Optimal

A schema based opt validator. Its verbose, but I’ve tried many other data validation libraries, and their succinctness came with a cost when it came to features. There are a lot of optimizations and improvements that can be made, so contributions are very welcome.

View the documentation: https://hexdocs.pm/optimal

Installation

If available in Hex, the package can be installed by adding optimal to your list of dependencies in mix.exs:

def deps do
  [
    {:optimal, "~> 0.2.0"}
  ]
end

Examples

# Allow no opts
Optimal.schema()

# Allow any opts
Optimal.schema(extra_keys?: true)

# Allow a specific set of opts
Optimal.schema(opts: [:foo, :bar, :baz])

# Allow specific types
Optimal.schema(opts: [foo: :int, bar: :string, baz: :pid])

# Require certain opts
Optimal.schema(opts, [foo: :int, bar: :string, baz: :pid], required: [:foo, :bar])

# Provide defaults for arguments (defaults will have to pass any type validation)
# If they provide they key, but a `nil` value, the default is *not* used.
Optimal.schema(opts, [foo: :int, bar: :string, baz: :boolean], defaults: [baz: true])

# Allow only specific values for certain opts
Optimal.schema(opts, [foo: :int], allow_values: [foo: [1, 2, 3]])
# Or as an enum type
Optimal.schema(opts, [foo: {:enum, [1, 2, 3]}])

# Custom validations
# Read below for more info
def custom(field_value, field_name, all_opts, schema) do
  if is_special(field_value) do
    :ok
  else
    [{field_name, "must be special"}]
  end
end

Optimal.schema(opts, [foo: :integer, bar: :string], custom: [&custom/4])

Types

Scalar Types

  • :any
  • :atom
  • :binary
  • :bitstring
  • :boolean
  • :float
  • :function
  • :int
  • :integer
  • :keyword
  • :list
  • :string
  • :map
  • :nil
  • :number
  • :pid
  • :port
  • :reference
  • :tuple
  • :struct

Composite/Complex Types

  • {:keyword, value_type} - Keyword where all values are of type value_type
  • {:list, type} - List where all values are of type value_type
  • {:function, arity} - A function with the arity given by arity
  • {:struct, Some.Struct} - An instance of Some.Struct
  • %Some.Struct{} - Same as {:struct, Some.Struct}
  • {:enum, [value1, value2]} - Allows any value in the list.

Custom Validations

Custom validations have the ability to add arbitrary errors, and additionally they can modify the opts as they pass through. They are run in order, and unlike all built in validations, they are only run on valid opts.

Examples

# Simple (returning booleans)
def is_ten(field_value, _, _, _) do
  field_value == 10
end

# Custom errors (ok/error tuples)
def is_ten(field_value, field, _, _) do
  if field_value == 10 do
    :ok
  else
    {:error, {field, "should really have equaled ten"}}
  end
end

# Returning a list of errors
def greater_than_1_and_even(field_value, field, _, _) do
  errors =
    if field_value > 1 do
      []
    else
      [{field, "should be greater than 1}]
    end

  if Integer.is_even(field_value) do
    errors
  else
    [{field, "should be even} | errors]
  end
end

Schema merging

This behavior is not set in stone, and will probably need to take a strategy option to support different kinds of merging opt schemas. We’ve noticed this is very helpful with certain patterns like building a DSL, where all forms of something take a certain set of args, but a specific form allows more args and/or additional types for that set arg.


schema1 = Optimal.schema(opts: [foo: :int])
schema2 = Optimal.schema(opts: [foo: :string, bar: :int])

Optimal.merge(schema1, schema2) == Optimal.schema(opts: [foo: [:int, :string], bar: :int])