# Zoi
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---
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`Zoi` is a schema validation library for Elixir, designed to provide a simple and flexible way to define and validate data.
## Installation
`zoi` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:zoi, "~> 0.6"}
]
end
```
## Usage
You can create schemas for various data types, including strings, integers, floats, booleans, arrays, maps, and more. `Zoi` supports a wide range of validation rules and transformations.
### Parsing Data
Here's a simple example of how to use `Zoi` to validate a string:
```elixir
# Define a schema with a string type
iex> schema = Zoi.string() |> Zoi.min(3)
iex> Zoi.parse(schema, "hello")
{:ok, "hello"}
iex> Zoi.parse(schema, "hi")
{:error, [%Zoi.Error{message: "too small: must have at least 3 characters"}]}
# Add transforms to a schema
iex> schema = Zoi.string() |> Zoi.trim()
iex> Zoi.parse(schema, " world ")
{:ok, "world"}
```
You can also validate structured maps:
```elixir
# Validate a structured data in a map
iex> schema = Zoi.object(%{name: Zoi.string(), age: Zoi.integer(), email: Zoi.email()})
iex> Zoi.parse(schema, %{name: "John", age: 30, email: "john@email.com"})
{:ok, %{name: "John", age: 30, email: "john@email.com"}}
iex> Zoi.parse(schema, %{email: "invalid-email"})
{:error, [
%Zoi.Error{path: [:name], message: "is required"},
%Zoi.Error{path: [:age], message: "is required"},
%Zoi.Error{path: [:email], message: "invalid email format"}
]}
```
and arrays:
```elixir
# Validate an array of integers
iex> schema = Zoi.array(Zoi.integer() |> Zoi.min(0)) |> Zoi.min(2)
iex> Zoi.parse(schema, [1, 2, 3])
{:ok, [1, 2, 3]}
iex> Zoi.parse(schema, [1, "2"])
{:error, [%Zoi.Error{path: [1], message: "invalid type: must be an integer"}]}
```
And many more possibilities, including nested schemas, custom validations and data transformations. Check the official [docs](https://hexdocs.pm/zoi) for more details.
## Types
`Zoi` can infer types from schemas, allowing you to leverage Elixir's `@type` and `@spec` annotations for documentation
```elixir
defmodule MyApp.Schema do
@schema Zoi.string() |> Zoi.min(2) |> Zoi.max(100)
@type t :: unquote(Zoi.type_spec(@schema))
end
```
This will generate the following type specification:
```elixir
@type t :: binary()
```
This also applies to complex types, such as `Zoi.object/2`:
```elixir
defmodule MyApp.User do
@schema Zoi.object(%{
name: Zoi.string() |> Zoi.min(2) |> Zoi.max(100),
age: Zoi.integer() |> Zoi.optional(),
email: Zoi.email()
})
@type t :: unquote(Zoi.type_spec(@schema))
end
```
Which will generate:
```elixir
@type t :: %{
required(:name) => binary(),
optional(:age) => integer(),
required(:email) => binary()
}
```
### Errors
When validation fails, `Zoi` returns a list of errors, each containing a message and the path to the invalid data. Even when erros are nested, `Zoi` will return all errors in a flattened list.
```elixir
iex> schema = Zoi.object(%{name: Zoi.string(), age: Zoi.integer()})
iex> Zoi.parse(schema, %{name: 123, age: "thirty"})
{:error, [
%Zoi.Error{path: [:name], message: "invalid type: must be a string"},
%Zoi.Error{path: [:age], message: "invalid type: must be an integer"}
]}
```
You can view the error in a map format using the `Zoi.treefy_errors/1` function:
```elixir
iex> Zoi.treefy_errors(errors)
%{
name: ["invalid type: must be a string"],
age: ["invalid type: must be an integer"]
}
```
You can also customize error messages:
```elixir
iex> schema = Zoi.string(error: "not a string")
iex> Zoi.parse(schema, :hi)
{:error, [%Zoi.Error{message: "not a string"}]}
```
## Acknowledgements
`Zoi` is inspired by [Zod](https://zod.dev/) and [Joi](https://joi.dev/), providing a similar experience for Elixir.
