Public API

lib/validation.ex

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+defmodule Validation do
+  @moduledoc """
+  Contains top level convenience functions and macros that map into deeper modules
+  """
+
+  @doc """
+  Creates a schema using the DSL
+  """
+  defmacro schema(do: spec) do
+    spec = Macro.escape(spec)
+    quote do
+      Validation.DSL.parse_schema(unquote(spec))
+    end
+  end
+end

lib/validation/dsl.ex

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+defmodule Validation.DSL do
+  @moduledoc """
+  Functions that make it simple to create schemas
+  """
+
+  alias Validation.Predicates
+  alias Validation.Rules
+  alias Validation.Schema
+
+  @type schema_ast :: any
+
+  @doc """
+  Creates a schema from the AST specification
+  """
+  @spec parse_schema(schema_ast) :: Schema.t
+  def parse_schema(spec) do
+    rules = parse_rules(spec)
+    Schema.build(rules, %{})
+  end
+
+  defp parse_rules({:__block__, _, rules}) when is_list(rules) do
+    rules
+    |> Enum.flat_map(&parse_rules/1)
+  end
+  defp parse_rules({:required, _, [field]}) do
+    key_rule = Rules.RequiredKey.build(field)
+    [key_rule]
+  end
+  defp parse_rules({:required, _, [field, predicate_spec]}) do
+    predicate = parse_predicate(predicate_spec)
+
+    value_rule = Rules.Value.build(field, predicate)
+    key_rule = Rules.RequiredKey.build(field)
+
+    [key_rule, value_rule]
+  end
+
+  defp parse_predicate({:filled?, _, nil}) do
+    Predicates.Filled.build
+  end
+end

test/dsl_test.exs

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+defmodule Validation.DSLTest do
+  use ExUnit.Case, async: true
+
+  require Validation
+  alias Validation.Schema
+
+  test "very simple schema" do
+    schema = Validation.schema do
+      required(:name, filled?)
+    end
+
+    params = %{name: "John"}
+    result = Schema.apply(schema, params)
+    assert result.valid?
+
+    params = %{first_name: "John"}
+    result = Schema.apply(schema, params)
+    refute result.valid?
+  end
+
+  test "multiple fields" do
+    schema = Validation.schema do
+      required(:name, filled?)
+      required(:email, filled?)
+    end
+
+    params = %{name: "John", email: "[email protected]"}
+    result = Schema.apply(schema, params)
+    assert result.valid?
+
+    params = %{name: "John"}
+    result = Schema.apply(schema, params)
+    refute result.valid?
+    assert result.errors == %{email: ["is missing", "must be filled"]}
+  end
+
+  test "no predicate" do
+    schema = Validation.schema do
+      required(:name)
+    end
+
+    params = %{name: ""}
+    result = Schema.apply(schema, params)
+    assert result.valid?
+
+    params = %{first_name: "John"}
+    result = Schema.apply(schema, params)
+    refute result.valid?
+    assert result.errors == %{name: ["is missing"]}
+  end
+
+  @tag :skip
+  test "optional field"
+
+  @tag :skip
+  test "nested schema"
+
+  @tag :skip
+  test "custom predicate"
+
+  @tag :skip
+  test "custom predicate combined with a built-in one"
+
+  @tag :skip
+  test "custom rule"
+
+  @tag :skip
+  test "white list"
+
+  @tag :skip
+  test "strict"
+end