Efficiently Managing Remote Data in Vue with Vue Query

When building modern Vue applications, efficiently managing remote data is crucial for creating responsive and user-friendly interfaces. Vue Query, inspired by React Query, provides powerful hooks for fetching, caching, and synchronizing server state in your Vue applications. In this post, we'll explore three essential hooks: useQuery, useQueryClient, and useMutation, and how they can transform your data management approach.

Introduction to Vue Query

Vue Query simplifies data fetching and state management by providing hooks that handle the complexities of remote data. It helps in reducing boilerplate code and ensures data consistency across your application. Let’s dive into the three key hooks and understand their usage.

useQuery: Simplified Data Fetching

useQuery is a fundamental hook for fetching data from an API and managing the loading, error, and success states. It's ideal for simple data-fetching needs where you want to display data and handle the associated states.

Example: Fetching Todos

import { useQuery } from 'vue-query'
import { fetchTodos } from '@/api'

export default {
  setup() {
    const { data, error, isLoading } = useQuery('todos', fetchTodos)

    return {
      todos: data,
      error,
      isLoading
    }
  }
}

In this example, useQuery fetches a list of todos from the fetchTodos API function. It returns data, error, and isLoading states that you can use in your template to display the data or show loading and error messages.

useQueryClient: Advanced Query Management

While useQuery handles individual queries, useQueryClient gives you access to the query client, enabling advanced operations like invalidating, refetching, and updating queries. It’s useful for managing global query state and ensuring data consistency.

Example: Invalidating Queries

import { useQueryClient } from 'vue-query'

export default {
  setup() {
    const queryClient = useQueryClient()

    const invalidateTodos = () => {
      queryClient.invalidateQueries('todos')
    }

    return {
      invalidateTodos
    }
  }
}

In this example, useQueryClient is used to get the query client instance. The invalidateTodos function invalidates the todos query, forcing it to refetch the data. This is particularly useful after performing data mutations to ensure the UI reflects the latest server state.

useMutation: Managing Data Modifications

useMutation is designed for data-modifying operations like creating, updating, or deleting data. It handles the various states (loading, error, success) and provides options for optimistic updates and side-effect management.

Example: Creating a Todo

import { useMutation, useQueryClient } from 'vue-query'
import { addTodo } from '@/api'

export default {
  setup() {
    const queryClient = useQueryClient()

    const mutation = useMutation(addTodo, {
      onSuccess: () => {
        queryClient.invalidateQueries('todos')
      },
      onError: (error) => {
        console.error('Error adding todo:', error)
      }
    })

    const createTodo = async (newTodo) => {
      try {
        await mutation.mutateAsync(newTodo)
      } catch (error) {
        console.error('Error during mutation:', error)
      }
    }

    return {
      createTodo,
      mutation
    }
  }
}

In this example, useMutation handles the addition of a new todo. Upon success, it invalidates the todos query to refetch the updated list. You can also manage errors and other side effects through the provided callbacks.

Advanced Usage: Optimistic Updates

Optimistic updates enhance the user experience by immediately updating the UI before the server confirms the mutation. This can make your application feel more responsive.

Example: Optimistic Updates

import { useMutation, useQueryClient } from 'vue-query'
import { addTodo } from '@/api'

export default {
  setup() {
    const queryClient = useQueryClient()

    const mutation = useMutation(addTodo, {
      onMutate: async (newTodo) => {
        await queryClient.cancelQueries('todos')
        const previousTodos = queryClient.getQueryData('todos')
        queryClient.setQueryData('todos', old => [...old, newTodo])
        return { previousTodos }
      },
      onError: (err, newTodo, context) => {
        queryClient.setQueryData('todos', context.previousTodos)
        console.error('Error adding todo:', err)
      },
      onSettled: () => {
        queryClient.invalidateQueries('todos')
      }
    })

    const createTodo = async (newTodo) => {
      try {
        await mutation.mutateAsync(newTodo)
      } catch (error) {
        console.error('Error during mutation:', error)
      }
    }

    return {
      createTodo,
      mutation
    }
  }
}

In this example, onMutate performs an optimistic update by immediately adding the new todo to the local state. If the mutation fails, onError rolls back to the previous state using the context object.

Conclusion

Vue Query, with its powerful hooks like useQuery, useQueryClient, and useMutation, provides a robust solution for managing remote data in Vue applications. By simplifying data fetching, synchronization, and state management, it helps you build responsive and efficient applications with less boilerplate code.

Whether you’re fetching data, invalidating queries, or performing optimistic updates, Vue Query streamlines the process, making it easier to keep your UI in sync with your server state. Embrace these hooks to elevate your Vue development experience and deliver seamless user interactions.