Taming the Reactivity Beast: Using Vue Reactive Variables with Urql and graphql-codegen
When building a Vue application with a GraphQL backend, combining the power of Urql for data fetching and graphql-codegen for efficient type generation can lead to a streamlined development experience. But one common hurdle arises when you want to use Vue reactive variables directly within your GraphQL queries. This article explores the challenge and offers a solution for seamless reactivity within your Urql setup.
The Problem: Static Queries and Dynamic Needs
Imagine you're building a product listing page where users can filter products by category. You've generated your GraphQL types using graphql-codegen, and you're using Urql to execute your queries. The problem arises when you want to pass the user-selected category (a Vue reactive variable) into your GraphQL query.
Here's a simplified example of the issue:
import { gql } from 'graphql-tag'
import { useQuery } from 'urql'
// Generated types from graphql-codegen
import { ProductsQuery } from './generated/graphql'
const category = ref('Electronics')
const { data, fetching, error } = useQuery({
query: gql`
query Products($category: String!) {
products(category: $category) {
id
name
price
}
}
`,
variables: {
category: category.value // Problem: This is static, not reactive
}
})
The issue lies in the variables object. We're passing the value of the category reactive variable, which is a static value. When the category variable changes, the query won't automatically re-execute, causing our product listing to remain stale.
The Solution: Reactive Variables with Urql
To overcome this, we can leverage the powerful useQuery hook's ability to accept a function that returns the query parameters. This allows us to dynamically update the query variables based on reactive data changes.
Here's the revised code:
import { gql } from 'graphql-tag'
import { useQuery } from 'urql'
// Generated types from graphql-codegen
import { ProductsQuery } from './generated/graphql'
const category = ref('Electronics')
const { data, fetching, error } = useQuery({
query: gql`
query Products($category: String!) {
products(category: $category) {
id
name
price
}
}
`,
variables: () => ({ category: category.value }) // Dynamic variables!
})
By wrapping the variables in a function, we now provide Urql with a function that dynamically retrieves the current value of the category reactive variable. This ensures the query will re-execute whenever the category value changes, guaranteeing a reactive update of your product listing.
Advantages and Considerations
This approach offers several advantages:
- True Reactivity: Your product listing will automatically update as the user changes the category filter, enhancing user experience.
- Clean Code: You maintain the separation of concerns by keeping your Vue reactivity logic within your component while relying on Urql's powerful data fetching capabilities.
- Scalability: This technique works seamlessly for any reactive data used as query variables, ensuring your application remains responsive as you add more features.
However, be aware of potential performance implications if you're dealing with complex data or frequent reactive changes.
Conclusion
Using reactive variables with Urql and graphql-codegen is a simple yet powerful way to build dynamic, responsive Vue applications. By leveraging the useQuery hook's ability to accept a function for query variables, you can seamlessly integrate reactive data from your Vue components into your GraphQL queries, creating a smooth and reactive user experience.
