kura_type behaviour (kura v2.0.6)

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Behaviour for user-defined types.

Implement this behaviour to create custom types that integrate with Kura's cast/dump/load pipeline.

Example: Money type (integer cents)

-module(money_type).
-behaviour(kura_type).
-export([cast/1, dump/1, load/1, pg_type/0]).

pg_type() -> ~"INTEGER".

cast({dollars, D}) when is_number(D) -> {ok, round(D * 100)};
cast(V) when is_integer(V)          -> {ok, V};
cast(_)                              -> {error, ~"expected integer cents or {dollars, N}"}.

dump(V) when is_integer(V) -> {ok, V};
dump(_)                    -> {error, ~"expected integer"}.

load(V) when is_integer(V) -> {ok, V};
load(_)                    -> {error, ~"unexpected value"}.

Then use in your schema:

fields() ->
    [#kura_field{name = price, type = {custom, money_type}}].

Summary

Callbacks

cast/1

Cast an external value to the internal representation.

dump/1

Convert the internal value to a format suitable for PostgreSQL.

load/1

Convert a PostgreSQL value back to the internal representation.

pg_type()

Return the PostgreSQL DDL type string (e.g. ~"INTEGER", ~"TEXT").

Callbacks

cast/1

-callback cast(term()) -> {ok, term()} | {error, binary()}.

Cast an external value to the internal representation.

dump/1

-callback dump(term()) -> {ok, term()} | {error, binary()}.

Convert the internal value to a format suitable for PostgreSQL.

load/1

-callback load(term()) -> {ok, term()} | {error, binary()}.

Convert a PostgreSQL value back to the internal representation.

pg_type()

-callback pg_type() -> binary().

Return the PostgreSQL DDL type string (e.g. ~"INTEGER", ~"TEXT").