Make JinjaRenderer work from within Air Tags

[pydanny]

Solution ideas

• Wrap the result of the JinjaRenderer
• Add a new FastAPI encoder for Jinja objs

Tasks remaining to close

• Add test
• Fix bug
• Provide documentation using JinjaRenderer within Air Tags

[pydanny]

We're running into a bit of chicken-vs-egg, in that:

1. The jinja function can't know if it is called from within a Tag or as a TemplateResponse during ASGI evaluation
2. If called within a tag it needs to return a String or SafeStr. If called as a Response it needs to return a Response.
3. Error handling this deep into things appears rigid, not something easily manoeuvred around or monkeypatched. In theory we can inspect the outer frame via the inspect module, but this is slow and problematic
4. Our planned solution is to have a string-like response that behaves like a string yet has the same attributes as a Starlette response.

[pydanny]

Gave this another go. Another problem is that the str type is quite far in design from the starlette.response.Response type. Either that or my design is off.

I could solve this with frame inspection but that's quite slow and probably brittle in a high load environment.

Quite frustrating as this is what I consider a crucial feature for the project.

What if we have the jinja callable produced by the JinjaRenderer to have a base argument so it's called like this:

import air

app = air.Air()
jinja = air.JinjaRenderer('templates')

@app.page
def index():
    return jinja(request, 'home.html', base=True,
        air.Article(
            jinja(request, 'article.html', content='TEXT HERE'
        )
    )

Alternatively or in addition to base we could have a fragment argument:

import air

app = air.Air()
jinja = air.JinjaRenderer('templates')

@app.page
def index():
    return jinja(request, 'home.html',
        air.Article(
            jinja(request, 'article.html', fragment=True, content='TEXT HERE'
        )
    )