Improve hashtag search with multi word queries

changelog.d/hashtag-search.change

@@ -0,0 +1 @@
+Hashtag searches return real results based on words in your query

lib/pleroma/hashtag.ex

@@ -135,18 +135,28 @@ defmodule Pleroma.Hashtag do
     limit = Keyword.get(options, :limit, 20)
     offset = Keyword.get(options, :offset, 0)
 
-    query
-    |> String.downcase()
-    |> String.trim()
-    |> then(fn search_term ->
+    search_terms =
+      query
+      |> String.downcase()
+      |> String.trim()
+      |> String.split(~r/\s+/)
+      |> Enum.filter(&(&1 != ""))
+
+    if Enum.empty?(search_terms) do
+      []
+    else
+      # Use PostgreSQL's ANY operator with array for efficient multi-term search
+      # This is much more efficient than multiple OR clauses
+      search_patterns = Enum.map(search_terms, &"%#{&1}%")
+
       from(ht in Hashtag,
-        where: fragment("LOWER(?) LIKE ?", ht.name, ^"%#{search_term}%"),
+        where: fragment("LOWER(?) LIKE ANY(?)", ht.name, ^search_patterns),
         order_by: [asc: ht.name],
         limit: ^limit,
         offset: ^offset
       )
       |> Repo.all()
       |> Enum.map(& &1.name)
-    end)
+    end
   end
 end

test/pleroma/hashtag_test.exs

@@ -38,6 +38,35 @@ defmodule Pleroma.HashtagTest do
       assert results == []
     end
 
+    test "searches hashtags by multiple words in query" do
+      # Create some hashtags
+      {:ok, _} = Hashtag.get_or_create_by_name("computer")
+      {:ok, _} = Hashtag.get_or_create_by_name("laptop")
+      {:ok, _} = Hashtag.get_or_create_by_name("desktop")
+      {:ok, _} = Hashtag.get_or_create_by_name("phone")
+
+      # Search for "new computer" - should return "computer"
+      results = Hashtag.search("new computer")
+      assert "computer" in results
+      refute "laptop" in results
+      refute "desktop" in results
+      refute "phone" in results
+
+      # Search for "computer laptop" - should return both
+      results = Hashtag.search("computer laptop")
+      assert "computer" in results
+      assert "laptop" in results
+      refute "desktop" in results
+      refute "phone" in results
+
+      # Search for "new phone" - should return "phone"
+      results = Hashtag.search("new phone")
+      assert "phone" in results
+      refute "computer" in results
+      refute "laptop" in results
+      refute "desktop" in results
+    end
+
     test "supports pagination" do
       {:ok, _} = Hashtag.get_or_create_by_name("alpha")
       {:ok, _} = Hashtag.get_or_create_by_name("beta")
@@ -50,5 +79,20 @@ defmodule Pleroma.HashtagTest do
       results = Hashtag.search("a", limit: 2, offset: 1)
       assert length(results) == 2
     end
+
+    test "handles many search terms efficiently" do
+      # Create hashtags
+      {:ok, _} = Hashtag.get_or_create_by_name("computer")
+      {:ok, _} = Hashtag.get_or_create_by_name("laptop")
+      {:ok, _} = Hashtag.get_or_create_by_name("phone")
+      {:ok, _} = Hashtag.get_or_create_by_name("tablet")
+
+      # Search with many terms - should be efficient with PostgreSQL ANY operator
+      results = Hashtag.search("new fast computer laptop phone tablet device")
+      assert "computer" in results
+      assert "laptop" in results
+      assert "phone" in results
+      assert "tablet" in results
+    end
   end
 end

test/pleroma/web/mastodon_api/controllers/search_controller_test.exs

@@ -139,6 +139,37 @@ defmodule Pleroma.Web.MastodonAPI.SearchControllerTest do
       assert results["hashtags"] == []
     end
 
+    test "searches hashtags by multiple words in query", %{conn: conn} do
+      user = insert(:user)
+
+      {:ok, _activity1} = CommonAPI.post(user, %{status: "This is my new #computer"})
+      {:ok, _activity2} = CommonAPI.post(user, %{status: "Check out this #laptop"})
+      {:ok, _activity3} = CommonAPI.post(user, %{status: "My #desktop setup"})
+      {:ok, _activity4} = CommonAPI.post(user, %{status: "New #phone arrived"})
+
+      results =
+        conn
+        |> get("/api/v2/search?#{URI.encode_query(%{q: "new computer"})}")
+        |> json_response_and_validate_schema(200)
+
+      hashtag_names = Enum.map(results["hashtags"], & &1["name"])
+      assert "computer" in hashtag_names
+      refute "laptop" in hashtag_names
+      refute "desktop" in hashtag_names
+      refute "phone" in hashtag_names
+
+      results =
+        conn
+        |> get("/api/v2/search?#{URI.encode_query(%{q: "computer laptop"})}")
+        |> json_response_and_validate_schema(200)
+
+      hashtag_names = Enum.map(results["hashtags"], & &1["name"])
+      assert "computer" in hashtag_names
+      assert "laptop" in hashtag_names
+      refute "desktop" in hashtag_names
+      refute "phone" in hashtag_names
+    end
+
     test "supports pagination of hashtags search results", %{conn: conn} do
       user = insert(:user)