lib/mv/authorization/permission_sets.ex

@@ -158,8 +158,9 @@ defmodule Mv.Authorization.PermissionSets do
         "/users/:id",
         "/users/:id/edit",
         "/users/:id/show/edit",
-        # Member list
+        # Member list and CSV export
         "/members",
+        "/members/export.csv",
         # Member detail
         "/members/:id",
         # Custom field values overview
@@ -208,6 +209,7 @@ defmodule Mv.Authorization.PermissionSets do
         "/users/:id/edit",
         "/users/:id/show/edit",
         "/members",
+        "/members/export.csv",
         # Create member
         "/members/new",
         "/members/:id",

lib/mv/membership/custom_field_value_formatter.ex

@@ -0,0 +1,55 @@
+defmodule Mv.Membership.CustomFieldValueFormatter do
+  @moduledoc """
+  Neutral formatter for custom field values (e.g. CSV export).
+
+  Same logic as the member overview Formatter but without Gettext or web helpers,
+  so it can be used from the Membership context. For boolean: "Yes"/"No";
+  for date: European format (dd.mm.yyyy).
+  """
+  @doc """
+  Formats a custom field value for plain text (e.g. CSV).
+
+  Handles nil, Ash.Union, JSONB map, and direct values. Uses custom_field.value_type
+  for typing. Boolean -> "Yes"/"No", Date -> dd.mm.yyyy.
+  """
+  def format_custom_field_value(nil, _custom_field), do: ""
+
+  def format_custom_field_value(%Ash.Union{value: value, type: type}, custom_field) do
+    format_value_by_type(value, type, custom_field)
+  end
+
+  def format_custom_field_value(value, custom_field) when is_map(value) do
+    type = Map.get(value, "type") || Map.get(value, "_union_type")
+    val = Map.get(value, "value") || Map.get(value, "_union_value")
+    format_value_by_type(val, type, custom_field)
+  end
+
+  def format_custom_field_value(value, custom_field) do
+    format_value_by_type(value, custom_field.value_type, custom_field)
+  end
+
+  defp format_value_by_type(value, :string, _), do: to_string(value)
+  defp format_value_by_type(value, :integer, _), do: to_string(value)
+
+  defp format_value_by_type(value, type, _) when type in [:string, :email] and is_binary(value) do
+    if String.trim(value) == "", do: "", else: value
+  end
+
+  defp format_value_by_type(value, :email, _), do: to_string(value)
+  defp format_value_by_type(value, :boolean, _) when value == true, do: "Yes"
+  defp format_value_by_type(value, :boolean, _) when value == false, do: "No"
+  defp format_value_by_type(value, :boolean, _), do: to_string(value)
+
+  defp format_value_by_type(%Date{} = date, :date, _) do
+    Calendar.strftime(date, "%d.%m.%Y")
+  end
+
+  defp format_value_by_type(value, :date, _) when is_binary(value) do
+    case Date.from_iso8601(value) do
+      {:ok, date} -> Calendar.strftime(date, "%d.%m.%Y")
+      _ -> value
+    end
+  end
+
+  defp format_value_by_type(value, _type, _), do: to_string(value)
+end

