ex_json_schema

# Elixir JSON Schema Validator

[![Build Status](https://github.com/jonasschmidt/ex_json_schema/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/jonasschmidt/ex_json_schema/actions/workflows/ci.yml)
[![Coverage Status](https://coveralls.io/repos/github/jonasschmidt/ex_json_schema/badge.svg?branch=master)](https://coveralls.io/github/jonasschmidt/ex_json_schema?branch=master)
[![Module Version](https://img.shields.io/hexpm/v/ex_json_schema.svg)](https://hex.pm/packages/ex_json_schema)
[![Hex Docs](https://img.shields.io/badge/hex-docs-lightgreen.svg)](https://hexdocs.pm/ex_json_schema/)
[![Total Download](https://img.shields.io/hexpm/dt/ex_json_schema.svg)](https://hex.pm/packages/ex_json_schema)
[![License](https://img.shields.io/hexpm/l/ex_json_schema.svg)](https://github.com/jonasschmidt/ex_json_schema/blob/master/LICENSE)
[![Last Updated](https://img.shields.io/github/last-commit/jonasschmidt/ex_json_schema.svg)](https://github.com/jonasschmidt/ex_json_schema/commits/master)

A JSON Schema validator with support for the draft 4, draft 6 and draft 7 specifications. Passes the official [JSON Schema Test Suite](https://github.com/json-schema/JSON-Schema-Test-Suite).

## Installation

Add the project to your Mix dependencies in `mix.exs`:

```elixir
defp deps do
  [
    {:ex_json_schema, "~> 0.11.5"}
  ]
end
```

Update your dependencies with:

```shell
$ mix deps.get
```

### Loading remote schemata

If you have remote schemata that need to be fetched at runtime, you have to register a function that takes a URL and returns a `Map` of the parsed JSON. So in your Mix configuration in `config/config.exs` you should have something like this:

```elixir
config :ex_json_schema,
  :remote_schema_resolver,
  fn url -> HTTPoison.get!(url).body |> Jason.decode! end
```

Alternatively, you can specify a module and function name for situations where using anonymous functions is not possible (i.e. working with Erlang releases):

```elixir
config :ex_json_schema,
  :remote_schema_resolver,
  {MyModule, :my_resolver}
```

You do not have to do that for the official draft 4 meta-schema found at http://json-schema.org/draft-04/schema# though. That schema is bundled with the project and will work out of the box without any network calls.

### Resolving a schema

In this step the schema is validated against its meta-schema (the draft 4 schema definition) and `$ref`s are being resolved (making sure that the reference points to an existing fragment). You should only resolve a schema once to avoid the overhead of resolving it in every validation call.

```elixir
schema = %{
  "type" => "object",
  "properties" => %{
    "foo" => %{
      "type" => "string"
    }
  }
} |> ExJsonSchema.Schema.resolve()
```

Note that `Map` keys are expected to be strings, since in practice that data will always come from some JSON parser.

## Usage

If you're only interested in whether a piece of data is valid according to the schema:

```elixir
iex> ExJsonSchema.Va