# `AvroEx`
[🔗](https://github.com/beam-community/avro_ex/blob/v2.2.1/lib/avro_ex.ex#L1)

AvroEx is a library for encoding and decoding data with Avro schemas.
Supports parsing schemas, encoding data, and decoding data.

For encoding and decoding, the following type chart should be referenced:

| Avro Types | Elixir Types |
|------------|:------------:|
| boolean | boolean |
| integer | integer |
| long | integer |
| float | decimal |
| double | decimal |
| bytes | binary |
| string | String.t, atom |
| null | nil |
| Record | map |
| Enum | String.t, atom (corresponding to the enum's symbol list) |

# `encoded_avro`

```elixir
@type encoded_avro() :: binary()
```

# `decode`

```elixir
@spec decode(AvroEx.Schema.t(), encoded_avro(), keyword()) ::
  {:ok, term()} | {:error, AvroEx.DecodeError.t()}
```

Given an encoded message and its accompanying schema, decodes the message.

    iex> schema = AvroEx.decode_schema!("boolean")
    iex> AvroEx.decode(schema, <<1>>)
    {:ok, true}

## Tagged unions

When decoding one can set the option `tagged_unions: true` to decode union
values as a tagged tuple of `{name, value}` instead of just the plain `value`.
This allows to retain the information about which union schema was used for
encoding when this cannot be infered from the `value` alone.

## Decimals

Specify the option `decimals: :exact` to use `Decimal.new/3` to parse decimals
into a Decimal struct with arbitrary precision.

Otherwise, an approximate number is calculated.

# `decode!`

```elixir
@spec decode!(AvroEx.Schema.t(), encoded_avro(), keyword()) :: term()
```

Same as decode/2, but returns raw decoded value.

Raises `t:AvroEx.DecodeError.t/0` on error.

For documentation of `opts` see `decode/3`.

## Examples

    iex> schema = AvroEx.decode_schema!("string")
    iex> encoded = AvroEx.encode!(schema, "hello")
    iex> AvroEx.decode!(schema, encoded)
    "hello"

# `decode_schema`

```elixir
@spec decode_schema(term(), Keyword.t()) ::
  {:ok, AvroEx.Schema.t()} | {:error, AvroEx.Schema.DecodeError.t()}
```

Given an Elixir or JSON-encoded schema, parses the schema and returns a `t:AvroEx.Schema.t/0` struct representing the schema.

Errors for invalid JSON, invalid schemas, and bad name references.

## Options
* `:strict` - whether to strictly validate the schema, defaults to `false`. Recommended to turn this on for locally owned schemas, but not for interop with external schemas.

## Examples

    iex> AvroEx.decode_schema("string")
    {:ok, %AvroEx.Schema{schema: %AvroEx.Schema.Primitive{type: :string}}}

    iex> json= ~S({"fields":[{"name":"a","type":"string"}],"name":"my_type","type":"record"})
    iex> {:ok, %Schema{schema: record}} = AvroEx.decode_schema(json)
    iex> match?(%Record{}, record)
    true

# `decode_schema!`

```elixir
@spec decode_schema!(term(), Keyword.t()) :: AvroEx.Schema.t()
```

Same as `AvroEx.decode_schema/1`, but raises an exception on failure instead of
returning an error tuple.

## Examples

    iex> AvroEx.decode_schema!("int")
    %AvroEx.Schema{schema: %AvroEx.Schema.Primitive{type: :int}}

# `encodable?`

```elixir
@spec encodable?(AvroEx.Schema.t(), any()) :: boolean()
```

Checks to see if the given data is encodable using the given schema. Helpful for unit testing.

    iex> AvroEx.encodable?(%Schema{schema: %Primitive{type: :string}}, "wut")
    true

    iex> AvroEx.encodable?(%Schema{schema: %Primitive{type: :string}}, 12345)
    false

# `encode`

```elixir
@spec encode(AvroEx.Schema.t(), term(), keyword()) ::
  {:ok, encoded_avro()} | {:error, AvroEx.EncodeError.t() | Exception.t()}
```

Given `t:AvroEx.Schema.t/0` and `term()`, takes the data and encodes it according to the schema.

## Examples

    iex> schema = AvroEx.decode_schema!("int")
    iex> AvroEx.encode(schema, 1234)
    {:ok, <<164, 19>>}

## Tagged unions

When supplying a union value one can optionally supply a tagged tuple of `{name, value}`
instead of just the plain `value` to force encoding the value as the named type
found using `name` instead of matching by the shape of `value`. This can improve
performance and allows forcing a selected named type even if the shape of the
data is the same. See also the "Tagged unions" section on `decode/3`.

## Array encoding

Array encoding may add an additional `long` encoded integer to put the byte size
of blocks with their counts. This allows consumers of the encoded data to skip
over those blocks in an efficient manner. Using the option `include_block_byte_size: true`
enables adding those additional values.

# `encode!`

```elixir
@spec encode!(AvroEx.Schema.t(), term(), keyword()) :: encoded_avro()
```

Same as `encode/2`, but returns the encoded value directly.

Raises `t:AvroEx.EncodeError.t/0` on error.

For documentation of `opts` see `encode/3`.

## Examples

    iex> schema = AvroEx.decode_schema!("boolean")
    iex> AvroEx.encode!(schema, true)
    <<1>>

# `encode_schema`

```elixir
@spec encode_schema(AvroEx.Schema.t(), Keyword.t()) :: String.t()
```

Encodes the given schema to JSON

## Options
* `canonical` - Encodes the schema into its [Parsing Canonical Form](https://avro.apache.org/docs/current/spec.html#Parsing+Canonical+Form+for+Schemas), default `false`

## Examples

    iex> schema = AvroEx.decode_schema!(%{"type" => "int", "logicalType" => "date"})
    iex> AvroEx.encode_schema(schema)
    ~S({"type":"int","logicalType":"date"})

    iex> schema = AvroEx.decode_schema!(%{"type" => "int", "logicalType" => "date"})
    iex> AvroEx.encode_schema(schema, canonical: true)
    ~S("int")

# `named_type`

> This function is deprecated. Use AvroEx.Schema.Context.lookup/2.

```elixir
@spec named_type(
  AvroEx.Schema.full_name(),
  AvroEx.Schema.t() | AvroEx.Schema.Context.t()
) ::
  nil | AvroEx.Schema.schema_types()
```

# `parse_schema`

> This function is deprecated. Use AvroEx.decode_schema/1 instead.

```elixir
@spec parse_schema(AvroEx.Schema.json_schema()) ::
  {:ok, AvroEx.Schema.t()} | {:error, AvroEx.Schema.DecodeError.t()}
```

# `parse_schema!`

> This function is deprecated. Use AvroEx.decode_schema!/1 instead.

```elixir
@spec parse_schema!(AvroEx.Schema.json_schema()) :: AvroEx.Schema.t() | no_return()
```

---

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