Can't swap Primary Position with Flex without an open Flex Position

[axelclark]

Can't swap Primary Position with Flex without an open Flex Position

For example, can't swap Kentucky from CBB to Flex1 and North Carolina from Flex1 to CBB

[axelclark]

Possible fixes:

1. Allow owner to move player into "Unassigned" position
   -- Unassigned == 0 points to motivate owners to move to a position
2. Identify a "swap" transaction and have the software break the transaction into 2 moves
   -- Primary to "Unassigned"
   -- From Flex1 to CBB & from "unassigned to Flex1

[axelclark]

Maybe need to modify cast_assoc(:roster_positions)

ex338/lib/ex338/fantasy_team.ex

Lines 105 to 112 in 906dbc7

	def owner_changeset(struct, params \\ %{}) do
	struct
	|> cast(params, [:team_name, :autodraft_setting])
	|> validate_required([:team_name])
	|> cast_assoc(:roster_positions)
	|> cast_assoc(:draft_queues)
	|> validate_length(:team_name, max: 16)
	end

Maybe add a test here

ex338/test/ex338/fantasy_team/store_test.exs

Lines 523 to 540 in 906dbc7

	describe "update_team/2" do
	test "updates a fantasy team and its roster positions" do
	league = insert(:fantasy_league)
	team = insert(:fantasy_team, team_name: "Brown", fantasy_league: league)
	position = insert(:roster_position, fantasy_team: team)
	team = Store.find_for_edit(team.id)
	attrs = %{
	"team_name" => "Cubs",
	"roster_positions" => %{"0" => %{"id" => position.id, "position" => "Flex1"}}
	}
	{:ok, team} = Store.update_team(team, attrs)
	assert team.team_name == "Cubs"
	assert Enum.map(team.roster_positions, & &1.position) == ~w(Flex1)
	end
	end

[axelclark]

System should do this automatically...

[axelclark]

https://www.postgresql.org/docs/current/sql-createtable.html

DEFERRABLE
NOT DEFERRABLE
This controls whether the constraint can be deferred. A constraint that is not deferrable will be checked immediately after every command. Checking of constraints that are deferrable can be postponed until the end of the transaction (using the SET CONSTRAINTS command). NOT DEFERRABLE is the default. Currently, only UNIQUE, PRIMARY KEY, EXCLUDE, and REFERENCES (foreign key) constraints accept this clause. NOT NULL and CHECK constraints are not deferrable. Note that deferrable constraints cannot be used as conflict arbitrators in an INSERT statement that includes an ON CONFLICT DO UPDATE clause.

INITIALLY IMMEDIATE
INITIALLY DEFERRED
If a constraint is deferrable, this clause specifies the default time to check the constraint. If the constraint is INITIALLY IMMEDIATE, it is checked after each statement. This is the default. If the constraint is INITIALLY DEFERRED, it is checked only at the end of the transaction. The constraint check time can be altered with the SET CONSTRAINTS command.

[axelclark]

https://elixirforum.com/t/repo-update-all-on-a-column-with-a-unique-constraint/31960/3

https://hashrocket.com/blog/posts/deferring-database-constraints

[axelclark]

https://github.com/axelclark/ex338/blob/master/priv/repo/migrations/20161010221818_add_constraints_to_roster_position.exs