schematic is a library for data specification, validation, and transformation.
schematic works by constructing schematics that specify your data and can then unify to them from external data and dump your internal data back to the external data.
There are 12 builtin schematics that you can use to build new schematics that fit your own domain model.
bool/0str/0int/0float/0list/1tuple/1map/1schema/2raw/2any/0all/1oneof/1
Literals can be used as schematics and are unified with == semantics.
Struct literals can be used as schematics, and the input is unified by seeing if it is an instance of the given struct.
Let's take a look at an example schematic for a JSON-RPC request for a bookstore API.
defmodule Bookstore do
defmodule Datetime do
import Schematic
def schematic() do
raw(
fn
i, :to -> is_binary(i) and match?({:ok, _, _}, DateTime.from_iso8601(i))
i, :from -> match?(%DateTime{}, i)
end,
transform: fn
i, :to ->
{:ok, dt, _} = DateTime.from_iso8601(i)
dt
i, :from ->
DateTime.to_iso8601(i)
end
)
end
end
defmodule Author do
import Schematic
defstruct [:name]
def schematic() do
schema(__MODULE__, %{
name: str()
})
end
end
defmodule Book do
import Schematic
defstruct [:title, :authors, :publication_date]
def schematic() do
schema(__MODULE__, %{
{"publicationDate", :publication_date} => Bookstore.Datetime.schematic(),
title: str(),
authors: list(Bookstore.Author.schematic())
})
end
end
defmodule BooksListResult do
import Schematic
defstruct [:books]
def schematic() do
schema(__MODULE__, %{
books: list(Bookstore.Book.schematic())
})
end
end
defmodule BooksListParams do
import Schematic
defstruct [:query, :order]
def schematic() do
schema(__MODULE__, %{
query:
nullable(
map(%{
{"field", :field} =>
oneof(["title", "authors", "publication_date"]),
{"value", :value} => str()
})
),
order: nullable(oneof(["asc", "desc"]))
})
end
end
defmodule BooksList do
import Schematic
defstruct [:id, :method, :params]
def schematic() do
schema(__MODULE__, %{
id: int(),
method: "books/list",
params: Bookstore.BooksListParams.schematic()
})
end
end
endReading external data into your data model.
iex> alias SchematicTest.Bookstore
iex> import Schematic
iex> unify(Bookstore.BooksList.schematic(), %{
...> "id" => 99,
...> "method" => "books/list",
...> "params" => %{
...> "query" => %{
...> "field" => "authors",
...> "value" => "Michael Crichton"
...> },
...> "order" => "desc"
...> }
...> })
{:ok,
%Bookstore.BooksList{
id: 99,
method: "books/list",
params: %Bookstore.BooksListParams{
query: %{field: "authors", value: "Michael Crichton"},
order: "desc"
}
}}Dumping your internal data model.
iex> alias SchematicTest.Bookstore
iex> import Schematic
iex> dump(Bookstore.BooksListResult.schematic(), %Bookstore.BooksListResult{
...> books: [
...> %Bookstore.Book{
...> title: "Jurassic Park",
...> authors: [%Bookstore.Author{name: "Michael Crichton"}],
...> publication_date: ~U[1990-11-20 00:00:00.000000Z]
...> },
...> %Bookstore.Book{
...> title: "The Lost World",
...> authors: [%Bookstore.Author{name: "Michael Crichton"}],
...> publication_date: ~U[1995-09-08 00:00:00.000000Z]
...> }
...> ]
...> })
{:ok,
%{
"books" => [
%{
"authors" => [%{"name" => "Michael Crichton"}],
"publicationDate" => "1990-11-20T00:00:00.000000Z",
"title" => "Jurassic Park"
},
%{
"authors" => [%{"name" => "Michael Crichton"}],
"publicationDate" => "1995-09-08T00:00:00.000000Z",
"title" => "The Lost World"
}
]
}}schematic fires the following events:
[:schematic, :unify, :start]- Fired when unification starts.[:schematic, :unify, :stop]- Fired when unification stops.[:schematic, :unify, :exception]- Fired when unification raises an exception.
def deps do
[
{:schematic, "~> 0.1"}
]
endDocumentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/schematic.
The MIT License (MIT)
Copyright © 2023 Mitchell A. Hanberg
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The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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