Troubleshooting Vue template issues with updating values in the composition API

Question

Troubleshooting Vue template issues with updating values in the composition API

I am facing an issue with a functional component:

export default defineComponent({
  name: 'MovieOverview',
  components: {
    ExpandedMovieInformation,
  },
  setup() {
    let toggleValue = false;

    const toggleExpandedMovieInformation = (moviex: Movie) => {
      toggleValue = !toggleValue;
      console.log(toggleValue)
    };

    return {
      toggleValue,
      toggleExpandedMovieInformation,
    };
  },
});

<template>
  <div>
    <button v-on:click='toggleExpandedMovieInformation'>click</button>
    {{ toggleValue }}
  </div>
</template>

Although the console.log shows the updated value when the button is clicked, the template doesn't reflect the changes and continues to show the initial value of false.

vue.js vue-composition-api

Answer 1

Answer №1

To ensure reactivity in the toggleValue variable, you need to utilize either ref() or reactive(). This will allow the view to re-render whenever changes are made to that property.

Here is an example of how you can achieve this:

import { ref } from 'vue'

export default defineComponent({
  name: 'MovieOverview',
  components: {
    ExpandedMovieInformation,
  },
  setup() {
    let toggleValue = ref(false);

    const toggleExpandedMovieInformation = (movie: Movie) => {
      // update the value using the `value` property
      toggleValue.value = !toggleValue.value;
      console.log(toggleValue.value)
    };

    return {
      toggleValue,
      toggleExpandedMovieInformation,
    };
  },
});

<template>
  <div>
    <button v-on:click='toggleExpandedMovieInformation'>Click</button>
    <!-- No need to change toggleValue to toggleValue.value in the template -->
    {{ toggleValue }}
  </div>
</template>

For more information on ref and reactive, refer to the documentation.

Answer 2

To ensure reactivity in the toggleValue variable, you need to utilize either ref() or reactive(). This will allow the view to re-render whenever changes are made to that property.

Here is an example of how you can achieve this:

import { ref } from 'vue'

export default defineComponent({
  name: 'MovieOverview',
  components: {
    ExpandedMovieInformation,
  },
  setup() {
    let toggleValue = ref(false);

    const toggleExpandedMovieInformation = (movie: Movie) => {
      // update the value using the `value` property
      toggleValue.value = !toggleValue.value;
      console.log(toggleValue.value)
    };

    return {
      toggleValue,
      toggleExpandedMovieInformation,
    };
  },
});

<template>
  <div>
    <button v-on:click='toggleExpandedMovieInformation'>Click</button>
    <!-- No need to change toggleValue to toggleValue.value in the template -->
    {{ toggleValue }}
  </div>
</template>

For more information on ref and reactive, refer to the documentation.

Troubleshooting Vue template issues with updating values in the composition API

Answer №1

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