How to solve Vue error: Unable to correctly use v-model for two-way data binding

Introduction:
Vue is a popular front-end framework that provides It comes with many convenient features, including the v-model directive for two-way data binding. However, sometimes we may encounter some errors when using v-model, especially when dealing with complex data structures. This article will introduce several common v-model errors and provide solutions and code examples.

1. Error: Two-way binding of v-model to object properties does not work
   When we try to use the v-model directive to bind an object property to an input box, we sometimes find that the two-way binding Invalid binding.

Solution:
We need to ensure that the object properties are known, that is, declared in the data option of the Vue component. If we try to bind an undeclared property, Vue will not be able to track changes to this property. Here is a code example of a solution:

<template>
  <div>
    <input v-model="user.name" type="text" />
  </div>
</template>

<script>
export default {
  data() {
    return {
      user: {
        name: ""
      }
    };
  }
};
</script>

2. Error: v-model does not work in a loop
   When we try to use the v-model directive in a loop, we may find that only The two-way binding of the last element works.

Solution:
When using v-model in a loop, we need to provide a unique key for each binding so that Vue can correctly track the state of each input box. Here is a code example of a solution:

<template>
  <div>
    <div v-for="item in items" :key="item.id">
      <input v-model="item.value" type="text" />
    </div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      items: [
        { id: 1, value: "" },
        { id: 2, value: "" },
        { id: 3, value: "" }
      ]
    };
  }
};
</script>

3. Error: v-model cannot correctly get the value inside the component
   When we try to use v-model inside a custom component, it may You will find that the parent component cannot correctly obtain the value inside the child component.

Solution:
In order for v-model to work in a custom component, we need to explicitly specify the names of the internal values ??and events inside the component. Here is a code example of a solution:

<template>
  <div>
    <input :value="innerValue" @input="updateValue($event.target.value)" type="text" />
  </div>
</template>

<script>
export default {
  props: ['value'],
  data() {
    return {
      innerValue: ''
    };
  },
  methods: {
    updateValue(val) {
      this.innerValue = val;
      this.$emit('input', val);
    }
  },
  mounted() {
    this.innerValue = this.value;
  }
};
</script>

Using this custom component in a parent component, we can use v-model like this:

<template>
  <div>
    <custom-component v-model="parentValue" />
  </div>
</template>

<script>
import CustomComponent from './CustomComponent.vue';

export default {
  components: { CustomComponent },
  data() {
    return {
      parentValue: ''
    };
  }
};
</script>

Conclusion:
When using v When -model performs two-way data binding, we may encounter some errors. This article introduces several common error situations and provides solutions and code examples. I hope this information can help you use v-model better and also improve your Vue development efficiency.

The above is the detailed content of How to solve Vue error: Unable to use v-model correctly for two-way data binding. For more information, please follow other related articles on the PHP Chinese website!