Admin UI for shipping methods - stock locations association

[cedum]

This introduces the admin UI allowing to associate a shipping method to specific stock locations.
This makes editable also Spree::ShippingMethod#available_to_all from admin, being an attribute directly related to stock locations association behavior.

This feature is mostly used when a shipping method must be available to a specific subset of stock locations.
The shipping methods for a package are queried using the following methods:

• Spree::ShippingMethod.with_all_shipping_category_ids
• Spree::ShippingMethod.available_in_stock_location

The second query method filters the shipping methods having available_to_all enabled OR having the stock location associated.
By disabling available_to_all it becomes possible to make specific shipping methods available for specific stock locations.

Checklist:

• I have followed Pull Request guidelines
• I have added a detailed description into each commit message
• I have updated Guides and README accordingly to this change (if needed)
• I have added tests to cover this change (if needed)
• I have attached screenshots to this PR for visual changes (if needed)

[kennyadsl]

Thanks Dumi, this looks great!

[aldesantis]

@cedum thanks, this is awesome! I was wondering if we can easily clear and disable the Stock Locations field when Available to all is checked? It would be a nice UX addition.

[cedum]

I've introduced a few interactions between the checkbox and the select:

• when checking the checkbox, the selected stock locations get cleared;
• when selecting a stock location, the checkbox gets unchecked automatically;
• when clearing all stock locations, the checkbox gets checked automatically.

What do you think?

Here's a demo:

[aldesantis]

@cedum maybe it's not a good idea to auto-select the checkbox when clearing all stock locations? I'm thinking about a scenario where a store owner wants to temporarily disable a shipping method by removing it from all stock locations. They may not notice that the "Available to all stock locations" checkbox got auto-selected, and they would have the opposite result of what they were expecting. 😄

[cedum]

@cedum maybe it's not a good idea to auto-select the checkbox when clearing all stock locations? I'm thinking about a scenario where a store owner wants to temporarily disable a shipping method by removing it from all stock locations. They may not notice that the "Available to all stock locations" checkbox got auto-selected, and they would have the opposite result of what they were expecting. 😄

I think the scope of this feature is to support the main two cases UI-wise:

• adding a stock locations whitelist;
• removing the stock locations whitelist.

Actually, I'm thinking that the "Available to all" checkbox may be completely removed 😄 We can switch that attribute via a hidden input, it's mostly an implementation detail which probably should not be exposed outside.

Disabling a shipping method by removing the stock locations whitelist and disabling the checkbox IMHO is an edge-case, and I think it may be a surprise for a user. If there's a need for such a feature, we may think about introducing a dedicated and clear action for that.

What do you think? Not being a heavy Solidus admin user I may have misinterpreted something 😄

[aldesantis]

I think it makes sense — if the main use case is the whitelist, we can remove the user-facing "Available to all stock locations" input and just add a hint under the "Stock locations" input.

[cedum]

When trying to transform the "Available to all" checkbox into a hidden input
"switched" on/off via JS, I've realized it might cause inconsistencies in case of admin JS errors blocking the hidden input update, hence being difficult to debug/understand.

I took and ported @DanielePalombo suggestion from an old PR he was experimenting with. The Daniele's approach I think is better and way less confusing.

Here's a demo, hopefully, the last one 😅

[aldesantis]

Awesome @cedum, just one small nitpick on the wording for the checkbox hint!

[aldesantis]

This is amazing, thanks @cedum!