lib/mv/membership/members_csv.ex

@@ -0,0 +1,91 @@
+defmodule Mv.Membership.MembersCSV do
+  @moduledoc """
+  Exports members to CSV (RFC 4180) as iodata.
+
+  Uses NimbleCSV.RFC4180 for encoding. Member fields are formatted as strings;
+  custom field values use the same formatting logic as the member overview (neutral formatter).
+  Column order for custom fields follows the key order of the `custom_fields_by_id` map.
+  """
+  alias Mv.Membership.CustomFieldValueFormatter
+  alias NimbleCSV.RFC4180
+
+  @doc """
+  Exports a list of members to CSV iodata.
+
+  - `members` - List of member structs (with optional `custom_field_values` loaded)
+  - `member_fields` - List of member field names (strings, e.g. `["first_name", "email"]`)
+  - `custom_fields_by_id` - Map of custom_field_id => %CustomField{}. Key order defines column order.
+
+  Returns iodata suitable for `IO.iodata_to_binary/1` or sending as response body.
+  """
+  @spec export(
+          [struct()],
+          [String.t()],
+          %{optional(String.t() | Ecto.UUID.t()) => struct()}
+        ) :: iodata()
+  def export(members, member_fields, custom_fields_by_id) when is_list(members) do
+    custom_entries = custom_field_entries(custom_fields_by_id)
+    header = build_header(member_fields, custom_entries)
+    rows = Enum.map(members, &build_row(&1, member_fields, custom_entries))
+    RFC4180.dump_to_iodata([header | rows])
+  end
+
+  defp custom_field_entries(by_id) when is_map(by_id) do
+    Enum.map(by_id, fn {id, cf} -> {to_string(id), cf} end)
+  end
+
+  defp build_header(member_fields, custom_entries) do
+    member_headers = member_fields
+    custom_headers = Enum.map(custom_entries, fn {_id, cf} -> cf.name end)
+    member_headers ++ custom_headers
+  end
+
+  defp build_row(member, member_fields, custom_entries) do
+    member_cells = Enum.map(member_fields, &format_member_field(member, &1))
+
+    custom_cells =
+      Enum.map(custom_entries, fn {id, cf} -> format_custom_field(member, id, cf) end)
+
+    member_cells ++ custom_cells
+  end
+
+  defp format_member_field(member, field_name) do
+    key = member_field_key(field_name)
+    value = Map.get(member, key)
+    format_member_value(value)
+  end
+
+  defp member_field_key(field_name) when is_binary(field_name) do
+    try do
+      String.to_existing_atom(field_name)
+    rescue
+      ArgumentError -> field_name
+    end
+  end
+
+  defp format_member_value(nil), do: ""
+  defp format_member_value(true), do: "true"
+  defp format_member_value(false), do: "false"
+  defp format_member_value(%Date{} = d), do: Date.to_iso8601(d)
+  defp format_member_value(%DateTime{} = dt), do: DateTime.to_iso8601(dt)
+  defp format_member_value(%NaiveDateTime{} = dt), do: NaiveDateTime.to_iso8601(dt)
+  defp format_member_value(value), do: to_string(value)
+
+  defp format_custom_field(member, custom_field_id, custom_field) do
+    cfv = find_custom_field_value(member, custom_field_id)
+
+    if cfv,
+      do: CustomFieldValueFormatter.format_custom_field_value(cfv.value, custom_field),
+      else: ""
+  end
+
+  defp find_custom_field_value(member, custom_field_id) do
+    values = Map.get(member, :custom_field_values) || []
+    id_str = to_string(custom_field_id)
+
+    Enum.find(values, fn cfv ->
+      to_string(cfv.custom_field_id) == id_str or
+        (Map.get(cfv, :custom_field) && to_string(cfv.custom_field.id) == id_str)
+    end)
+  end
+end

