Getting started with Vue Query and TypeScript

What is Vue Query?

It is based on React Query and inherits all of its concepts from the main package.

It works in both Vue 2 with the Composition API plugin and Vue 3.

Installing Vue Query

To install Vue Query, we run the following command in a terminal:

yarn add vue-query

Using Vue Query

Vue Query requires a query provider attached in the root of our application.

import { defineComponent } from 'vue';
import { useQueryProvider } from 'vue-query';

export default defineComponent({
  name: 'App',
  setup() {
    useQueryProvider();
  },
});

useQueryProvider provides our app an instance of the QueryClient class from the react-query/core package.

In a component that fetches data, a useQuery hook allows us to specify our function that fetches data:

import { defineComponent } from 'vue'
import { useQuery } from 'vue-query';
...
export default defineComponent({
    name: 'Todos',
    setup() {
       const { data, isLoading, isError } = useQuery(
           'todos', // query key
           getTodos // fetching function
       )

       return {
            data,
            isLoading,
            isError
       }
    }
})

As you can see with useQuery the first argument is a simple string. This caches and tracks the result of that query.

The second argument is how we actually get the data. It either needs to resolve data or throw an error.

useQuery has generic parameters for the type of the data that is being fetched and the error type if a failure occurs:

useQuery<Todo[], Error>(
  'todos',
  getTodos
);

Error is the standard error object.

The Todo type is as follows:

type Todo = {
    userId: number
    id: number
    title: string
    completed: boolean
}

Fetching function

The fetching function implementation is as follows:

async function getTodos() {
    const response = await fetch('https://jsonplaceholder.typicode.com/');
    return response.json();
}

Finishing the component

Here’s the rest of the component implementation:

<template>
    <div v-if="isLoading">Loading...</div>
    <div v-else-if="isError">{{ error!.message }}</div>
    <div v-else>{{ JSON.stringify(data) }}</div>
</template>

<script lang="ts">
import { defineComponent } from 'vue'
import { useQuery } from 'vue-query'

type Todo = {
    userId: number
    id: number
    title: string
    completed: boolean
}

export default defineComponent({
    name: 'Todos',
    setup() {
       const { data, isLoading, isError, error } = useQuery<Todo[], Error>(
           'todos',
           getTodos
       )

       return {
            data,
            isLoading,
            isError,
            error
       }
    }
})
</script>