README.md

This is a repository demonstrating how to actually set up GraphQL with PHP but also how to mitigate the infamous n+1 problem by deferring the actual field resolution to a later stage. This implementation uses DataloaderPHP for the dererral.

The project is set up on top of Slim Framework v4 which acts as an API. Slim provides out-of-the-box Monolog support with their Skeleton project that you can use to actually log database queries and see what happens.

Database connection is handled using Doctrine DBAL and logged with an SQLLogger instance.

GraphQL implementation is provided by webonyx/graphql-php

Instructions

• Download
• Unpack
• Set up a database table (I used MySQL here) and import the database.sql
• Add your database connection settings to app/settings.php db section. Defaults are set to localhost demo database.
• cd to project root and run:

composer install

• Run PHP app with:

php -S localhost:8080 -t public public/index.php

Testing

After you app is running use Postman or any tool you like to send a GraphQL body request to your API which should now be running at http://localhost:8080

query {
    getBooks {
        id
        title
        author {
            id
            name
        }
    }
}

You can afterwards check your logs/app.log for the database queries that were executed. The log entry should look like this:

{
  "1": {
    "sql": "SELECT * FROM book",
    "params": [],
    "types": [],
    "executionMS": 0.00038886070251464844
  },
  "2": {
    "sql": "SELECT id, `name` FROM author WHERE id in (?)",
    "params": [
      [
        "1",
        "2",
        "3"
      ]
    ],
    "types": [
      101
    ],
    "executionMS": 0.0014162063598632812
  }
}

So we fetched the books in one query and after getting all the possible author ids for all the books, we queried them in one go.

Credits

I wanna credit Ben Awad whose demo project got me on the right track with using DataLoder to handle promises and setting up field resolvers.