# gleam_jsone
[](https://hex.pm/packages/gleam_jsone) [](https://hexdocs.pm/gleam_jsone/)
Gleam bindings to the fast, simple JSON decoding/encoding Erlang library,
[`jsone`](https://github.com/sile/jsone).
This library will always aim to track the latest `jsone` release. You can find
the latest `jsone` documentation [here](https://hexdocs.pm/jsone/).
Although fully functional, **please note** that this library currently has very
unhelpful error messages. If you are using it and would like better, please open
an issue (or, of course, a PR)!
Once we have nice error messages, we'll be ready for v1.0.0!
## Installation
Add `gleam_jsone` to the deps section of your `rebar.config` file.
```erlang
{deps, [
{gleam_jsone, "0.3.1"}
]}.
```
## Examples
This library allows you to decode JSON `String`s into Erlang `Dynamic` data. In
order to turn that into Gleam data, you'll either need to use the functions for
`Dynamic` data in the Gleam standard library, or a library like
[`gleam_decode`](https://github.com/rjdellecese/gleam_decode). The examples
below use the standard library functions, but you can check out the test suite
for examples that use `gleam_decode`.
```rust
import gleam/dynamic
import gleam/jsone
import gleam/result
pub fn decode_json_int() -> Result(Int, String) {
"1"
|> jsone.decode
|> result.then(fn(json_dynamic) {
dynamic.int(json_dynamic)
}) //=> Ok(1)
};
pub fn decode_json_object_field() -> Result(Bool, String) {
"{ \"boolean\": true }"
|> jsone.decode
|> result.then(fn(json_dynamic) {
dynamic.field(json_dynamic, "boolean")
})
|> result.then(fn(boolean_field_dynamic) {
dynamic.bool(boolean_field_dynamic)
}) //=> Ok(true)
};
pub type JsonObject {
JsonObject(
boolean: Bool,
int: Int
)
};
pub fn decode_json_object() -> Result(JsonObject, String) {
let dynamic_object_result =
"
{
\"boolean\": true,
\"int\": 1
}
"
|> jsone.decode
let boolean_value_result =
dynamic_object_result
|> result.then(fn(dynamic_object) {
dynamic_object
|> dynamic.field("boolean")
|> result.then(fn(dynamic_boolean) {
dynamic.bool(dynamic_boolean)
})
})
let int_value_result =
dynamic_object_result
|> result.then(fn(dynamic_object) {
dynamic_object
|> dynamic.field("int")
|> result.then(fn(dynamic_int) {
dynamic.int(dynamic_int)
})
})
case boolean_value_result, int_value_result {
Ok(boolean_value), Ok(int_value) -> Ok(JsonObject(boolean_value, int_value))
_, _ -> Error("Couldn't decode JSON into JsonObject.")
} //=> Ok(JsonObject(true, 1))
};
pub fn decode_bad_json() -> Result(Int, String) {
"<1x.1"
|> jsone.decode
|> result.then(fn(json_dynamic) {
dynamic.int(json_dynamic)
}) //=> Error("Invalid JSON value")
}
```