lib/mv_web/controllers/member_export_controller.ex

@@ -0,0 +1,291 @@
+defmodule MvWeb.MemberExportController do
+  @moduledoc """
+  Controller for CSV export of members.
+
+  POST /members/export.csv with form param "payload" (JSON string).
+  Same permission and actor context as the member overview; 403 if unauthorized.
+  """
+  use MvWeb, :controller
+
+  require Ash.Query
+  import Ash.Expr
+
+  alias Mv.Membership.Member
+  alias Mv.Membership.CustomField
+  alias Mv.Membership.MembersCSV
+  alias Mv.Authorization.Actor
+
+  @member_fields_allowlist Mv.Constants.member_fields() |> Enum.map(&Atom.to_string/1)
+  @custom_field_prefix Mv.Constants.custom_field_prefix()
+
+  def export(conn, params) do
+    actor = current_actor(conn)
+    if is_nil(actor), do: return_forbidden(conn)
+
+    case params["payload"] do
+      nil ->
+        conn
+        |> put_status(400)
+        |> put_resp_content_type("application/json")
+        |> json(%{error: "payload required"})
+
+      payload when is_binary(payload) ->
+        case Jason.decode(payload) do
+          {:ok, decoded} when is_map(decoded) ->
+            parsed = parse_and_validate(decoded)
+            run_export(conn, actor, parsed)
+
+          _ ->
+            conn
+            |> put_status(400)
+            |> put_resp_content_type("application/json")
+            |> json(%{error: "invalid JSON"})
+        end
+    end
+  end
+
+  defp current_actor(conn) do
+    conn.assigns[:current_user]
+    |> Actor.ensure_loaded()
+  end
+
+  defp return_forbidden(conn) do
+    conn
+    |> put_status(403)
+    |> put_resp_content_type("application/json")
+    |> json(%{error: "Forbidden"})
+    |> halt()
+  end
+
+  defp parse_and_validate(params) do
+    %{
+      selected_ids: filter_valid_uuids(extract_list(params, "selected_ids")),
+      member_fields: filter_allowed_member_fields(extract_list(params, "member_fields")),
+      custom_field_ids: filter_valid_uuids(extract_list(params, "custom_field_ids")),
+      query: extract_string(params, "query"),
+      sort_field: extract_string(params, "sort_field"),
+      sort_order: extract_sort_order(params)
+    }
+  end
+
+  defp extract_list(params, key) do
+    case Map.get(params, key) do
+      list when is_list(list) -> list
+      _ -> []
+    end
+  end
+
+  defp extract_string(params, key) do
+    case Map.get(params, key) do
+      s when is_binary(s) -> s
+      _ -> nil
+    end
+  end
+
+  defp extract_sort_order(params) do
+    case Map.get(params, "sort_order") do
+      "asc" -> "asc"
+      "desc" -> "desc"
+      _ -> nil
+    end
+  end
+
+  defp filter_allowed_member_fields(field_list) do
+    allowlist = MapSet.new(@member_fields_allowlist)
+
+    field_list
+    |> Enum.filter(fn field -> is_binary(field) and MapSet.member?(allowlist, field) end)
+    |> Enum.uniq()
+  end
+
+  defp filter_valid_uuids(id_list) when is_list(id_list) do
+    id_list
+    |> Enum.filter(fn id -> is_binary(id) and match?({:ok, _}, Ecto.UUID.cast(id)) end)
+    |> Enum.uniq()
+  end
+
+  defp run_export(conn, actor, parsed) do
+    with {:ok, custom_fields_by_id} <- load_custom_fields_by_id(parsed.custom_field_ids, actor),
+         {:ok, members} <- load_members_for_export(actor, parsed, custom_fields_by_id) do
+      csv_iodata = MembersCSV.export(members, parsed.member_fields, custom_fields_by_id)
+      filename = "members-#{Date.utc_today()}.csv"
+
+      send_download(
+        conn,
+        {:binary, IO.iodata_to_binary(csv_iodata)},
+        filename: filename,
+        content_type: "text/csv; charset=utf-8"
+      )
+    else
+      {:error, :forbidden} ->
+        return_forbidden(conn)
+    end
+  end
+
+  defp load_custom_fields_by_id([], _actor), do: {:ok, %{}}
+
+  defp load_custom_fields_by_id(custom_field_ids, actor) do
+    query =
+      CustomField
+      |> Ash.Query.filter(expr(id in ^custom_field_ids))
+      |> Ash.Query.select([:id, :name, :value_type])
+
+    case Ash.read(query, actor: actor) do
+      {:ok, custom_fields} ->
+        by_id = build_custom_fields_by_id(custom_field_ids, custom_fields)
+        {:ok, by_id}
+
+      {:error, %Ash.Error.Forbidden{}} ->
+        {:error, :forbidden}
+    end
+  end
+
+  defp build_custom_fields_by_id(custom_field_ids, custom_fields) do
+    Enum.reduce(custom_field_ids, %{}, fn id, acc ->
+      find_and_add_custom_field(acc, id, custom_fields)
+    end)
+  end
+
+  defp find_and_add_custom_field(acc, id, custom_fields) do
+    case Enum.find(custom_fields, fn cf -> to_string(cf.id) == to_string(id) end) do
+      nil -> acc
