use v-model inside a v-for loop

Question

I am rendering an input field inside v-for loop and using v-model in that input to get the value of the input but when i type in any one of the input , the value is typed in every text field.

I have replicated my issue here in this fiddle

<div id="app">
  <h2>Todos:</h2>
  <ol>
    <li v-for="todo in todos">
      <label>
        <input type="text" v-model="score">

        <del v-if="todo.done">
          {{ todo.text }}
        </del>
        <span v-else>
          {{ todo.text }}
        </span>
      </label>
    </li>
  </ol>
</div>

new Vue({
  el: "#app",
  data: {
    score: [],
    todos: [
      { text: "Learn JavaScript", done: false },
      { text: "Learn Vue", done: false },
      { text: "Play around in JSFiddle", done: true },
      { text: "Build something awesome", done: true }
    ]
  },
})

Answer 1

Yes obviously that happens because you bind X Input fields on 1 Value. What you probably want is your score[] to get put in as an Array, for that use

new Vue({
  el: "#app",
  data: {
    score: [],
    todos: [
      { text: "Learn JavaScript", done: false },
      { text: "Learn Vue", done: false },
      { text: "Play around in JSFiddle", done: true },
      { text: "Build something awesome", done: true }
    ]
  },
})

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}

li {
  margin: 8px 0;
}

h2 {
  font-weight: bold;
  margin-bottom: 15px;
}

del {
  color: rgba(0, 0, 0, 0.3);
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>

<div id="app">
  <h2>Todos:</h2>
  <ol>
    <li v-for="(todo,index) in todos">
      <label>
    <input type="text" v-model="score[index]">

    <del v-if="todo.done">
      {{ todo.text }}
    </del>
    <span v-else>
      {{ todo.text }}
    </span>
  </label>
    </li>
  </ol>
</div>

https://jsfiddle.net/o9awn47v/

Answer 2

Score is treated as a single variable, when in it used in v-model="score".

You can add the score in the todo items and v-model it on the input, so you can easily reference to the score value of each todo item.

<div id="app">
  <h2>Todos:</h2>
  <ol>
    <li v-for="todo in todos">
      <label>
        <input type="text" v-model="todo.score">

        <del v-if="todo.done">
          {{ todo.text }}
        </del>
        <span v-else>
          {{ todo.text }}
        </span>
      </label>
    </li>
  </ol>
</div>

new Vue({
  el: "#app",
  data: {
    todos: [
      { text: "Learn JavaScript", done: false, score: '' },
      { text: "Learn Vue", done: false, score: '' },
      { text: "Play around in JSFiddle", done: true, score: '' },
      { text: "Build something awesome", done: true, score: '' }
    ]
  },
})