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Model extra attributes
In some case you may want to access a column which is not owned by the model itself. This can be provided by access
attributes hash on the model.
In this case, you should set the optional argument fetch_columns to true during the fetching:In the example below, we want to display a the identification document
type and number for each person:People.query.left_join("identification_documents"){
peoples.id == identification_documents.person_id
}.select(
"people.*",
"identification_documents.type AS doc_type",
"identification_documents.number AS doc_number"
).each(fetch_columns: true) do |x|
puts "Person #{x.full_name}: " +
"#{x.attributes["doc_type"]} - #{x.attributes["doc_number"]}"
end
The optional parameter fetch_columns is available in most of the methods where we fetch to one or multiple models.
fetch_columns reduces slightly the performance of the ORM, and that's why it's set to false by default.This can be combined also with aggregate functions access, like counter:
customers = Customer.query
.join("shippings"){ shippings.customer_id == customer.id }
.select("customers.*", "COUNT(shippings.*) as shipping_count")
customers.each(fetch_columns: true) do |x|
puts "customer #{x.id} => #{x.attributes["shipping_count"]}"
end
Last modified 4yr ago