeness)_

Closing this issue for now then

[aitboudad]

Wow, awesome, I can't beat you on that part 😄💪.
Once ready you may add it to our doc as an official video course of formly (main menu or the home page as you prefer).