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elixirphoenix-frameworkecto

How to aggregate in preload

So I have 3 tables borrower, avatar and loan

Borrower -> has_one avatar

Borrower -> has_many loan

Loan Controller

def list_borrowers do

query =
  from(
    p in Borrower,
    select: p,
    preload: [:avatar],
    preload: [:loan] # I WANT TO AGGREGATE THIS USING COUNT
  )

IO.inspect(Repo.all(query))end

This is working properly my problem is I don't know how to aggregate the loan.

I just want to know the number of all the loans of that borrower.

Solution

  • I am unaware of any possible way to preload the aggregate, but you might declare virtual field instead and include it into your query as:

    from p in Borrower,
  join: l in Loan,
  on: p.id == l.borrower_id,
  select: %{p | loan_count: count(l.id)}, # virtual field
  preload: [:avatar]