# AshJason
[](https://hex.pm/packages/ash_jason)
[](https://hexdocs.pm/ash_jason/)
[](https://github.com/vonagam/ash_jason/blob/master/LICENSE.md)
Ash resource extension for implementing `Jason.Encoder` protocol.
## Installation
Add to the deps:
```elixir
def deps do
[
{:ash_jason, "~> 2.0.0"},
]
end
```
## Usage
Add `AshJason.Resource` to `extensions` list within `use Ash.Resource` options:
```elixir
defmodule Example.Resource do
use Ash.Resource,
extensions: [AshJason.Resource]
end
```
### Configuration
Producing json object can have multiple steps:
- Picking keys from a record.
- Merging some values.
- Renaming keys.
- Ordering keys.
- Customizing a result with a function.
By default only the picking step happens and it takes all non-private non-sensitive fields
(attributes, relationships, aggregates, calculations) with loaded non-nil values from a record.
For adding and configuring those steps there is an optional `jason` dsl section:
```elixir
defmodule Example.Resource do
use Ash.Resource,
extensions: [AshJason.Resource]
jason do
# options
end
end
```
All optional steps can be specified multiple times and are applied in the order they were defined in.
A result object on which those steps operate is a key-value list - not map, not keyword list.
- Unlike map the order is stable and guaranteed.
- Unlike keyword list it can have string keys.
#### `pick`
Keys to pick from a record and include in the result.
Accepts a fixed explicit list of keys or a map with a configuration of default behaviour.
Values of `nil`/`Ash.NotLoaded`/`Ash.ForbiddenField` are omitted.
Map can have such options as:
- `private?` - Whenever to pick private fields.
- `sensitive?` - Whenever to pick sensitive fields.
- `include` - Keys to pick. In addition to fields.
- `exclude` - Keys not to pick.
```elixir
jason do
# Pick only those listed keys
pick [:only_some_field]
# Pick non-sensitive fields
pick %{private?: true}
# Pick non-private fields
pick %{sensitive?: true}
# Pick all fields
pick %{private?: true, sensitive?: true}
# Pick usual but include and exclude some specific keys
pick %{include: [:ok_private_field], exclude: [:irrelevant_public_field]}
end
```
#### `merge`
A step to merge values into a result.
Accepts a map or a tuples list.
Map has no guarantees about keys order so if you care about that prefer the list form.
```elixir
jason do
# Merge with map
merge %{key: "value"}
# Merge with list
merge key: "value"
end
```
#### `rename`
A step to rename keys in a result.
Accepts a map, a tuples list or a function for mapping.
```elixir
jason do
# Rename with map
rename %{from_key: "to_key"}
# Rename with list
rename from_key: "to_key"
# Rename with a function
rename fn name -> String.capitalize(to_string(name)) end
end
```
#### `order`
A step to reorder keys in a result.
Accepts a boolean, a sort function or a list of keys in a desired order.
If it is a list then it also acts as a filter and removes keys not present in that list.
```elixir
jason do
# Order with standard `Enum.sort`
order true
# Order with a custom sort function
order fn keys -> Enum.sort(keys, :desc) end
# Order in accordance with a list
order [:only, :these, :keys, :in, :that, "order"]
end
```
#### `customize`
A step to arbitrary customize a result.
Accepts a function that will get a result and a resource record as arguments and return a modifed result.
As mentioned above a result has a form of a list with two elements, key and value, tuples.
To work with it you might want to use `List` methods like `List.keytake` or `List.keystore`.
```elixir
jason do
customize fn result, _record ->
result |> List.keystore(:custom_key, 0, {:custom_key, "custom_value"})
end
end
```
## Links
[`Jason` docs](https://hexdocs.pm/jason).