+      cf -> Map.put(acc, id, cf)
+    end
+  end
+
+  defp load_members_for_export(actor, parsed, custom_fields_by_id) do
+    select_fields = [:id] ++ Enum.map(parsed.member_fields, &String.to_existing_atom/1)
+
+    query =
+      Member
+      |> Ash.Query.new()
+      |> Ash.Query.select(select_fields)
+      |> load_custom_field_values_query(parsed.custom_field_ids)
+
+    query =
+      if parsed.selected_ids != [] do
+        Ash.Query.filter(query, expr(id in ^parsed.selected_ids))
+      else
+        query
+        |> apply_search_export(parsed.query)
+        |> then(fn q ->
+          {q, _sort_after_load} = maybe_sort_export(q, parsed.sort_field, parsed.sort_order)
+          q
+        end)
+      end
+
+    case Ash.read(query, actor: actor) do
+      {:ok, members} ->
+        members =
+          if parsed.selected_ids == [] and sort_after_load?(parsed.sort_field) do
+            sort_members_by_custom_field_export(
+              members,
+              parsed.sort_field,
+              parsed.sort_order,
+              Map.values(custom_fields_by_id)
+            )
+          else
+            # selected_ids != []: no sort. selected_ids == [] and DB sort: already in query.
+            members
+          end
+
+        {:ok, members}
+
+      {:error, %Ash.Error.Forbidden{}} ->
+        {:error, :forbidden}
+    end
+  end
+
+  defp load_custom_field_values_query(query, []), do: query
+
+  defp load_custom_field_values_query(query, custom_field_ids) do
+    cfv_query =
+      Mv.Membership.CustomFieldValue
+      |> Ash.Query.filter(expr(custom_field_id in ^custom_field_ids))
+      |> Ash.Query.load(custom_field: [:id, :name, :value_type])
+
+    Ash.Query.load(query, custom_field_values: cfv_query)
+  end
+
+  defp apply_search_export(query, nil), do: query
+  defp apply_search_export(query, ""), do: query
+
+  defp apply_search_export(query, q) when is_binary(q) do
+    if String.trim(q) != "" do
+      Member.fuzzy_search(query, %{query: q})
+    else
+      query
+    end
+  end
+
+  defp maybe_sort_export(query, nil, _order), do: {query, false}
+  defp maybe_sort_export(query, _field, nil), do: {query, false}
+
+  defp maybe_sort_export(query, field, order) when is_binary(field) do
+    if custom_field_sort?(field) do
+      {query, true}
+    else
+      field_atom = String.to_existing_atom(field)
+
+      if field_atom in (Mv.Constants.member_fields() -- [:notes]) do
+        {Ash.Query.sort(query, [{field_atom, String.to_existing_atom(order)}]), false}
+      else
+        {query, false}
+      end
+    end
+  rescue
+    ArgumentError -> {query, false}
+  end
+
+  defp sort_after_load?(field) when is_binary(field),
+    do: String.starts_with?(field, @custom_field_prefix)
+
+  defp sort_after_load?(_), do: false
+
+  defp sort_members_by_custom_field_export(members, _field, _order, _custom_fields)
+       when members == [],
+       do: []
+
+  defp sort_members_by_custom_field_export(members, field, order, custom_fields)
+       when is_binary(field) do
+    id_str = String.trim_leading(field, @custom_field_prefix)
+    custom_field = Enum.find(custom_fields, fn cf -> to_string(cf.id) == id_str end)
+    if is_nil(custom_field), do: members
+
+    extract_sort_val = fn member ->
+      cfv = find_cfv(member, custom_field)
+      if cfv, do: extract_sort_value(cfv.value, custom_field.value_type), else: nil
+    end
+
+    sorted =
+      members
+      |> Enum.sort_by(extract_sort_val, fn
+        nil, _ -> false
+        _, nil -> true
+        a, b -> if order == "desc", do: a >= b, else: a <= b
+      end)
+
+    if order == "desc", do: Enum.reverse(sorted), else: sorted
+  end
+
+  defp find_cfv(member, custom_field) do
+    (member.custom_field_values || [])
+    |> Enum.find(fn cfv ->
+      to_string(cfv.custom_field_id) == to_string(custom_field.id) or
+        (Map.get(cfv, :custom_field) &&
+           to_string(cfv.custom_field.id) == to_string(custom_field.id))
+    end)
+  end
+
+  defp extract_sort_value(%Ash.Union{value: value, type: type}, _),
+    do: extract_sort_value(value, type)
+
+  defp extract_sort_value(value, :string) when is_binary(value), do: value
+  defp extract_sort_value(value, :integer) when is_integer(value), do: value
+  defp extract_sort_value(value, :boolean) when is_boolean(value), do: value
+  defp extract_sort_value(%Date{} = d, :date), do: d
+  defp extract_sort_value(value, :email) when is_binary(value), do: value
+  defp extract_sort_value(value, _), do: to_string(value)
+
+  defp custom_field_sort?(field), do: String.starts_with?(field, @custom_field_prefix)
+end

