discourse/app/assets/javascripts/admin/addon/routes/admin-customize-themes-edit.js

import I18n from "I18n";
import Route from "@ember/routing/route";
import { inject as service } from "@ember/service";

export default Route.extend({
  dialog: service(),

  model(params) {
    const all = this.modelFor("adminCustomizeThemes");
    const model = all.findBy("id", parseInt(params.theme_id, 10));
    return model
      ? {
          model,
          target: params.target,
          field_name: params.field_name,
        }
      : this.replaceWith("adminCustomizeThemes.index");
  },

  serialize(wrapper) {
    return {
      model: wrapper.model,
      target: wrapper.target || "common",
      field_name: wrapper.field_name || "scss",
      theme_id: wrapper.model.get("id"),
    };
  },

  setupController(controller, wrapper) {
    const fields = wrapper.model
      .get("fields")
      [wrapper.target].map((f) => f.name);
    if (wrapper.model.remote_theme && wrapper.model.remote_theme.is_git) {
      this.transitionTo("adminCustomizeThemes.index");
      return;
    }
    if (!fields.includes(wrapper.field_name)) {
      this.transitionTo(
        "adminCustomizeThemes.edit",
        wrapper.model.id,
        wrapper.target,
        fields[0]
      );
      return;
    }
    controller.set("model", wrapper.model);
    controller.setTargetName(wrapper.target || "common");
    controller.set("fieldName", wrapper.field_name || "scss");
    this.controllerFor("adminCustomizeThemes").set("editingTheme", true);
    this.set("shouldAlertUnsavedChanges", true);
  },

  actions: {
    willTransition(transition) {
      if (
        this.get("controller.model.changed") &&
        this.shouldAlertUnsavedChanges &&
        transition.intent.name !== this.routeName
      ) {
        transition.abort();

        this.dialog.confirm({
          message: I18n.t("admin.customize.theme.unsaved_changes_alert"),
          confirmButtonLabel: "admin.customize.theme.discard",
          cancelButtonLabel: "admin.customize.theme.stay",
          didConfirm: () => {
            this.set("shouldAlertUnsavedChanges", false);
            transition.retry();
          },
        });
      }
    },
  },
});