fix(VDatePicker): show correct week number for selected locale

[simon-tackstrand]

Description

Current getWeek implementation does not work for different locales.
Uses @date-io adapter to calculate week number.

resolves #20490, #20724

Requires @date-io version >= 3.2.0 for any project referencing vuetify

The previous getWeek implementation has been moved to the VuetifyDateAdapter, meaning the bug will still exist for those not using any @date-io implementation.

Markup:

<template>
  <v-app>
    <v-container>
      <v-row>
        <v-col cols="12">
          <div style="height: 600px">
            <v-locale-provider locale="sv">
              <v-date-picker show-week />
            </v-locale-provider>
          </div>
        </v-col>
      </v-row>
    </v-container>
  </v-app>
</template>

<script>
  export default {
    name: 'Playground',
    setup () {
      return {
        //
      }
    },
  }
</script>

[johnleider]

Are you saying the only way to resolve this is to require a dependency?

[simon-tackstrand]

Are you saying the only way to resolve this is to require a dependency?

The dependency '@date-io' is already included in vuetify 3 so it is already required. With this PR we have just updated to a version which has a method for "getWeek". This enables anyone to get a correct getWeek implementation for all locales using any @date-io adapter compared to currently where a vuetify specific method is always used, even when a @date-io adapter is provided.

The VuetifyDateAdapter will still work for 'en-US', but this PR does NOT resolve the issue for locales where it calculates the week incorrectly. I will leave it for you to decide on how to proceed going forward with updating the VuetifyDateAdapter, in my point of view it is rather complex to get it correct for all locales since it requires information about each locale. An easier alternative could be a vuetify 2 inspired approach where the API allows the user to specify locale-first-day-of-year.

The approach in this PR will allow anyone using a @date-io adapter to get a correct locale specific getWeek implementation. For those choosing to use the VuetifyDateAdapter the functionality will remain unchanged.

I would suggest to include this in the next release of Vuetify to give an option for those having issues and being without any alternative other than to disable 'show-week'. The issues with the VuetifyDateAdapter can then be addressed later.