From e388192851cbdc8bb08561ab0e211e8390d15ada Mon Sep 17 00:00:00 2001
From: Danielwhyte <danwhy@gmail.com>
Date: Wed, 24 Oct 2018 12:22:25 +0100
Subject: [PATCH] raises error if required fields are missing, #5

---
 lib/alog.ex        | 28 ++++++++++++++++++++++
 test/alog_test.exs | 60 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/lib/alog.ex b/lib/alog.ex
index 1fe6210..b6e456a 100644
--- a/lib/alog.ex
+++ b/lib/alog.ex
@@ -30,6 +30,12 @@ defmodule Alog do
 
   Alog expects your `Repo` to belong to the same base module as the schema.
   So if your schema is `MyApp.User`, or `MyApp.Accounts.User`, your Repo should be `MyApp.Repo`.
+
+  Any schema that uses Alog must include the fields `:deleted` of type `:boolean` and default false,
+  and `:entry_id` of type `:string`.
+
+        field(:deleted, :boolean, default: false)
+        field(:entry_id, :string)
   """
 
   @callback insert(struct) :: {:ok, Ecto.Schema.t()} | {:error, Ecto.Changeset.t()}
@@ -53,6 +59,28 @@ defmodule Alog do
 
       @repo __MODULE__ |> Module.split() |> List.first() |> Module.concat("Repo")
 
+      if not Map.has_key?(%__MODULE__{}, :deleted) || not is_boolean(%__MODULE__{}.deleted) do
+        raise """
+
+        Your Schema must have a key :deleted, with type :boolean and default false.
+
+        Add the following line to your schema:
+
+            field(:deleted, :boolean, default: false)
+        """
+      end
+
+      if not Map.has_key?(%__MODULE__{}, :entry_id) do
+        raise """
+
+        Your Schema must have a key :entry_id, with type :string
+
+        Add the following line to your schema:
+
+            field(:entry_id, :string)
+        """
+      end
+
       @doc """
       Applies a schema's changeset function and inserts it into the database.
       Adds an entry id to link it to future updates of the item.
diff --git a/test/alog_test.exs b/test/alog_test.exs
index 6b9d05d..1469150 100644
--- a/test/alog_test.exs
+++ b/test/alog_test.exs
@@ -83,4 +83,64 @@ defmodule AlogTest do
       assert length(User.all()) == 0
     end
   end
+
+  describe "required fields" do
+    test "schema without delete field raises error" do
+      assert_raise RuntimeError, fn ->
+        defmodule BadSchema do
+          use Ecto.Schema
+          use Alog
+
+          schema "bad_schema" do
+            field(:entry_id, :string)
+            timestamps()
+          end
+        end
+      end
+    end
+
+    test "schema without entry_id field raises error" do
+      assert_raise RuntimeError, fn ->
+        defmodule BadSchema do
+          use Ecto.Schema
+          use Alog
+
+          schema "bad_schema" do
+            field(:deleted, :boolean, default: false)
+            timestamps()
+          end
+        end
+      end
+    end
+
+    test "schema with deleted field of wrong type raises error" do
+      assert_raise RuntimeError, fn ->
+        defmodule BadSchema do
+          use Ecto.Schema
+          use Alog
+
+          schema "bad_schema" do
+            field(:entry_id, :string)
+            field(:deleted, :string)
+            timestamps()
+          end
+        end
+      end
+    end
+
+    test "both required fields do not raise error" do
+      assert (fn ->
+                defmodule BadSchema do
+                  use Ecto.Schema
+                  use Alog
+
+                  schema "bad_schema" do
+                    field(:entry_id, :string)
+                    field(:deleted, :boolean, default: false)
+                    timestamps()
+                  end
+                end
+              end).()
+    end
+  end
 end