defmodule AvroEx do
@moduledoc """
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) |
"""
alias AvroEx.Schema
alias AvroEx.Schema.Context
@type encoded_avro :: binary
@doc """
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
"""
@spec encodable?(AvroEx.Schema.t(), any) :: boolean
defdelegate encodable?(schema, data), to: AvroEx.Schema
@spec parse_schema(Schema.json_schema()) :: {:ok, Schema.t()} | {:error, AvroEx.Schema.DecodeError.t()}
@deprecated "Use AvroEx.decode_schema/1 instead"
def parse_schema(json), do: decode_schema(json, [])
@spec parse_schema!(Schema.json_schema()) :: Schema.t() | no_return
@deprecated "Use AvroEx.decode_schema!/1 instead"
def parse_schema!(json), do: decode_schema!(json, [])
@doc """
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
"""
@spec decode_schema(term(), Keyword.t()) :: {:ok, Schema.t()} | {:error, AvroEx.Schema.DecodeError.t()}
def decode_schema(schema, opts \\ []) do
try do
{:ok, decode_schema!(schema, opts)}
rescue
error -> {:error, error}
end
end
@doc """
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}}
"""
@spec decode_schema!(term(), Keyword.t()) :: Schema.t()
def decode_schema!(schema, opts \\ []) do
if is_binary(schema) and not Schema.Parser.primitive?(schema) do
schema
|> Jason.decode!()
|> Schema.Parser.parse!(opts)
else
Schema.Parser.parse!(schema, opts)
end
end
@doc """
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")
"""
@spec encode_schema(Schema.t(), Keyword.t()) :: String.t()
def encode_schema(%Schema{} = schema, opts \\ []) do
AvroEx.Schema.Encoder.encode(schema, opts)
end
@doc """
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.
"""
@spec encode(Schema.t(), term, keyword()) ::
{:ok, encoded_avro} | {:error, AvroEx.EncodeError.t() | Exception.t()}
def encode(schema, data, opts \\ []) do
AvroEx.Encode.encode(schema, data, opts)
end
@doc """
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>>
"""
@spec encode!(Schema.t(), term(), keyword()) :: encoded_avro()
def encode!(schema, data, opts \\ []) do
case AvroEx.Encode.encode(schema, data, opts) do
{:ok, data} -> data
{:error, error} -> raise error
end
end
@doc """
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.
"""
@spec decode(Schema.t(), encoded_avro, keyword()) ::
{:ok, term}
| {:error, AvroEx.DecodeError.t()}
def decode(schema, message, opts \\ []) do
case AvroEx.Decode.decode(schema, message, opts) do
{:ok, value, _} -> {:ok, value}
{:error, error} -> {:error, error}
end
end
@doc """
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"
"""
@spec decode!(Schema.t(), encoded_avro(), keyword()) :: term()
def decode!(schema, message, opts \\ []) do
case AvroEx.Decode.decode(schema, message, opts) do
{:ok, value, _} -> value
{:error, error} -> raise error
end
end
@deprecated "Use AvroEx.Schema.Context.lookup/2"
@spec named_type(Schema.full_name(), Schema.t() | Context.t()) :: nil | Schema.schema_types()
def named_type(name, %Schema{context: %Context{} = context}) when is_binary(name) do
named_type(name, context)
end
def named_type(name, %Context{} = context) do
Context.lookup(context, name)
end
end
