defmodule YourModel do

  # specify the DynamoDB key column (default is :hash). 
  use DDBModel :id

  # if you have a table with hash key and range, pass a tuple
  use DDBModel {:id, :timestamp}

  # optionally set a custom table name. default is the model name
  use DDBModel table_name: "your_dynamo_table"

end

defmodule Account do

  use DDBModel 
  # uuid type automatically creates a uuid before saving if needed
  defcolumn :uuid, type: :uuid

  # set default value
  defcolumn :status, default: :A

  # validate in_list
  defcolumn :membership, default: :free, in_list: [:free, :paid]

  # validate not null
  defcolumn :first_name, null: false

  # validate by function
  defcolumn :last_name, validate: &1 != "Doe"
  # or defcolumn :last_name, validate: fn(v) v != "Doe" end

end

  # Create an instance with new
  account = Account.new

  # Pass in parameters by keyword
  account = Account.new first_name: "Dale", last_name: "Cooper"

  # Update a single parameter (don't forget to assign to a variable, the update does not happen in place..)
  account = account.membership(:paid)

  # Mass Assignment
  account = account.set membership: :paid, status: :A

  # Whitelisted mass assignment
  # change only membership and status
  fields = [:membership, :status]
  account = account.set [membership: :paid, password: "owned", first_name: "John"], fields

  # create or update with put!
  {:ok, account} = account.put!

  # pass an array for batch put
  {:ok, accounts} = Account.put! [Account.new, Account.new]

  # ensure that the record is new, i.e. nothing gets overwritten in the DB
  {:ok, account} = Account.new.insert!

  # ensure the record exist
  {:ok, account} = account.membership(:paid).update!

  # delete an existing record
  {:ok, id} = account.delete!

  # delete works with IDs, too
  {:ok, id} = Account.delete! {22,4}

  # batch delete records
  {:ok, ids} = Account.delete [acc1, acc2, acc3]

  # find by id
  {:ok, account} = account.find("1234")

  # find returns :not_found when the account does not exist
  :not_found = account.find("non-existent")

  # pass a list for batch find
  {:ok, [acc1, acc2]} = account.find ["1234", "1235"]