How to best integrate an external API?

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1

I have an api to a logistics system where customers of the transport company can create a quote for delivery of goods.
I will develop a web app, where the quote will start as a quote request saved in a postgres database. A UI function will allow submitting this request to multiple logistics systems to compare pricing. When the customer wants to create a quote they will submit to create a quote, which will return a quote number from the api if successful.

The quote has a From and To delivery address and quote items showing the quantity, description and dimensions for multiple products.

My questions:

  1. Is it recommended to model quote items as a resource and embed as a resource attribute of the quote resource ?
  2. As for the form, how does ash support managing these items in the UI?
  3. To make this a multitenant application, how can the logistics tenants manage their system api and credentials and their own auth policy?
2

You can write an update or a generic action that will communicate with an external API using essentially regular Elixir code. You can definitely model the quote items as an embedded resource to store the results of those calls in the attributes etc.

You can do something like:

update :get_quote do
  change fn changeset, _ -> 
    Ash.Changeset.before_transaction(changeset, fn changeset -> 
      # make an external call and save the results in the changeset here.
    end)
  end
end

or you could use a generic action

# perhaps you return the quote number. You can return whatever type you want here.
action :get_quote, :struct do
  constraints instance_of: Quote
  argument :quote_request_id, :uuid

  run fn input, _context -> 
    # lookup the quote
    # make an external call
    # update the quote
    # return {:ok, quote}
  end
end
1 Like
3

AshPhoenix.Form supports managing nested forms/related data, and you can lookup the credentials for the organization/tenant before making your request.