From d41d13d1220d659545d80a2b3052ebe380c920c8 Mon Sep 17 00:00:00 2001
From: Moritz <moritz.m@local-it.org>
Date: Tue, 24 Feb 2026 01:06:41 +0100
Subject: [PATCH] fix(members): restore column visibility from URL on reload

Read 'fields' from URI when conn.params has no query (e.g. full page load).
When ?fields=... is present use URL-only selection so columns are not
merged with global settings. Fall back to session+global when URL has
only invalid field names.
---
 lib/mv_web/live/member_live/index.ex          | 82 +++++++++++++++----
 .../member_live/index/field_visibility.ex     | 19 +++++
 2 files changed, 86 insertions(+), 15 deletions(-)

diff --git a/lib/mv_web/live/member_live/index.ex b/lib/mv_web/live/member_live/index.ex
index e7c0fd7..889a818 100644
--- a/lib/mv_web/live/member_live/index.ex
+++ b/lib/mv_web/live/member_live/index.ex
@@ -615,7 +615,9 @@ defmodule MvWeb.MemberLive.Index do
   # -----------------------------------------------------------------
 
   @impl true
-  def handle_params(params, _url, socket) do
+  def handle_params(params, url, socket) do
+    url = url || request_url_from_socket(socket)
+    params = merge_fields_param_from_uri(params, url)
     prev_sig = build_signature(socket)
 
     fields_in_url? =
@@ -625,20 +627,7 @@ defmodule MvWeb.MemberLive.Index do
       end
 
     url_selection = FieldSelection.parse_from_url(params)
-
-    merged_selection =
-      FieldSelection.merge_sources(
-        url_selection,
-        socket.assigns.user_field_selection,
-        %{}
-      )
-
-    final_selection =
-      FieldVisibility.merge_with_global_settings(
-        merged_selection,
-        socket.assigns.settings,
-        socket.assigns.all_custom_fields
-      )
+    final_selection = compute_final_field_selection(fields_in_url?, url_selection, socket)
 
     visible_member_fields =
       final_selection
@@ -828,6 +817,69 @@ defmodule MvWeb.MemberLive.Index do
     add_boolean_filters(base_params, boolean_filters)
   end
 
+  defp compute_final_field_selection(true, url_selection, socket) do
+    only_url =
+      FieldVisibility.selection_from_url_only(url_selection, socket.assigns.all_custom_fields)
+
+    visible = FieldVisibility.get_visible_member_fields(only_url)
+
+    if visible == [] do
+      # URL had only invalid field names; fall back to session + global.
+      compute_final_field_selection(false, url_selection, socket)
+    else
+      only_url
+    end
+  end
+
+  defp compute_final_field_selection(false, url_selection, socket) do
+    merged =
+      FieldSelection.merge_sources(
+        url_selection,
+        socket.assigns.user_field_selection,
+        %{}
+      )
+
+    FieldVisibility.merge_with_global_settings(
+      merged,
+      socket.assigns.settings,
+      socket.assigns.all_custom_fields
+    )
+  end
+
+  # On full page load conn.params has no query string; read "fields" from URI so column visibility is restored.
+  defp request_url_from_socket(socket) do
+    case socket.private[:connect_info] do
+      %Plug.Conn{} = conn -> Plug.Conn.request_url(conn)
+      _ -> nil
+    end
+  end
+
+  defp merge_fields_param_from_uri(params, nil), do: params
+
+  defp merge_fields_param_from_uri(params, %URI{query: query}) when is_binary(query) do
+    case URI.decode_query(query)["fields"] do
+      nil -> params
+      value -> Map.put(params, "fields", value)
+    end
+  end
+
+  defp merge_fields_param_from_uri(params, %URI{}), do: params
+
+  defp merge_fields_param_from_uri(params, url) when is_binary(url) do
+    case URI.parse(url).query do
+      nil ->
+        params
+
+      q ->
+        case URI.decode_query(q)["fields"] do
+          nil -> params
+          value -> Map.put(params, "fields", value)
+        end
+    end
+  end
+
+  defp merge_fields_param_from_uri(params, _), do: params
+
   defp build_base_params(query, sort_field, sort_order) do
     %{
       "query" => query || "",
diff --git a/lib/mv_web/live/member_live/index/field_visibility.ex b/lib/mv_web/live/member_live/index/field_visibility.ex
index 7b54bba..df20d25 100644
--- a/lib/mv_web/live/member_live/index/field_visibility.ex
+++ b/lib/mv_web/live/member_live/index/field_visibility.ex
@@ -64,6 +64,25 @@ defmodule MvWeb.MemberLive.Index.FieldVisibility do
     member_fields ++ custom_field_names
   end
 
+  @doc """
+  Builds field selection from URL only: fields in `url_selection` are visible, all others false.
+  Use when `?fields=...` is in the URL so column visibility is not merged with global settings.
+  """
+  @spec selection_from_url_only(%{String.t() => boolean()}, [struct()]) :: %{
+          String.t() => boolean()
+        }
+  def selection_from_url_only(url_selection, custom_fields) when is_map(url_selection) do
+    all_fields = get_all_available_fields(custom_fields)
+
+    Enum.reduce(all_fields, %{}, fn field, acc ->
+      field_string = field_to_string(field)
+      visible = Map.get(url_selection, field_string, false)
+      Map.put(acc, field_string, visible)
+    end)
+  end
+
+  def selection_from_url_only(_, _), do: %{}
+
   @doc """
   Merges user field selection with global settings.