How can I trigger an InertiaUI modal from a Laravel controller in my Vue3 app?

This error usually indicates that the Inertia modal system isn’t fully set up when you try to open the modal via a server response. In other words, the modal “store” or the controller that manages modal state (often provided by the Inertia modal plugin) isn’t available on the initial page load when you return a full page render from your Laravel controller.

Below are some steps to help troubleshoot and resolve the issue:

1. Ensure Plugin Initialization
   Verify that you’ve correctly registered the InertiaUI modal plugin in your Vue3 app. Usually this means importing and installing the plugin in your main.js (or main.ts) file and making sure the modal container component is rendered in your layout. For example:

   JSCopied
   // main.js
   import { createApp, h } from 'vue'
   import { createInertiaApp } from '@inertiajs/inertia-vue3'
   import InertiaModal from 'inertia-modal' // or the correct import based on the docs
   
   createInertiaApp({
     resolve: name => require(`./Pages/${name}`),
     setup({ el, App, props, plugin }) {
       const app = createApp({ render: () => h(App, props) })
       app.use(plugin)
       app.use(InertiaModal) // make sure the modal plugin is registered
       app.mount(el)
     },
   })

   Also, ensure that your layout includes the modal container as specified in the InertiaUI modal docs. For instance, you might need to add something like <InertiaModal /> somewhere in your root (or layout) component.

2. Triggering the Modal from the Server
   Inertia modals are primarily designed to be controlled on the client side. When you flash modal data from your Laravel controller (or return a page with modal props), you need to make sure that the client-side code recognizes and processes that data correctly. For example, if you use:

   PHPCopied
   session()->flash('modal', [
     'component' => 'UserGameShow',
     'props' => [
       'game' => $game,
       'scores' => $scores,
     ]
   ]);

   make sure your Vue application (or a dedicated modal layout) watches for the modal prop or session value and then triggers the modal. Without that, the modal state might be undefined, hence the error you see.

3. Check Timing and DOM Presence
   The error message—reading shouldRender on an undefined property—often points to timing issues. Ensure that when your page renders (coming from Inertia::render in your controller), the modal target (or dedicated container) is already in the DOM. If the modal container isn’t mounted yet, the modal plugin may try to access undefined values.

4. Alternative Approach
   If triggering the modal from the controller continues to be problematic, a common workaround is to have the controller return a prop (for example, showModal: true) along with your page props. Then, inside your Vue component, watch that prop and use the client-side modal methods to open the modal. For example:

   VUECopied
   <script setup>
   import { ref, watch } from 'vue'
   const props = defineProps({
     showModal: Boolean,
     game: Object,
     scores: Array,
     gameId: Number,
   })
   
   const modalOpen = ref(false)
   
   // Trigger modal open when showModal becomes true.
   watch(
     () => props.showModal,
     (newValue) => {
       if (newValue) {
         modalOpen.value = true
       }
     },
     { immediate: true }
   )
   </script>
   
   <template>
     <Modal v-if="modalOpen">
       <!-- modal content here -->
       <p>{{ game.title }}</p>
     </Modal>
   </template>

   Then in your Laravel controller, you can return:

   PHPCopied
   public function store() {
       // code...
       return Inertia::render('UserGameShow', [
           'game' => $game,
           'scores' => $scores,
           'gameId' => $game->id,
           'showModal' => true,
       ]);
   }

By ensuring the modal system is initialized correctly and that you’re triggering the modal on the client side (after the page has mounted), you should be able to avoid the undefined state that leads to the error “Cannot read properties of undefined (reading 'shouldRender')”.