graphql-defragmentizer

Library for building GraphQL queries from fragments in JavaScript.

It combines the main query, the fragments and their sub-fragments into one valid query. Useful for React apps, if you want each component to specify its own data requirements, but still want to run a single GraphQL query.

It can be used on React components in a way similar to prop-types declarations.

There's no dependency on React and can be used by all kinds of GraphQL clients.

Status

We're using it in production at SVT and will likely fix problems if we encounter any. Contributions are welcome!

API

createQuery`...`

Creates a GraphQL Document from a template string.

Values are usually fragments (created by createFragment). Fragments must be placed where you would normally place the name of a fragment.

If the values aren't fragments, they'll be appended to the query (with String() conversion).

The query and the fragments (and their sub-fragments) will be recursively combined into a valid GraphQL query, combining any duplicate fragments into one.

If you don't use fragments, it's mostly identical to the gql`...` function of graphql-tag.

Usage:

const query = createQuery`
  query MyQuery {
    someQuery {
      ... ${myFragment}
    }
  }`;

createFragment`...`

Creates a fragment from a template string, for use by createQuery or a parent createFragment call.

The template string must be a valid GraphQL fragment definition, but without the name. It can have other fragments as values.

If the values aren't fragments, they'll be appended to the fragment (with String() conversion).

Usage:

const fragment = createFragment`
  ... on MyThing {
    name
    friends {
      ... ${friendFragment}
    }
  }`;

Example with React

Showing a latest news list on a web page:

Main.js:

import { createQuery } from 'graphql-defragmentizer';
import { graphql } from 'react-apollo';

const MainQuery = createQuery`
  query MainQuery {
    main {
      latestNews {
        ...${LatestNews.fragments.latestNews}
      }
      mainTitle
    }
  }
`;

function Main({ mainTitle, latestNews }) {
    return
      <div>
        <h1>{mainTitle}</h1>
        <p><LatestNews latestNews={latestNews} /></p>
      </div>
}

export default graphql(MainQuery,
  props: props => ({
    latestNews: props.data.main.latestNews,
    mainTitle: props.data.main.mainTitle 
  })
)(Main);

LatestNews.js:

import { createFragment } from 'graphql-defragmentizer';

export default function LatestNews({ latestNews }) {
  return latestNews.map((item) => {
     <a href={url}>{title}</a>
  }
}

LatestNews.fragments = {
  latestNews: createFragment`
    ... on LatestNewsItem {
      title
      url
    }
  `
};

This would build a query like this:

query MainQuery {
  main {
    latestNews {
      ...fragment_fevfrc
    }
    mainTitle
  }
}

fragment fragment_fevfrc on LatestNewsItem {
  title
  url
}

The name "fragment_fevfrc" is created by hashing the contents and type of the fragment, so two identical fragments will be merged into one.

License

graphql-defragmentizer is released under the MIT License.

Getting involved

Feel free to issue pull requests or file issues. For more details, see CONTRIBUTING

Primary Maintainer

Anders Kindberg https://github.com/ghostganz

Credits

Original implementation by Emil Broman.