JSON Schema macro generator




A JSONSchema -> Elixir macro

Currently supports JSONSchema drafts 4, 6, 7, 2019, 2020. except:

  • integer filters do not match exact integer floating point values.
  • multipleOf is not supported for number types. This is because elixir does not support a floating point remainder guard, and also because it is impossible for a floating point to guarantee sane results (e.g. for IEEE Float64, 1.2 / 0.1 != 12)
  • currently remoteref is not supported.
  • 'definitions' is disabled in pre-draft-7, for now. Please use absolute refs.

Works in progress:

  • support for remoteref
  • support for unevaluatedItems, unevaluatedProperties
  • support for contentMediaType
  • support for contentEncoding
  • support for named anchors
  • better uri support
  • support for function_from_map
  • support for more formatted strings


  • by default, ALL strings are considered to be invalid unless they are valid UTF-8 encodings and will be validated. If you require a raw binary, (for example if you are ingesting raw data in multipart/form-encoded, use the {"format": "binary"} filter on your string.
  • some parts of the public API e.g. function_from_* options may change to better suit the standard.

String formatting included:

  • date-time
  • date
  • time
  • ipv4
  • ipv6


Add the following lines to your mix.exs

  defp deps do
      {:exonerate, "~> 0.1", runtime: false},

Quick Start

defmodule SchemaModule do
  require Exonerate

  @doc """
  validates our input
  Exonerate.function_from_string(:def, :validate_input, """
iex> SchemaModule.validate_input("some string")
{:error, schema_pointer: "#", error_value: "some string", json_pointer: "#/parameter"}}

iex> SchemaModule.validate_input(%{"parameter" => "2"})
{:error, schema_pointer: "#/properties/parameter", error_value: "2", json_pointer: "#/parameter"}}

iex> SchemaModule.validate_input(%{"parameter" => 2})

Licensing notes

This software contains verbatim code from https://github.com/json-schema-org/JSON-Schema-Test-Suite which is copyright Julian Berman, et. al, and released under the MIT license.