# `RustyJson.Helpers`
[🔗](https://github.com/jeffhuen/rustyjson/blob/v0.3.9/lib/helpers.ex#L1)

Compile-time helpers for JSON encoding, compatible with Jason's `Helpers` module.

Provides macros that pre-encode JSON object keys at compile time
for faster runtime encoding.

## Examples

    import RustyJson.Helpers

    def render(user) do
      json_map(name: user.name, email: user.email)
    end

    def render_partial(user) do
      json_map_take(user, [:name, :email])
    end

# `json_map`
*macro* 

Encodes a keyword list as a JSON object with keys pre-encoded at compile time.

Values are encoded at runtime. Returns a `%RustyJson.Fragment{}`.

Keys must be atoms with ASCII printable characters only (no `\`, `/`, `"`).

## Examples

    iex> import RustyJson.Helpers
    iex> fragment = json_map(name: "Alice", age: 30)
    iex> RustyJson.encode!(fragment, protocol: true)
    ~s({"name":"Alice","age":30})

# `json_map_take`
*macro* 

Encodes selected keys from a map as a JSON object with keys pre-encoded at compile time.

Takes a map and a compile-time list of atom keys. Values are looked up and
encoded at runtime. Returns a `%RustyJson.Fragment{}`.

Raises `ArgumentError` at runtime if the map is missing any of the specified keys.

## Examples

  iex> import RustyJson.Helpers
  iex> user = %{name: "Alice", age: 30, email: "alice@example.com"}
  iex> fragment = json_map_take(user, [:name, :age])
  iex> RustyJson.encode!(fragment, protocol: true)
  ~s({"name":"Alice","age":30})

---

*Consult [api-reference.md](api-reference.md) for complete listing*