# JsonXema
[](https://travis-ci.org/hrzndhrn/json_xema)
[](https://coveralls.io/github/hrzndhrn/json_xema?branch=master)
[](https://opensource.org/licenses/MIT)
JsonXema is a [JSON Schema](http://json-schema.org) validator with support
for draft 04, 06, and 07.
JsonXema based on elixir schema validator
[Xema](https://github.com/hrzndhrn/xema).
Xema is in early beta. If you try it and has an issue, report them.
## Installation
If [available in Hex](https://hex.pm), the package can be installed
like this:
First, add JsonXema to your `mix.exs` dependencies:
```elixir
def deps do
[
{:json_xema, "~> 0.1"}
]
end
```
Then, update your dependencies:
```shell
$ mix deps.get
```
## Usage
A JSON parser is required to create a schema from JSON. It is also possible to
create a schema directly from an elixir data structure. There are three functions available to validate data against a schema.
+ `JsonXema.valid?/2` gets a schema and any data and returns `true` for valid
data and `false` otherwise.
+ `JsonXema.validate/2` gets a schema and any data and returns `:ok` for valid
data and an error tuple otherwise.
+ `JsonXema.validate!/2` gets a schema and any data and returns `:ok` for valid
data and raised an exception otherwise.
```elixir
iex> schema = """
...> {
...> "type": "object",
...> "properties": {
...> "name": {
...> "type": "string",
...> "min_length": 3
...> },
...> "age": {
...> "type": "integer",
...> "minimum": 0
...> }
...> },
...> "additionalProperties": false
...> }
...> """
...> |> Jason.decode!()
...> |> JsonXema.new()
...>
...> data = Jason.decode!("""
...> {"name": "John", "age": 42}
...> """)
...> JsonXema.valid?(schema, data)
true
...> JsonXema.valid?(schema, %{"name" => "Peter", "age" => -55})
false
...> JsonXema.valid?(schema, %{"name" => "Peter", "old" => 55})
false
...> JsonXema.validate(schema, %{"name" => "Peter", "age" => -55})
{:error, %{properties: %{"age" => %{minimum: 0, value: -55}}}}
...> JsonXema.validate(schema, %{"name" => "Peter", "old" => 55})
{:error, %{properties: %{"old" => %{additionalProperties: false}}}}
```
## Unsupported semantic validation
For now, the keyword `format` do not support the following formats:
+ `idn-email` the I18N equivalent of `email`
+ `idn-hostname` I18N equivalent of `hostname`
+ `iri` the I18N equivalent of `uri`
+ `iri-reference` the I18N equivalent of `uri-reference`
## Tests
Tests in [test/json_xema](test/json_xema) are not organised as classic unit
tests but are related to JSON schema keywords or a specific feature.
The directory [test/suite](test/suite) contains tests for draft 04, 06, and 07
and are generated from the
[Json Schema Test Suite](https://github.com/json-schema-org/JSON-Schema-Test-Suite).
## References
The home of JSON Schema: http://json-schema.org/
Specification:
* Draft-04
* [JSON Schema core](http://json-schema.org/draft-04/json-schema-core.html)
defines the basic foundation of JSON Schema
* [JSON Schema Validation](http://json-schema.org/draft-04/json-schema-validation.html)
defines the validation keywords of JSON Schema
* Draft-06
* [JSON Schema core](http://json-schema.org/draft-06/json-schema-core.html)
* [JSON Schema Validation](http://json-schema.org/draft-06/json-schema-validation.html)
* [JSON Schema Release Notes](http://json-schema.org/draft-06/json-schema-release-notes.html)
contains informations to migrate schemas.
* Draft-07
* [JSON Schema core](http://json-schema.org/draft-07/json-schema-core.html)
* [JSON Schema Validation](http://json-schema.org/draft-07/json-schema-validation.html)
* [JSON Schema Release Notes](http://json-schema.org/draft-07/json-schema-release-notes.html)
[Understanding JSON Schema](https://spacetelescope.github.io/understanding-json-schema/index.html)
a great tutorial for JSON Schema authors.
