Accessing the values from the resultset in ecto

Questions / Help
1

Sorry for the stupid question. :grinning:

My result set looks like this

{%Epos.Sales.Transaction{
   __meta__: #Ecto.Schema.Metadata<:loaded, "transactions">,
   amount_paid: 0.0,
   bill_amount: 0.0,
   comments: nil,
   created_by: "shan",
   customer_id: "shan",
   customers: #Ecto.Association.NotLoaded<association :customers is not loaded>,
   discount_on_items: 0.0,
   discount_on_total: 0.0,
   inserted_at: #DateTime<2019-01-30 08:46:21Z>,
   is_active: true,
   net_amount: 0.0,
   sale_date: #DateTime<2019-01-30 08:46:21Z>,
   sales_type: "COUNTER_SALE",
   tax: 0.0,
   tax_percentage: "0%",
   transaction_status: "PENDING",
   transactions_id: 1548837981076,
   updated_at: #DateTime<2019-01-30 08:46:21Z>,
   updated_by: "shan"
 },
 %Epos.Sales.TransactionDetail{
   __meta__: #Ecto.Schema.Metadata<:loaded, "transaction_details">,
   cost_price: 100.0,
   created_by: "shan",
   discount: 4.4,
   inserted_at: #DateTime<2019-01-30 08:46:32Z>,
   price: 1306.0,
   product_id: "A3",
   qty: 10,
   selling_price: 135.0,
   transaction_details_id: 1548837981076,
   transactions: #Ecto.Association.NotLoaded<association :transactions is not loaded>,
   updated_at: #DateTime<2019-01-30 08:46:40Z>,
   updated_by: "shan"
 }}

Please guide me how to access the values from this?

2

Do you know what is the data type returned? What have you tried so far? Which errors did you get?

3

The result type is a List I extracted like this

[head | _tail] = res

Here res is the List which comes as a result from Ecto query.

Query looks like this,

from(t in Transaction,
      join: td in TransactionDetail,
      where: td.transaction_details_id == t.transactions_id and t.transactions_id == ^id,
      lock: "FOR UPDATE",
      select: {t, td}
    )
    |> Repo.all()
    |> case do
      [] ->
        Repo.rollback("Invalid checkout.")

      res ->
        {:ok, res}
    end

The value that i put in the post is the value which comes from the head

I tried accessing like head.customer_id, head.transactions.customer_id.

4

Great! In your select, you are returning a tuple:

select: {t, td}

This means you first need to extract entries from the tuple before you access the fields. So for example, after you get the head:

{t, td} = head
t.customer_id

What do you think?

2 Likes
5

Yeah that’s right. I missed that totally. I printed the head in console and based on that I tried things.

Thank you!

1 Like