Better error when submitting order with out of stock product #390
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| def initialize(id) | ||
| @id = id | ||
| end | ||
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| def set_customer(customer_id) | ||
| raise CustomerAlreadyAssigned if @customer_id | ||
| return if @customer_id == customer_id |
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I think we need to allow users to reassign customers. If order submission fails the first time the user is still being assigned. So when user tries again this raises an exception and brakes the process.
I changed it so when customer_id is not changed it does nothing, but if it is changed then we emit the event.
marlena-b
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| state.order_lines.each do |product_id, quantity| | ||
| command_bus.(Inventory::Reserve.new(product_id: product_id, quantity: quantity)) | ||
| state.product_reserved(product_id) | ||
| rescue Inventory::InventoryEntry::InventoryNotAvailable | ||
| unavailable_products << product_id | ||
| end |
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ReservationProcess no longer stops at the first unavailable product. Instead, it tries to reserve all of them and records which were unavailable. This way we can later display the full list of unavailable products.
| end | ||
| event_store.publish(event, stream_name: stream_name(state.order_id)) |
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ReservationProcess now emits events. We then subscribe to these events in the controller and display proper errors to the user.
We could raise an error instead but then the transaction would be rolled back and most of the code here would make no sense.
| def order_side_effects(state) | ||
| event_store | ||
| .within { yield } | ||
| .subscribe(to: ReservationProcessFailed) { reject_order(state) } | ||
| .subscribe(to: ReservationProcessSuceeded) { accept_order(state) } | ||
| .call |
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I think these side effects could be extracted to fully-fledged event handlers. Then the ReservationProcess could have only a single responsibility. This PR is already big so I didn't want to extract it here. Let me know what you think and I will add an issue for this refactor.
| ActiveRecord::Base.transaction do | ||
| command_bus.(Ordering::SubmitOrder.new(order_id: params[:order_id])) | ||
| command_bus.(Crm::AssignCustomerToOrder.new(customer_id: cookies[:client_id], order_id: params[:order_id])) | ||
| Orders::SubmitService.new(order_id: params[:order_id], customer_id: cookies[:client_id]).call.then do |result| |
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The code in this controller got more and more complex so I extracted it to a service.
I used a very simple Service object implementation combined with a simple but flexible Result object. This results in an expressive DSL like the one below :)
(the DSL was partly inspired by respond_to method)
| redirect_to edit_order_path(params[:order_id]), alert: "You can't submit an empty order" | ||
| rescue Crm::Customer::NotExists | ||
| redirect_to order_path(params[:order_id]), alert: "Order can not be submitted! Customer does not exist." | ||
| Orders::SubmitService.new(order_id: params[:order_id], customer_id: params[:customer_id]).call.then do |result| |
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I initially wanted to have two separate services for the admin and client side but then they looked almost entirely the same. So I decided to merge them so we don't duplicate too much code and tests.
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| class ApplicationService | |||
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This is the first time service objects are used in this repo so I wanted to keep them as simple as possible. In my implementation service objects should only implement initialize and call methods and then we can call them like MyService.call(..). This makes it easier to mock them (bc we only need to mock the class method call).
Please let me know if you prefer to use some other implementation instead, this is just my proposal.
| if success | ||
| Result.new(:success) | ||
| else | ||
| Result.new(:products_out_of_stock, unavailable_products) | ||
| end | ||
| rescue Ordering::Order::IsEmpty | ||
| Result.new(:order_is_empty) | ||
| rescue Crm::Customer::NotExists | ||
| Result.new(:customer_not_exists) |
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call method returns a Result object which represents a logical path of execution combined with optional arguments (e.g. unavailable_products).
| def path(name, &block) | ||
| return unless @status == name.to_sym | ||
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| block.call(*@args) | ||
| end |
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There is also an alternative implementation which uses more metaprogramming but results in a nicer DSL:
def method_missing(name, *_, &block)
return unless @status == name.to_sym
block.call(*@args)
end
and then the DSL looks like this:
MyService.call(params).then do |on|
on.success { puts "Awesome!" }
on.validation_failed { |errors| puts "Oh no, there are some errors: #{errors}" }
on.something_else { |arg1, arg2| puts arg1 * arg2 }
end
Let me know which one you prefer :)
marlena-b
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There are many changes in this pull request which I would like to debate separately, but as a whole I think it's ready to be merged.
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Issue: #375
Before when a product was added to an order and subsequently went out of stock before submission, the system incorrectly showed a success message "Your order is being submitted" while leaving the order in draft status. Now it shows "Order can not be submitted! Product not available in requested quantity!".
There are a lot of changes. I will try to explain all of them in the comments below.
The implementation for the Result object was taken from this presentation: https://www.icloud.com/keynote/0x2bfAdGek3Eg-I_2kIomD-6g#Controller_refactoring (it lacks notes but you can check slides 7 and 17 for "before" and "after")