VeeValidate with Yup: input type="number" value is converted to string on submit - vue.js

Question

I use VeeValidate and Yup for form validation and don't know why my input field with type="number" is converted to string on submit.
When I input 78 and submit the form the output of the console.log in the onSubmit(values) function is the following:
values: {
prioritaet: "78"
}
Am I doing something wrong here or is this the normal behavior of VeeValidate and Yup? I would like to have a number instead of a string after submit.
My code looks like this:
<template>
<div class="container m-3">
<div class="row bg-primary align-items-center py-2">
<div class="col">
<h3 class="text-light mb-0">Format {{ this.action }}</h3>
</div>
<div class="col-auto">
<h5 class="text-light mb-0">{{ this.formatTitle }}</h5>
</div>
</div>
<Form #submit="onSubmit" :validation-schema="formatSchema" v-slot="{ errors }" ref="formatForm">
<div class="row mt-4">
<div class="col">
<h5>Formatdaten</h5>
</div>
</div>
<div class="row mb-2">
<div class="col-4">
<label for="prioritaet-input">Priorität: </label>
</div>
<div class="col">
<Field type="number" name="prioritaet" id="prioritaet-input" class="w-100" />
</div>
</div>
<div class="row justify-content-end">
<div class="col-auto me-auto">
<button class="btn btn-outline-primary">Änderungen übernehmen</button>
</div>
<div class="col-auto">
<button class="btn btn-outline-primary">Abbrechen</button>
</div>
<div class="col-auto">
<button type="sumbit" class="btn btn-outline-primary">Speichern</button>
</div>
</div>
<div class="row mt-4">
<template v-if="Object.keys(errors).length">
<span class="text-danger" v-for="(message, field) in errors" :key="field">{{ message }}</span>
</template>
</div>
</Form>
</div>
</template>
<script>
import { Form, Field } from "vee-validate";
import deLocale from "../assets/yup-localization.js";
import * as Yup from "yup";
import { markRaw } from "vue";
import { mapActions, mapState } from "vuex";
Yup.setLocale(deLocale);
export default {
name: "FormatBearbeitungsSchirm",
props: ["material_id"],
data() {
let action = "neu";
let formatTitle = "Format neu";
let formatSchema = markRaw(Yup.object().shape({
prioritaet: Yup.number().min(1).max(100).integer().label("Priorität"),
}));
return { formatSchema, action, formatTitle };
},
created() {
},
components: {
Form,
Field,
},
methods: {
onSubmit(values) {
console.log("values", values);
},
},
};
</script>

Answer 1

It looks like there is currently no support for specifying the .number modifier on the internal field model value of <Field>, so the emitted form values would always contain a string for number-type fields.
One workaround is to convert the value in the template, updating <Form>'s values slot prop in <Field>'s update:modelValue event:
<Form #submit="onSubmit" v-slot="{ values }">
<Field 👆
type="number"
name="prioritaet" 👇
#update:modelValue="values.prioritaet = Number(values.prioritaet)"
/>
<button>Submit</button>
</Form>
demo
Another simple workaround is to convert the property inside onSubmit before using it:
export default {
onSubmit(values) {
values.prioritaet = Number(values.prioritaet)
// use values here...
}
}

Answer 2

You must use the .number modifier.
You can read about it here
If you want user input to be automatically typecast as a Number, you can add the number modifier to your v-model managed inputs:
const app = new Vue({
el: "#app",
data: () => ({
mynumber1: undefined,
mynumber2: undefined
}),
methods: {
submit() {
console.log(typeof this.mynumber1, this.mynumber1)
console.log(typeof this.mynumber2, this.mynumber2)
}
}
})
<script src="https://cdn.jsdelivr.net/npm/vue#2.6.14/dist/vue.js"></script>
<div id="app">
<form>
<!-- number modifier -->
<input type="number" v-model.number="mynumber1" placeholder="Type here" />
<!-- no modifier -->
<input type="number" v-model="mynumber2" placeholder="Type here" />
<input type="button" #click="submit" value="submit" />
</form>
</div>