Damn, I feel dumb to not have read the documentation properly, and creating a post not related to Quasar at all…
Thanks.

Thanks, it works that way, but in the vuelidate doc, about the $dirty property, it’s written that it is set automatically when writing to $model value.
In my case, it’s not set automatically.

Hello, I have issue with vuelidate (0.7.4) integration with last version of Quasar.

I added vuelidate in boot folder.

My component :

<template>
  <q-page class="flex flex-center">
    <div class="q-pa-md" style="max-width: 400px">

      <q-card class="q-pa-md">
        <q-form
          @submit="onSubmit"
          class="q-gutter-md"
        >

          {{$v.form.username}}
          <p v-if="error" class="q-pa-sm text-white rounded-borders bg-negative">{{ error }}</p>
          <q-input
            filled
            v-model.trim.lazy="form.username"
            :disabled="loading"
            label="Your login *"
            hint="Nom d'utilisateur ou adresse e-mail"
            :error="!this.$v.form.username.$error"
            error-message="Required"
          >
            <template v-slot:prepend>
              <q-icon name="person"/>
            </template>
          </q-input>


          <q-input
            filled
            type="password"
            :disabled="loading"
            v-model.trim="form.password"
            label="Votre mot de passe *"
            :error="!this.$v.form.password.$error"
            error-message="Required"
          >
            <template v-slot:prepend>
              <q-icon name="vpn_key"/>
            </template>
          </q-input>

          <div>
            <q-btn type="submit" color="primary" :disabled="this.loading">
              <q-spinner v-if="this.loading"></q-spinner>
              Log in
            </q-btn>
          </div>
        </q-form>
      </q-card>

    </div>
  </q-page>
</template>

<script>
  import {required} from 'vuelidate/lib/validators'

  export default {
    name: 'Login',
    data: function () {
      return {
        form: {
          username: '',
          password: ''
        },
        loading: false,
        error: ''
      }
    },
    validations: {
      form: {
        username: {required},
        password: {required}
      }
    },

    methods: {
      async onSubmit() {
       ....
      }
    }
  }
</script>

<style>
</style>

My issue is that all value from $v state are not update.
model, $invalid and required are updated, but $error and $dirty are always false.

Here is $v value when login field is empty :

{ 
"required": false, 
"$model": "",
"$invalid": true, 
"$dirty": false, 
"$anyDirty": false, 
"$error": false, 
"$anyError": false, 
"$pending": false, 
"$params": { "required": { "type": "required" } }
}

Does anybody knows what is happening here ?
Thanks.