GraphNoQL

Facebook's GraphQL backend implemented with Node+Mongo

Brief

./source/js/modules/queryEngine.js is the primary module in this project, which takes in a query object (defined in ./docs/schema.md)", and a callback. It then makes a bunch of mongo queries and returns the requested tree to a callback.

Example

We have tweaked Facebook's GraphQL format to be JSON compatible. The biggest change is that we got rid of calls, and use string id's for root node queries, and special Edge objects for querying edges.

Let's look at an example query:

{
  nodeidtest: {       // Give a Node ID for us to start from
    id: true,         // Define which fields we want to return
    test: true,
    name: true,
    friends: {        // A special <Edge> object for the friends set
      get: {          // rules for how to traverse edge
        all: true,
      },              // A model of the data to return
      node: {
        id: true,
        test: true,
        name: true
      }
    }
  }
}

This query would start at the root node with id === 'nodeidtest', getting the id, test, and name fields. Then it would traverse the friends edge, finding related nodes according the rules set by the edge.get hash. For each found node, it would return the fields defined in edge.node if this node include edges, it will continue making queries until it has found everything requested.

And example response might look like:

{
  nodeidtest: {
    id: "nodeidtest",
    test: "nodeidtest.test",
    name: "nodeidtest.name",
    friends: [
      {
        id: "friend1",
        test: "friend1.test",
        name: "friend1.name"
      }, {
        id: "friend2",
        test: "friend2.test",
        name: "friend2.name"
      }
    ]
  }
}

Here's the Mongo documents which would generate that response form that query:

####NodeIdTest

{
  id: "nodeidtest",
  test: "nodeidtest.test",
  name: "nodeidtest.name",
  friends: [
    {
      cursor: 1,
      node: {
        id: "friend1"
      }
    },
    {
      cursor: 2,
      node: {
        id: "friend2"
      }
    }
  ]
}

####Friend1

{
  id: "friend1",
  test: "friend1.test",
  name: "friend1.name",
  friends: [
    {
      cursor: 1,
      node: {
        id: "nodeidtest"
      }
    }
  ]
}

####Friend2

{
  id: "friend2",
  test: "friend2.test",
  name: "friend2.name",
  friends: [
    {
      cursor: 1,
      node: {
        id: "nodeidtest"
      }
    }
  ]
},