[feat] Name placeholder of static alias like the static alias

[fsbraun]

This issue has been raised by Tow Cowan on Slack and @petrklus:

I used static_placeholder to allow site-wide content to be edited, and could control the plugins used in this with the CMS_PLACEHOLDER_CONF setting. I’m now using v4 for a new project - am I able to do something similar with the static_alias tag? I don’t seem to be able to do so with the configuration I’ve tried.
For example, if I have the following in my base.html template (outside of any blocks):

{% static_alias 'banner' %}

And then the following in my settings:

CMS_PLACEHOLDER_CONF = {
	"banner": {
		"plugins": ["BannerPlugin"],
	},
}

When I view the Alias (Django Admin -> Django CMS Alias -> Aliases -> Preview) and then try to add a plugin, it ignores the above placeholder config. If I add a key for a “content” placeholder in CMS_PLACEHOLDER_CONF it does allow me to configure the available plugins, but this would mean that all of my static_alias tags would have the same configuration.

[aacimov]

Also, when using the template system it would be very helpful to have the ability to contextually show different markup regarding the static_alias, as with static_placeholders in v3, e.g:

{% if static_alias_name == 'Static Alias 1' %}
    <div class="static_alias_1_wrap"></div>
{% elif static_alias_name == 'Static Alias 2' %}
    <div class="static_alias_2_wrap"></div>
{% else %}
    <div class="static_alias_default_wrap"></div>
{% endif %}

[aacimov]

Hey @evill33t actually I did exactly the same to achieve the wanted behaviour but dealing with clients is the main cause I asked for the "old fashion" behaviour since they usually expect something to be added and just work OOTB (without selecting the actual template).

Thanks for the heads-up though.

[evill33t]

I deleted my comment, I was wrong about the template - imho it should be able to choose different slots which would solve this issue.

[fsbraun]

There's a basic design problem here:

• All aliases share a template (you can change templates for alias plugins, the render_alias tag within them calls the same common alias template, again.)
• The way django CMS 4 core identifies the templates in a frontend-editable model is static (same template -> same placeholder names - always)

My best assessment is that one could:

• Extend the core's way of identifying placeholder slots in frontend-editable models, and
• Let the placeholder be called like the static_code or "content" if static_code is unset. (This is a breaking change, however, since the placeholder names of existing aliases changes, partly mitigable by a custom migration)