lib/mv_web/live/member_live/index.ex

@@ -131,6 +131,7 @@ defmodule MvWeb.MemberLive.Index do
       )
       |> assign(:show_current_cycle, false)
       |> assign(:membership_fee_status_filter, nil)
+      |> assign_export_payload()
 
     # We call handle params to use the query from the URL
     {:ok, socket}
@@ -1729,5 +1730,36 @@ defmodule MvWeb.MemberLive.Index do
     |> assign(:selected_count, selected_count)
     |> assign(:any_selected?, any_selected?)
     |> assign(:mailto_bcc, mailto_bcc)
+    |> assign_export_payload()
   end
+
+  # Builds the export payload map and assigns :export_payload_json for the CSV export form.
+  # Called when selection, visible fields, query, or sort change so the form always has current data.
+  defp assign_export_payload(socket) do
+    payload = build_export_payload(socket)
+    assign(socket, :export_payload_json, Jason.encode!(payload))
+  end
+
+  defp build_export_payload(socket) do
+    member_fields_visible = socket.assigns[:member_fields_visible] || []
+    visible_custom_field_ids = socket.assigns[:visible_custom_field_ids] || []
+
+    %{
+      selected_ids: socket.assigns.selected_members |> MapSet.to_list(),
+      member_fields: Enum.map(member_fields_visible, &Atom.to_string/1),
+      custom_field_ids: visible_custom_field_ids,
+      query: socket.assigns[:query] || nil,
+      sort_field: export_sort_field(socket.assigns[:sort_field]),
+      sort_order: export_sort_order(socket.assigns[:sort_order])
+    }
+  end
+
+  defp export_sort_field(nil), do: nil
+  defp export_sort_field(f) when is_atom(f), do: Atom.to_string(f)
+  defp export_sort_field(f) when is_binary(f), do: f
+
+  defp export_sort_order(nil), do: nil
+  defp export_sort_order(:asc), do: "asc"
+  defp export_sort_order(:desc), do: "desc"
+  defp export_sort_order(o) when is_binary(o), do: o
 end

lib/mv_web/live/member_live/index.html.heex

@@ -2,6 +2,20 @@
   <.header>
     {gettext("Members")}
     <:actions>
+      <form method="post" action={~p"/members/export.csv"} target="_blank" class="inline">
+        <input type="hidden" name="_csrf_token" value={Plug.CSRFProtection.get_csrf_token()} />
+        <input type="hidden" name="payload" value={@export_payload_json} />
+        <button
+          type="submit"
+          class="btn btn-secondary gap-2"
+          aria-label={gettext("Export members to CSV")}
+        >
+          <.icon name="hero-arrow-down-tray" />
+          {gettext("Export to CSV")} ({if @selected_count == 0,
+            do: gettext("all"),
+            else: @selected_count})
+        </button>
+      </form>
       <.button
         class="secondary"
         id="copy-emails-btn"

lib/mv_web/router.ex

@@ -91,6 +91,7 @@ defmodule MvWeb.Router do
       # Import/Export (Admin only)
       live "/admin/import-export", ImportExportLive
 
+      post "/members/export.csv", MemberExportController, :export
       post "/set_locale", LocaleController, :set_locale
     end