109 lines
2.4 KiB
Elixir
109 lines
2.4 KiB
Elixir
defmodule ISN do
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@behaviour Postgrex.Extension
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@isn ~w(ean13 isbn13 ismn13 issn13 isbn ismn issn upc)
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@moduledoc """
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A Postgrex.Extension enabling the use of postgresql data types from the isn
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extension.
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In lib/ directory create a file with the following content:
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Postgrex.Types.define(
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MyApp.PostgrexTypes,
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[ISN] ++ Ecto.Adapters.Postgres.extensions(),
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json: Poison
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)
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Add the following lines in conig.exs:
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config :my_app, MyApp.Repo,
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types: MyApp.PostgrexTypes
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Then you can do Ecto.Migrations like this:
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defmodule MyApp.Repo.Migrations.CreateBook do
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use Ecto.Migration
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def change do
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create table(:books) do
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add :isbn, :isbn13
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# other fields
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end
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end
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end
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You can also define Ecto.Models using the matching custom Ecto.Types:
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defmodule MyApp.Book do
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use MyApp.Web, :model
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schema "books" do
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field :isbn, ISN.ISBN13, read_after_writes: true
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# other fields
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end
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end
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"""
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def init(opts), do: Keyword.get(opts, :decode_copy, :reference)
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def matching(_), do: Enum.zip(Stream.cycle([:type]), @isn)
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def format(_), do: :text
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def encode(_opts) do
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quote do
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thing ->
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[<<IO.iodata_length(thing)::int32>> | thing]
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end
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end
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def decode(:copy) do
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quote do
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<<len::int32, thing::binary-size(len)>> ->
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:binary.copy(thing)
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end
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end
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def decode(:reference) do
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quote do
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<<len::int32, thing::binary-size(len)>> ->
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thing
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end
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end
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end
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# Generate Ecto.Type modules for all supported data types in the `isn`
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# postgresql module.
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for module <- ~w(ISBN ISMN ISSN ISBN13 ISMN13 ISSN13 UPC EAN13) do
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module_name = Module.concat([ISN, module])
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ecto_type = module |> String.downcase() |> String.to_atom()
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defmodule module_name do
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@behaviour Ecto.Type
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@moduledoc """
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Definition for the ISN.#{module} module.
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How to use this in an Ecto.Model
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defmodule MyApp.Book do
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use MyApp.Web, :model
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schema "books" do
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field :#{ecto_type}, ISN.#{module}
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# other fields
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end
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end
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"""
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def type, do: unquote(ecto_type)
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def cast(nil), do: :error
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def cast(isn), do: {:ok, to_string(isn)}
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def load(isn), do: {:ok, to_string(isn)}
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def dump(isn), do: {:ok, to_string(isn)}
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end
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end
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