estructura

# Estructura    [![Kantox ❤ OSS](https://img.shields.io/badge/❤-kantox_oss-informational.svg)](https://kantox.com/)  [![Test](https://github.com/am-kantox/estructura/workflows/Test/badge.svg)](https://github.com/am-kantox/estructura/actions?query=workflow%3ATest)  [![Dialyzer](https://github.com/am-kantox/estructura/workflows/Dialyzer/badge.svg)](https://github.com/am-kantox/estructura/actions?query=workflow%3ADialyzer)

**Extensions for _Elixir_ structures.**

## Installation

```elixir
def deps do
  [
    {:estructura, "~> 0.1"},
    # optionally you might want to add `boundary` library 
    # it is used by `estructura` and many other projects
    # more info: https://hexdocs.pm/boundary
    {:boundary, "~> 0.9", runtime: false}
  ]
end
```
I suggest adding [`boundary`](https://hexdocs.pm/boundary) as a dependency since that is used in this project.

## Features

### Nested Structures

`Estructura.Nested` provides powerful nested structure support with validation, coercion, and generation capabilities:

```elixir
defmodule User do
  use Estructura.Nested

  defstruct [
    name: "",
    address: %{
      city: "",
      street: %{name: "", house: 0}
    }
  ]

  # Validation rules
  def validate(:name, value), do: String.length(value) > 0
  def validate("address.street.house", value), do: value > 0
end

# Usage
iex> user = %User{name: "John", address: %{city: "London", street: %{name: "High St", house: 42}}}
iex> User.validate(user)
{:ok, %User{...}}
```

### Type System

Estructura provides a rich type system with built-in types and scaffolds for custom types:

#### Built-in Types

- `DateTime` - For handling datetime values
- `Date` - For date values
- `Time` - For time values
- `URI` - For URI handling
- `IP` - For IPv4 and IPv6 addresses
- `String` - For string values

```elixir
defmodule Event do
  use Estructura.Nested

  defstruct [
    timestamp: nil,
    url: nil
  ]

  def type(:timestamp), do: Estructura.Nested.Type.DateTime
  def type(:url), do: Estructura.Nested.Type.URI
end
```

#### Type Scaffolds

##### Enum Types

Create types with predefined values:

```elixir
defmodule Status do
  use Estructura.Nested.Type.Enum,
    elements: [:pending, :active, :completed]
end

iex> Status.validate(:pending)
{:ok, :pending}
iex> Status.validate(:invalid)
{:error, "Expected :invalid to be one of: [:pending, :active, :completed]"}
```

##### Tag Sets

Manage lists of predefined tags:

```elixir
defmodule Categories do
  use Estructura.Nested.Type.Tags,
    elements: [:tech, :art, :science]
end

iex> Categories.validate([:tech, :art])
{:ok, [:tech, :art]}
iex> Categories.validate([:invalid])
{:error, "All tags are expected to be one of [:tech, :art, :science]..."}
```

### Coercion and Validation

Estructura provides flexible coercion and validation:

```elixir
defmodule Temperature do
  use Estructura.Nested

  defstruct value: 0, unit: :celsius

  def coerce(:value, str) when is_binary(str) do
    case Float.parse(str) do
      {num, ""} -> {:ok, num}
      _ -> {:error, "Invalid number"}
    end
  end

  def validate(:value, v), do: v >= -273.15  # Absolute zero
  def validate(:unit, u), do: u in [:celsius, :fahrenheit, :kelvin]
end
```

### Lazy Values

Use `Estructura.Lazy` for deferred computation:

```elixir
defmodule Cache do
  use Estructura.Nested

  defstruct value: Estructura.Lazy.new(&expensive_computation/1)

  def expensive_computation(_), do: :timer.sleep(1000) && :computed
end
```

### Flattening and Transformation

Convert nested structures to flat representations:

```elixir
defmodule User do
  use Estructura.Nested, flattenable: true

  defstruct name: "", address: %{city: "", postal_code: ""}
end

iex> user = %User{name: "John", address: %{city: "London", postal_code: "SW1"}}
iex> Estructura.Flattenable.flatten(user)
%{"name" => "John", "address_city" => "London", "address_postal_code" => "SW1"}
```

## Property Testing

Estructura supports property-based testing out of the box:

```elixir
defmodule UserTest do
  use ExUnit.Case
  use ExUnitProperties

  property "valid users are validated" do
    check all %User{} = user <- User.__generator__() do
      assert {:ok, ^user} = User.validate(user)
    end
  end
end
```

## Changelog
* `1.8.0` — `validate/1`
* `1.7.0` — better infrastructure for `Types`, `URI`, `IP`, `Scaffold`
* `1.6.0` — `jsonify: true | module()` option in a call to `Estructura.Flattenable.flatten/2`
* `1.5.0` — no `:formulae` dependency
* `1.4.1` — allow functions of arity 1 in `content` as coercers in a call to `Estructura.Aston.coerce/2`
* `1.4.0` — allow coercers in a call to `Estructura.Aston.coerce/2`
* `1.3.0` — calculated fields for `Estructura` and `Estructura.Nested`
* `1.2.12` — export type from `Estructura.Nested`
* `1.2.11` — nullable coercers
* `1.2.10` — coercers for floats, and date/time values
* `1.2.8` — `Estructura.Tree` → `Estructura.Aston` + `Aston.access/2` to retrieve and access key by names
* `1.2.5` — `use Estructura.Nested flattenable: boolean(), jason: boolean(), transformer: boolean()`
* `1.2.3` — Several `coerce/1` and `validate/1` clauses, default coercers
* `1.2.2` — `Estructura.Flattenable`
* `1.2.1` — Generators for `:datetime` and `:date`
* `1.2.0` — `Estructura.Nested` would attempt to split keys by a delimiter if instructed
* `1.1.0` — `Estructura.Aston` to hold an AST structure, like XML
* `1.0.0` — Elixir v1.16 and deps
* `0.6.0` — `Estructura.Transform` to produce squeezed representations of nested structs
* `0.5.5` — export declarations of both `Estructura` and `Estructura.Nested` to docs
* `0.5.4` — `Estructura.Nested` allows `cast/1` to cast nested structs from maps
* `0.5.3` — `Estructura.diff/3` now understands maps
* `0.5.2` — `Estructura.diff/3`
* `0.5.1` — [BUG] Fixed `Collectable` and `Enumerable` injected implementations
* `0.5.0` — `Estructura.Nested` for nested structures with validation, coercion, and generation
* `0.4.2` — [BUG] Fixed wrong spec for `put!/3`
* `0.4.1` — `Estructura.LazyMap.keys/1`, `Estructura.LazyMap.fetch_all/1`
* `0.4.0` — `Estructura.Lazy`, `Estructura.LazyMap`
* `0.3.2` — `put!/3`
* `0.3.0` — `coercion` and `validation` are now injected as behaviours
* `0.2.0` — `coercion`, `validation`, `put/3`

## [Documentation](https://hexdocs.pm/estructura)