Set initial vuetify v-select value

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How to select default value using an attribute of an object

<template>

   <v-select v-model="input.user_id" :items="users" item-value="id" item-text="name" label="Users"/>

</template>

<script>
  export default {
    data: () => ({
        input: {
            user_id: 2,
        },
        users: [
          {
            id: 1,
            name: "John",
            last: "Doe"
          },
          {
            id: 2,
            name: "Harry",
            last: "Potter"
          },
          {
            id: 3,
            name: "George",
            last: "Bush"
          }
        ]
    }),
  }
</script>

Fiddle example: https://jsfiddle.net/4c3tbj6m/

Explain usage:

v-model is a special interfacing method for the value attribute of an <input /> field.

item-value="id" tells the input field what attribute of a selected object item row to set as the value of input.user_id

item-text="name" tells the field what attribute of a selected object item row to use to display as the selected text.

See Official Documentation on v-model.

Example above is a select field so v-model is representing value of what would be a selected attribute of an option element like the following:

<option value="1" selected>John</option>

The value of input.user_id is the selected item (value set by the v-model bind)

You can then POST the entirety of input (if more input fields are added) but in this case there is only user_id in there:

methods: {

  save() {

    axios.post('/my/api/example', this.input).then(response => {

      console.log(response);

    })

  }

}

<v-btn @click.prevent="save">SAVE</v-btn>

This will POST a JSON object to your servers end point /my/api/example formatted like this:

{
  "user_id": 1
}

I believe there are two issues with your set up. Firstly, the initial value should be one of the options in select, i.e., you should have people include your defaultSelected; Secondly your object needs to contain a value field, see v-select props. Otherwise you need to specify item-value prop; See a working example here.

<v-select
  item-text="name"
  item-value="last"
  v-model="defaultSelected"
  :items="people"
>

Vue.use(Vuetify);

 const vm = new Vue({
  el: "#app",
  data: {
    defaultSelected: {
      name: "John",
      last: "Doe"
    },
    people: [
      {
        name: "John",
        last: "Doe"
      },
      {
        name: "Harry",
        last: "Potter"
      },
      {
        name: "George",
        last: "Bush"
      }
    ]
  }
});