Decoding GraphQL with TypeScript: A Comprehensive Guide to Fetching, Schemas, and Exploration with GraphiQL

GraphQL and TypeScript are potent tools that can supercharge your web development skills. Let's explore the incredible journey of fetching data with the fetch API, understanding and using GraphQL schemas, and exploring them with GraphiQL.

Understanding GraphQL and TypeScript

Before we dive into the more advanced concepts, it's vital to understand what GraphQL and TypeScript are. GraphQL is a query language for APIs that provides a more efficient and robust way of building web applications. On the other hand, TypeScript is a statically typed superset of JavaScript, which means that it adds additional features to JavaScript, including a strong type system.

Fetching Data with GraphQL and Fetch API

The Fetch API provides a JavaScript interface for accessing and manipulating parts of the HTTP pipeline, like requests and responses. Even though libraries like Apollo and Relay are commonly used for interacting with GraphQL, the fetch API can do it as well. 

const query = `{allAsset{edges{node{src title}}}}`;

fetch('/graphql', { method: 'POST', headers: { 'Content-Type': 'application/json', 'Accept': 'application/json', }, body: JSON.stringify({ query }) }) .then(r => r.json()) .then(data => console.log('data returned:', data));

Understanding GraphQL Schema: A Comprehensive Guide

A GraphQL schema is a critical component of any GraphQL server implementation. It describes the shape of your data graph, including the types of data you can fetch and their relationship.

Defining a GraphQL Schema

A GraphQL schema is defined using the GraphQL Schema Definition Language (SDL). The SDL provides a set of types that are used to specify the schema's capabilities. Below are some of the most commonly used ones:

  1. ObjectType: This is the most common type of data you'll work with. It represents an object with fields.

  2. ScalarType: This type represents a primitive value. GraphQL's built-in scalar types include Int , Float , String , Boolean , and ID .

  3. EnumerationType (Enum): This type is a special kind of scalar that is restricted to a particular set of allowed values.

  4. InterfaceType: This type represents a collection of fields that multiple types can include.

  5. UnionType: This type represents an OR relation between other types.

Sample GraphQL Schema

Here's an example of what a typical GraphQL schema might look like: 

type Asset {
  _meta: CaisyDocument_Meta
  author: String
  copyright: String
  description: String
  dominantColor: String
  hideDescriptionAsCaption: Boolean
  id: ID
  keywords: String
  originType: String
  originalName: String
  src: String
  title: String
}

type Asset_Connection {
  edges: [Asset_ConnectionEdge]
  pageInfo: PageInfo
  totalCount: Int
}

type Asset_ConnectionEdge {
  cursor: String
  node: Asset
}

input Asset_CreateInput {
  description: String
  copyright: String
  title: String
  originalName: String
  dominantColor: String
  src: String
  keywords: String
  originType: String
  author: String
  hideDescriptionAsCaption: Boolean
}

input Asset_Sort {
  keywords: Order
  originType: Order
  author: Order
  dominantColor: Order
  description: Order
  hideDescriptionAsCaption: Order
  title: Order
  originalName: Order
  copyright: Order
}

input Asset_UpdateInput {
  dominantColor: String
  description: String
  originalName: String
  copyright: String
  originType: String
  author: String
  keywords: String
  src: String
  hideDescriptionAsCaption: Boolean
  title: String
}

input Asset_Where {
  author: CaisyField_String_Where
  hideDescriptionAsCaption: Boolean
  keywords: CaisyField_String_Where
  originType: CaisyField_String_Where
  dominantColor: CaisyField_Color_Where
  OR: [Asset_Where]
  AND: [Asset_Where]
  description: CaisyField_String_Where
  originalName: CaisyField_String_Where
  copyright: CaisyField_String_Where
  title: CaisyField_String_Where
}