Chain Client

The Chain client is your primary interface for executing GraphQL queries and mutations with full type safety.

Creating a Chain


import { Chain } from './zeus';
 
const chain = Chain('https://your-api.com/graphql');

With Configuration


const chain = Chain('https://your-api.com/graphql', {
  headers: {
    Authorization: 'Bearer your-token',
    'X-Custom-Header': 'value',
  },
});

Authentication

Bearer Token


const chain = Chain('https://api.com/graphql', {
  headers: {
    Authorization: `Bearer ${process.env.API_TOKEN}`,
  },
});

Dynamic Headers


function createAuthenticatedChain(token: string) {
  return Chain('https://api.com/graphql', {
    headers: {
      Authorization: `Bearer ${token}`,
    },
  });
}
 
const userChain = createAuthenticatedChain(userToken);

Refresh Token Pattern


let currentToken = 'initial-token';
 
function getChain() {
  return Chain('https://api.com/graphql', {
    headers: {
      Authorization: `Bearer ${currentToken}`,
    },
  });
}
 
// Update token
async function refreshToken() {
  // ... refresh logic
  currentToken = newToken;
}

Error Handling


try {
  const result = await chain('query')({
    user: [{ id: '123' }, { name: true }],
  });
  console.log(result.user.name);
} catch (error) {
  if (error instanceof Error) {
    console.error('GraphQL Error:', error.message);
 
    // Handle specific error types
    if (error.message.includes('Unauthorized')) {
      // Refresh token or redirect to login
    }
  }
}

Batch Requests

Execute multiple operations in a single request:


const results = await Promise.all([
  chain('query')({ user: [{ id: '1' }, { name: true }] }),
  chain('query')({ posts: { title: true } }),
  chain('query')({ categories: { name: true } }),
]);
 
const [userData, postsData, categoriesData] = results;

Custom Fetch

Use with custom fetch implementation:


const chain = Chain('https://api.com/graphql', {
  headers: {},
  fetch: customFetch, // Your custom fetch function
});

Next Steps

Selectors - Reusable selection sets
Thunder - Custom fetch with full control
Type Inference - Understanding types

Explore Selectors →