[RFC] Sorting warehouses within channel

[IKarbowiak]

The goal is to allow staff users to set the warehouse order of stock allocation and reservation. The warehouse order will be configurable per channel

General assumptions

• Staff users with MANAGE_CHANNELS permission should be able to sort the warehouses within the channel.
• Newly added warehouses will be added to the end of the sort order.
• The channel will have a configurable option to choose the default strategy for allocation. The options will be:
  • follow the warehouse order
  • prioritize the stocks with the highest available quantities- it will minimalize the number of allocations by firstly allocating in the warehouses with the highest quantity available value
• Defining the allocation settings during the channel creation will be not required. When no provided the option PRIORITIZE_SORTING_ORDER will be set.
• The default allocation strategy for exisitng channels will be PRIORITIZE_HIGH_STOCK.

Allocation and reservations

• Depend on the channel settings reservations and allocations:
  • will happen with respect to the sort of warehouse order (PRIORITIZE_SORTING_ORDER strategy)
  • will firstly happen in the stocks with the highest available quantity value (PRIORITIZE_HIGH_STOCK strategy)
• For checkout with the collection point chosen as a delivery method, the chosen collection point will be used as the first choice.

The example of stocks and allocations for:

• PRIORITIZE_SORTING_ORDER strategy
  
• PRIORITIZE_HIGH_STOCK strategy
  

Database changes

• Rewrite the Channel - Warehouse intermediate model. Extend it with the sort_order field.
  Tips:

  • https://docs.djangoproject.com/en/4.0/howto/writing-migrations/#changing-a-manytomanyfield-to-use-a-through-model
  • https://medium.com/@NyanKiyoshi/how-to-migrate-a-through-to-a-many-to-many-relation-in-django-d09d8bc2c67

• Extend the Channel model with allocation_strategy: CharField field with the choices: follow_the_warehouse_order, prioritize_high_stock.

API changes

Introduce StockSettings type.

type StockSettings {
  allocationStrategy: allocationStrategyEnum!
}

enum allocationStrategyEnum {
  PRIORITIZE_SORTING_ORDER
  PRIORITIZE_HIGH_STOCK
}

Extend the channel type with allocationSettings field. Allow defining the allocationSettings in the channelCreate and channelUpdate mutations.

type Channel implements Node {
  ...
  stockSettings: StockSettings
}

input ChannelCreateInput {
  ...
  stockSettings: StockSettingsInput
}

input ChannelUpdateInput{
  ...
  stockSettings: StockSettingsInput
}

input StockSettingsInput {
  allocationStrategy: allocationStrategyEnum!
}

Add a channelReorderWarehouses mutation for sorting the warehouses assigned to the channel.

type Mutation {
  ...
  channelReorderWarehouses(
    channelId: ID!, moves: [ReorderInput!]!
  ): channelReorderWarehouses
}


input ReorderInput {
  id: ID!
  sortOrder: Int
}


type channelReorderWarehouses{
  channel: Channel
  errors: [ChannelError!]!
}

Internal task: SALEOR-7914

Impact

• New migrations
• New/Updated API fields or mutations
• Deprecated API fields or mutations
• Removed API types, fields, or mutations
• Documentation needs to be updated

Pull Request Checklist

• Privileged queries and mutations are guarded by proper permission checks
• Database queries are optimized and the number of queries is constant
• Database migration files are up to date
• The changes are tested
• GraphQL schema and type definitions are up to date
• Changes are mentioned in the changelog

[patrys]

Task linked: SALEOR-7914 Allow warehouses to be sorted within a shipping zone