Extract query validation callback step to custom validator

lib/philomena/filters/filter.ex

@@ -1,9 +1,10 @@
 defmodule Philomena.Filters.Filter do
   use Ecto.Schema
   import Ecto.Changeset
+  import PhilomenaQuery.Ecto.QueryValidator
 
   alias Philomena.Schema.TagList
-  alias Philomena.Schema.Search
+  alias Philomena.Images.Query
   alias Philomena.Users.User
   alias Philomena.Repo
 
@@ -48,8 +49,8 @@ defmodule Philomena.Filters.Filter do
     |> validate_required([:name])
     |> validate_my_downvotes(:spoilered_complex_str)
     |> validate_my_downvotes(:hidden_complex_str)
-    |> Search.validate_search(:spoilered_complex_str, user)
-    |> Search.validate_search(:hidden_complex_str, user)
+    |> validate_query(:spoilered_complex_str, &Query.compile(&1, user: user))
+    |> validate_query(:hidden_complex_str, &Query.compile(&1, user: user))
     |> unsafe_validate_unique([:user_id, :name], Repo)
   end
 

lib/philomena/schema/search.ex

@@ -1,18 +0,0 @@
-defmodule Philomena.Schema.Search do
-  alias Philomena.Images.Query
-  alias PhilomenaQuery.Parse.String
-  import Ecto.Changeset
-
-  def validate_search(changeset, field, user, watched \\ false) do
-    query = changeset |> get_field(field) |> String.normalize()
-    output = Query.compile(query, user: user, watch: watched)
-
-    case output do
-      {:ok, _} ->
-        changeset
-
-      _ ->
-        add_error(changeset, field, "is invalid")
-    end
-  end
-end

lib/philomena/users/user.ex

@@ -4,10 +4,11 @@ defmodule Philomena.Users.User do
 
   use Ecto.Schema
   import Ecto.Changeset
+  import PhilomenaQuery.Ecto.QueryValidator
 
   alias Philomena.Schema.TagList
-  alias Philomena.Schema.Search
 
+  alias Philomena.Images.Query
   alias Philomena.Filters.Filter
   alias Philomena.ArtistLinks.ArtistLink
   alias Philomena.Badges
@@ -354,8 +355,8 @@ defmodule Philomena.Users.User do
     |> validate_inclusion(:images_per_page, 1..50)
     |> validate_inclusion(:comments_per_page, 1..100)
     |> validate_inclusion(:scale_large_images, ["false", "partscaled", "true"])
-    |> Search.validate_search(:watched_images_query_str, user, true)
-    |> Search.validate_search(:watched_images_exclude_str, user, true)
+    |> validate_query(:watched_images_query_str, &Query.compile(&1, user: user, watch: true))
+    |> validate_query(:watched_images_exclude_str, &Query.compile(&1, user: user, watch: true))
   end
 
   def description_changeset(user, attrs) do

lib/philomena_query/ecto/query_validator.ex

@@ -0,0 +1,69 @@
+defmodule PhilomenaQuery.Ecto.QueryValidator do
+  @moduledoc """
+  Query string validation for Ecto.
+
+  It enables the following usage pattern by taking a fn of the compiler:
+
+      defmodule Filter do
+        import PhilomenaQuery.Ecto.QueryValidator
+
+        # ...
+
+        def changeset(filter, attrs, user) do
+          filter
+          |> cast(attrs, [:complex])
+          |> validate_required([:complex])
+          |> validate_query([:complex], with: &Query.compile(&1, user: user))
+        end
+      end
+
+  """
+
+  import Ecto.Changeset
+  alias PhilomenaQuery.Parse.String
+
+  @doc """
+  Validates a query string using the provided attribute(s) and compiler.
+
+  Returns the changeset as-is, or with an `"is invalid"` error added to validated field.
+
+  ## Examples
+
+      # With single attribute
+      filter
+      |> cast(attrs, [:complex])
+      |> validate_query(:complex, &Query.compile(&1, user: user))
+
+      # With list of attributes
+      filter
+      |> cast(attrs, [:spoilered_complex, :hidden_complex])
+      |> validate_query([:spoilered_complex, :hidden_complex], &Query.compile(&1, user: user))
+
+  """
+  def validate_query(changeset, attr_or_attr_list, callback)
+
+  def validate_query(changeset, attr_list, callback) when is_list(attr_list) do
+    Enum.reduce(attr_list, changeset, fn attr, changeset ->
+      validate_query(changeset, attr, callback)
+    end)
+  end
+
+  def validate_query(changeset, attr, callback) do
+    if changed?(changeset, attr) do
+      validate_assuming_changed(changeset, attr, callback)
+    else
+      changeset
+    end
+  end
+
+  defp validate_assuming_changed(changeset, attr, callback) do
+    with value when is_binary(value) <- fetch_change!(changeset, attr) || "",
+         value <- String.normalize(value),
+         {:ok, _} <- callback.(value) do
+      changeset
+    else
+      _ ->
+        add_error(changeset, attr, "is invalid")
+    end
+  end
+end