Initial Commit

.env

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+### Assoc
+
+# Database
+
+export ASSOC_TEST_POSTGRES_USER=postgres
+export ASSOC_TEST_POSTGRES_PASS=postgres
+export ASSOC_TEST_POSTGRES_HOST=localhost
+export ASSOC_TEST_POSTGRES_DB=assoc_test
+
+### Elixir Version
+
+export ELIXIR_VERSION="1.8.1"
+export PATH="$HOME/.kiex/elixirs/elixir-1.8.1/bin:$PATH"
+export MIX_ARCHIVES="$HOME/.kiex/mix/archives/elixir-1.8.1"

.env.travis

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+### Assoc
+
+# Database
+
+export ASSOC_TEST_POSTGRES_USER=postgres
+export ASSOC_TEST_POSTGRES_PASS=
+export ASSOC_TEST_POSTGRES_HOST=localhost
+export ASSOC_TEST_POSTGRES_DB=assoc_test
+
+### Elixir Version
+
+export ELIXIR_VERSION="1.8.1"
+export PATH="$HOME/.kiex/elixirs/elixir-1.8.1/bin:$PATH"
+export MIX_ARCHIVES="$HOME/.kiex/mix/archives/elixir-1.8.1"

.formatter.exs

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+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

.gitignore

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+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where 3rd-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+assoc-*.tar
+

CHANGELOG.md

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+# Changelog
+
+## [v0.1.0] - 2019-01-30
+
+- Initial Release 

README.md

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+# Assoc
+
+> An easy way to manage `many_to_many`, `has_many` and `belongs_to` Ecto associations

config/config.exs

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+use Mix.Config
+
+import_config "./#{Mix.env()}.exs"

config/dev.exs

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+use Mix.Config

config/prod.exs

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+use Mix.Config

config/test.exs

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+use Mix.Config
+
+# Set the log level
+#
+# The order from most information to least:
+#
+#   :debug
+#   :info
+#   :warn
+#
+config :logger, level: :info
+
+config :assoc,
+  ecto_repos: [Assoc.Test.Repo]
+
+config :assoc, Assoc.Test.Repo,
+  username: System.get_env("ASSOC_TEST_POSTGRES_USER"),
+  password: System.get_env("ASSOC_TEST_POSTGRES_PASS"),
+  database: System.get_env("ASSOC_TEST_POSTGRES_DB"),
+  hostname: System.get_env("ASSOC_TEST_POSTGRES_HOST"),
+  pool: Ecto.Adapters.SQL.Sandbox

lib/assoc.ex

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+defmodule Assoc do
+  @moduledoc """
+  """
+end

lib/assoc/schema.ex

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+defmodule Assoc.Schema do
+  @moduledoc """
+  ## Usage
+
+  ```
+  defmodule MyApp.User do
+    use MyApp.Schema
+    use Assoc.Schema, repo: MyApp.Repo
+
+    schema "users" do
+      field :email, :string
+      field :name, :string
+      has_many :user_roles, MyApp.UserRole, on_delete: :delete_all, on_replace: :delete
+      timestamps()
+    end
+
+    def updatable_associations, do: [
+      user_roles: MyApp.UserRole
+    ]
+
+    def changeset(struct, params \\ %{}) do
+      struct
+      |> cast(params, [:email, :name])
+      |> validate_required([:email])
+    end
+  end
+  ```
+
+  Key points:
+
+  - The `use Assoc.Schema` line should come after `use MyApp.Schema`.
+  - Pass the app's Repo into `use Assoc.Schema, repo: MyApp.Repo`
+  - Define a `updatable_associations` function. For each updatable association:
+    - The `key` should be the association name
+    - The `value` should be the association schema module
+  - The standard `changeset` function does not change.
+    - Include all the standard code for updating struct values (e.g. name, email) in `changeset`
+    - The library will create and use a separate `associations_changeset` to manage the associations
+  """
+
+  @callback updatable_associations :: List.t
+
+  defmacro __using__(repo: repo) do
+    quote do
+      @doc """
+      Preload all schema associations.
+
+      ## Usage
+
+      ```
+      MyApp.User.preload_all(user)
+      ```
+
+      ## Implementation
+
+      Builds a list of keys with `Ecto.Association.NotLoaded` values. Then
+      feeds the list into `Repo.preload`.
+      """
+      def preload_all(struct) do
+        keys = struct
+          |> Map.from_struct
+          |> Enum.reduce([], fn ({key, value}, acc) ->
+            case value do
+              %Ecto.Association.NotLoaded{} -> [key|acc]
+              _ -> acc
+            end
+          end)
+
+        unquote(repo).preload(struct, keys)
+      end
+
+      @doc """
+      Update associations defined in `updatable_associations/0` callback.
+      """
+      def associations_changeset(struct, params \\ %{}) do
+        struct = preload_associations(struct, updatable_associations())
+        params = include_existing_associations(struct, params)
+
+        struct
+        |> cast(params, [])
+        |> put_associations(updatable_associations(), params)
+      end
+
+      @doc """
+      Preload selected schema associations.
+      """
+      def preload_associations(struct, associations) do
+        associations = case Keyword.keyword?(associations) do
+          true -> Keyword.keys(associations)
+          false -> associations
+        end
+
+        unquote(repo).preload(struct, associations)
+      end
+
+      # Include existing associations in params by merging params into preload struct
+      defp include_existing_associations(struct, params) do
+        struct
+        |> Map.from_struct
+        |> Map.merge(params)
+      end
+
+      # Dynamically adds `put_assoc` calls to changeset
+      defp put_associations(changeset, associations, params) do
+        Enum.reduce(associations, changeset, fn ({key, _}, acc) ->
+          value = params
+            |> Assoc.Util.keys_to_atoms()
+            |> Map.get(key, :omitted)
+
+          case value do
+            :omitted -> acc
+            value -> put_assoc(acc, key, value)
+          end
+        end)
+      end
+    end
+  end
+end