GraphQL, what is it?

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GraphQL is a technology used to query an API. It is available for main programming languages just by adding the library to your project: no need for a new machine or any system installation.

GraphQL has nothing to do with SQL or any database related technology. There is however some similarities in the basic concepts:

• There is a client and a server.
• The client sends a human readable request containing some filters and the expected fields in the response.
• These fields can be complex objects, allowing to follow links between data.
• The language uses a vocabulary based on the data handling: query, mutation.

Example of GraphQL query
{
  tutorial(id: "graphql-what-is-it") {
    title,
    description,
    tags {
      name
    },
    author {
      name,
      social
    }
  }
}

Example of GraphQL response
{
  "data": {
    "tutorial": {
      "title": "GraphQL, what is it?",
      "description": "A quick explanation of GraphQL for beginners with examples.
                      Why use it? How does it work? Where to start?",
      "tags": [
        {
          "name": "what-is-it"
        },
        {
          "name": "api"
        },
        {
          "name": "graphql"
        }
      ],
      "author": {
        "name": "Nicolas Gautron",
        "social": {
          "linkedin": "https://fr.linkedin.com/in/nicolasgautron",
          "twitter": "https://twitter.com/gautronnicolas",
          "github": "https://github.com/nicolas-gautron"
        }
      }
    }
  }
}

GraphQL is mainly used through HTTP in order to replace a REST architecture.

The main advantages of GraphQL over REST:

• Only one HTTP request for querying linked data.
• Only the needed data for your use case is retrieved.
• The request variables and the response fields are strongly typed by the GraphQL engine.
• You can name the request, easing the logging and the debugging: improving the maintainability.

Any HTTP client can be used. Postman, for instance, natively include GraphQL in its last versions.

Learn more about GraphQL on the official site.

Have a nice day :)