Welcome in another episode of our Code Academy series in which we present the most interesting code related things like tools, libraries, approaches etc. This week we will cover a GraphQL schema visualization topic.

As your probably already know [GraphQL was defined by npm as one of the technologies that will dominate 2019.](https://graphqleditor.com/blog/javascript-predictions-for-2019-by-npm/)
GraphQL is a technology you must learn this year to keep up the pace of the frontend and the backend evolution. As for now, [RESTful APIs](https://graphqleditor.com/blog/graphql-vs-rest/) are the most popular choice but this will change soon. The sooner you make a decision to start the transition from REST to GraphQL the less painful its going to be. There are many tools and libraries to make it easier to convert from [REST to GraphQL](https://graphqleditor.com/blog/graphql-vs-rest-caching/) and there is a huge reward waiting for you at the end of the road.

## Know your schema

#### What’s a GraphQL schema and why it's so important to know it well?

The [GraphQL schema](https://graphql.org/learn/schema/) is a centerpiece of your GraphQL project. GraphQL schema is nested in your GraphQL server and defines every functionality available to the clients. The main element of each schema is `type` which allows establishing relations between different types, define allowed GraphQL operations (Queries and Mutations) to be performed on the server and more.

To make it easier to understand the operation that a server can perform GraphQL defined a universal schema syntax know as SDL (Schema Definition Language). The SDL defines the elements of your project i.e. `type`:

```gql
type Movie {
  title: String
  Director: Director
}

type Director {
  name: String
  movies: [Movie]
}
```

or `query` (asking the server for the data) and `mutation` (manipulating the data):

```gql
type Query {
  getMovies: [Movie]
  getDirectors: [Director]
}
```

```gql
type Mutation {
  addMovie(title: String, director: String): Movie
}
```

So as you see the schema is indeed a centerpiece of any GraphQL project and it's important to be aware of what is what and where to find it. Big complicated schemas are really hard to comprehend. Let's take GitHib schema as an example, it has **9182** lines of code! It's really hard to follow... Fortunately, graphs are coming with help!

## Visualization is the key

A graph is an abstract data type. It's structure consists of a finite set of vertices, nodes or points linked together. Graphs are a great tool for shaping logic behind your app as they fit-in well for any IT project and at this point, we can agree that graphs are more accessible than code in terms of apprehending the schema.

#### Turning schema code into graphs

So how can we turn our schema code into a visual graph? It's simpler than you can imagine. We are going to use [GraphQL Editor](https://graphqleditor.com).

All you need to do is go to [app.graphqldditor.com](https://app.graphqleditor.com)and load your schema as below and ...

![Load your schema URL](https://graphqleditorcms.fra1.cdn.digitaloceanspaces.com/graphqleditorcms/blogpost/schemaurl-1730850823599.webp)

... and that's it!

If you have provided editor a valid schema it will automatically turn its code into a visual graph. Cool, right?

![Your schema turned into a graph](https://graphqleditorcms.fra1.cdn.digitaloceanspaces.com/graphqleditorcms/blogpost/result-1730850820843.webp)

Code Academy - How to visualize your GraphQL schema?

Ready for take-off?

For GraphQL cache can significantly improve performance and reduce redundancy, particularly when the same data is queried multiple times within a short timeframe. In this post, I'll go over implementing caching using [GraphQL Zeus](/docs/zeus) to fetch data from our custom CMS. No worries this can also be applied just as effectively to other GraphQL APIs, such as Hygraph or Hasura. Whether you’re working with a headless CMS, an e-commerce backend, or any other GraphQL-powered service, caching is just as important in every scenario and the implementation should look very similar.

## Why Add Caching?

Caching provides a number of advantages like:
 -  Reduced Server Load: By serving repeated requests from the cache, you avoid making unnecessary calls to the GraphQL server, which can be essential for scaling applications with high traffic.
 - Improved Performance: frequently requested data can be served directly from memory, reducing query response time significantly
 - Cost Efficiency: if your GraphQL API usage is metered (e.g., cloud-based APIs), caching significantly reduces the number of queries made, saving on usage costs

## [GraphQL Zeus](/docs/zeus) query example

Let’s start with a simple query I made using [GraphQL Zeus](/docs/zeus), which fetches homepage data from our CMS:

```ts
export const getHomepageData = async () => {
  try {
    const result = await chain('query')({
      onehomepageBySlug: [{ slug: 'home' }, HomepageDataSelector],
    });
    return result;
  } catch (error) {
    console.error('failed to fetch home data', error);
  }
};
```

This query retrieves all the homepage data at once and passes it to the relevant components. This allows users to update the homepage content directly through the CMS without needing to modify any code. Currently, this function is called in server-side props, meaning it triggers an API call every time the page is refreshed or visited.

To optimize this and reduce redundant API calls, we’ll implement caching by using the [node-lru-cache](https://github.com/isaacs/node-lru-cache) library.

