如何将activerecord结果转换为哈希？

Question

I have a query that returns results in ActiveRecord successfully.

select
    trunc(b.transaction_date) as transaction_date,
    sum(a.transaction_amount) as transaction_amount
from
  payment_transaction a,
  payment_settlement b
where
    a.transaction_status = 'S'
    and b.settlement_type = 'D'
    and trunc(b.transaction_date) > sysdate - 30
    and a.payment_transaction_id = b.payment_transaction_id
group by
    trunc(b.transaction_date)
order by
    trunc(b.transaction_date)

The above query returns 9 results.

What I want is to convert the entire result obtained above into a hash such as:

{
"01/01/16" => 764.00, 
"02/01/16" => 1508.00, 
"03/01/16" => 2000.00 
..
..
..
}

How can I achieve this?

Answer 1

This should work:

Hash[ActiveRecord::Base.connection.select_rows(sql)]

To explain: there is no need to instantiate AR instances here, so just run your SQL. Using select_rows will give you an array of arrays, where each element of the outer array is one row from the SQL result. Each inner array has two elements: the date and the transaction amount.

Now it just happens you can pass an array of two-element arrays to Hash[] , and it will interpret the first part of each inner array as the hash key, and the second part as the hash value.

EDIT: I'm assuming you are setting sql with something like this:

sql = <<-EOQ
    select
        trunc(b.transaction_date) as transaction_date,
        sum(a.transaction_amount) as transaction_amount
    from
      payment_transaction a,
      payment_settlement b
    where
        a.transaction_status = 'S'
        and b.settlement_type = 'D'
        and trunc(b.transaction_date) > sysdate - 30
        and a.payment_transaction_id = b.payment_transaction_id
    group by
        trunc(b.transaction_date)
    order by
        trunc(b.transaction_date)
EOQ

So that it is a string containing the SQL you'd like to run.

Answer 2

resultArray = yourQueryResult.map{|e| [e["transaction_date"], e["transaction_amount"]]}.

theHash = Hash[*resultArray.flatten]

Haven't tested :)