Setting Property as Required in Godot

Props

Props are custom attributes registered on a component by declaring it in the list of props a component accepts:

<!-- MyComponent.vue -->
<script setup>
defineProps(['title'])
</script>
 
<template>
  <h4>{{ title }}</h4>
</template>

defineProps is only available inside <script setup>, and the declared props are automatically exposed to the template.
We can also access those props in code:

const props = defineProps(['title'])
console.log(props.title)

Passing the data to a registered prop is done through a custom attribute:

<MyComponent title="My journey with Vue" />
<MyComponent title="Blogging with Vue" />
<MyComponent title="Why Vue is so fun" />

You can also render a component for each of the props in an array:

const posts = ref([
  { id: 1, title: 'My journey with Vue' },
  { id: 2, title: 'Blogging with Vue' },
  { id: 3, title: 'Why Vue is so fun' }
])

<MyComponent
  v-for="post in posts"
  :key="post.id"
  :title="post.title"
 />

As of now (25/3/2024) there’s no way to make a property required in a strict sense.

A workaround has been proposed to set a configuration warning:

func _get_configuration_warning() -> String:
    if some_exported_value == 0:
        return "some_exported_value needs a value different than 0."
 
    return ""

But I haven’t had much luck with it myself.