## LRU cache

LRU stands for "Least Recently Used," a caching strategy that automatically removes the least recently accessed items when the cache reaches its limit. The node-lru-cache library offers several configuration options, but in our case to set up a basic GraphQL cache, we only need two key settings:

 - `ttl` (Time to Live): This setting defines how long an item stays in the cache before it’s considered expired, specified in milliseconds.
 - `ttlAutopurge`: When enabled, this option automatically deletes expired items from the cache. Without it, expired items are only purged when the cache is next accessed which can potentially lead it to grow unbounded.
 
```ts
import { LRUCache } from 'lru-cache';

const cache = new LRUCache({
  ttl: 1000 * 60 * 5, // Set time to live to 5 minutes
  ttlAutopurge: true,  // Automatically clean up expired entries
});
```

## Caching the query

To cache the query I mentioned earlier, we need to do three simple things:
1. Set up a cache key: This helps the cache know which entry to return when the same data is requested. You can name the key however you like, but it has to be unique to avoid conflicts.
2. Check if the cache contains the result: If the cache has the entry for that key, return the cached result.
3. Store the query result in the cache: After fetching the data, save the result in the cache for future use.

```ts
export const getHomepageData = async () => {
  const cacheKey = 'homepageData'; // Cache key for this entry
  if (cache.has(cacheKey)) { // Check if the cache contains this key
    return cache.get(cacheKey) as { onehomepageBySlug: HomepageDataType }; // Return cached result
  } 
  try {
    const result = await chain('query')({
      onehomepageBySlug: [{ slug: 'home' }, HomepageDataSelector],
    });
    cache.set(cacheKey, result); // Store query result in the cache
    return result;
  } catch (error) {
    console.error('failed to fetch home data', error);
  }
};
```

This approach results in two scenarios:

 - First visit: The query runs, fetches the data, and caches it for future use.
 - Subsequent visits (within the TTL): The cached result is returned, avoiding the need to make a new API request.

## Query with params (slug, locale)

As mentioned earlier, the cache key must be unique to avoid conflicts. This is especially important for queries that include parameters, such as `locale` (for localization) or `slug` (for specific blog pages). Without unique cache keys, you may end up with the same content being served for different locales or blog pages. To avoid this, it's best to use a dynamic cache key based on the query parameters.

```ts
export const getBlogpostBySlug = async ({ slug }: { slug: string }) => {
  const cacheKey = `Blogpost:${slug}`; // Unique cache key based on the slug
```

By using this dynamic approach, we ensure that the correct data is returned for the given slug. If you were to use a static cache key like 'blogpost', you'd always get the first cached blog post, regardless of which slug is provided. The same issue would arise with localization: without unique keys, you'd end up serving the wrong content for different locales.

## Its all about performance

GraphQL is all about efficiency — retrieving only the data you need (unlike REST). It makes sense to take that a step further to further enhance performance. With a GraphQL cache setup like this we can reduce redundant API calls and significantly speed up queries, especially for frequently accessed data like homepage content or blog posts. Dynamic cache keys based on query parameters ensure that the data is correctly localized or filtered according to specific slugs and [GraphQL Zeus](/docs/zeus) and selectors keep everything type-safe. Together this solution can greatly improve your app's speed and scalability. As mentioned, even if you're not using [GraphQL Zeus](/docs/zeus), the implementation should still be very similar to the above, so give it a try!
  

GraphQL cache: using LRU cache with GraphQL Zeus

Unlocking the Power of React 19

Welcome to a short post about a recent quality of life update to [GraphQL Zeus](/docs/zeus). If you're not familiar with [GraphQL Zeus](/docs/zeus) go ahead and read my [earlier post which breaks down its basics](/what-is-graphql-zeus). If you are lets go ahead and talk about the update!

### Graphql Fragments

GraphQL has long supported reusable fields natively with the use of fragments. If you're not familiar with them basically if you had the same fields in multiple queries you could define a fragment - a set of fields, and then reuse it instead of repeating all the fields every time. Lets say you had a user with some fields like name, email, address. Then you could use a fragment like this:

```ts
query getUser {
  user(id: 4) {
    ...userFields
  }
}

fragment userFields on User {
  name,
  email,
  address,
  avatar
}
```

For reusability you could put all your fragments in a fragments.js file and then use them across a project. Zeus already had a solution like Selectors (which work a bit similarly to that) but with the latest update it can now go a step further! :)

### Zeus fields - GraphQL spread operator

For our example lets say we need to get the posts data for our blog page where we display them in a grid, usually the query that would look something like this:

```ts
const posts = await Chain('http://example.com/api/graphql')('query')({
  posts: [
    {
      title: true,
      coverImage: true,
      publishedAt: true,
      slug: true,
      content: { markdown: true },
    },
  ],
});
```

With Zeus 6.0.0 you can simply use a spread operator `...fields` with the TypeScript type from the schema (eg. `Post`) to simply get all the fields available for that type:

```ts
const posts = await Chain('http://example.com/api/graphql')('query')({
  posts: [
    {
      ...fields('Post'),
    },
  ],
});
```

### Never go full REST

With this, we now have a convenient quality-of-life improvement for cases where you just want to quickly retrieve all the fields for a type. That said it's important to remember what GraphQL is all about - getting exactly what you requested without overfetching. So don't just use `...fields` everywhere or you'll defeat the entire purpose of using GraphQL in the first place and turn it into REST, always pulling way more data than necessary.


Code Academy - How to visualize your GraphQL schema?

Know your schema

What’s a GraphQL schema and why it's so important to know it well?

Visualization is the key

Turning schema code into graphs

Check out our other blogposts

Ready for take-off?

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