Firebase Schema

• Is your firebase code as big a mess as mine usually is?
• Do you not really know what type of data you save at certain paths?
• Do you even know what your data looks like without logging in?
• Can you access foreign keys and indexes easily?

If you answered "..." to any one of these questions this library is right for you.

Usage

Define your paths in one place (hey, this looks like a route config):

var Firebase = require('firebase');
var FirebaseSchema = require('firebase-schema');
var { string, number, boolean, list, hash, index, key } = FirebaseSchema.Types;

var HOST = 'http://example.firebaseio.com';

// pass in Firebase so you can use this on the server or client
var schema = FirebaseSchema.create(Firebase, HOST, (child) => {
  child('users', list, (child) => {
    child(':userId', hash, (child) => {
      child('name', string);
      child('groups', index('../../groups'), (child) => {
        child(':groupId', boolean);
      });
    });
  });

  child('groups', list, (child) => {
    child(':groupId', hash, (child) => {
      child('name', string);
      child('members', index('../../users'), (child) => {
        child(':userId', boolean)
      });
    });
  });

  child('messages/:groupId', list, (child) => {
    child(':messageId', hash, (child) => {
      child('content', string);
      child('author', key('../../users/:userId'))
    });
  });

  child('messageFlags', list, (child) => {
    child(':flagId', hash, (child) => {
      child('message', key('../../messages/:groupId/:messageId'));
      child('group', key('../../groups/:groupId'));
      child('count', number);
    });
  });
});

• Now its easy to see what kind of data you save and where. Since the schema is defined as a nested route structure, we don't have to leave the key:value paradigm of Firebase.
• Relationships via index and key get looked up for you (https://www.firebase.com/docs/web/guide/structuring-data.html)
• Data is validated when you try to set or push to a path.
• lists are automatically converted to an array when you retrieve the value, with their keys assigned to _id.

var usersRef = schema.createRef('users');
var groupsRef = schema.createRef('groups');
var userId;
var groupId;

usersRef.push({name: 'Ryan'}, () => {
  usersRef.getValue((err, val) => {
    deepEqual(val, [{
      name: 'Ryan',
      // woah what's this? since we did `child('users', list, ...)`
      // we get the values back as an array with their firebase key
      // set as the `_id`
      _id: '-Jev95piCGXV9jX4ellH'
    }])
    userId = val[0]._id;
  });
});

// later

groupsRef.push({name: 123}); // error! should be a string

groupsRef.push({ name: 'cool kids table' }, () => {
  groupsRef.getValue((err, groups) => {
    groupId = groups[0]._id;
    // define a relationship between the group and the user using
    // a `key:true` index (https://www.firebase.com/docs/web/guide/structuring-data.html)
    groupsRef.child(`${groupId}/members/${userId}`).set(true);
    usersRef.child(`${userId}/groups/${groupId}`).set(true);
  });
});

// later

groupsRef.getValue((err, groups) => {
  deepEqual(groups[0], {
    name: 'cool kids table',
    members: { '-Jev95piCGXV9jX4ellH': true },
    _id: '-Jev95pjLLtDmIxbGhcF',
    // woah what's this?
    _indexes: {
      // because we defined `child('members', index(...))` we
      // get an array of paths to the members of this group
      members: [
        'users/-Jev95piCGXV9jX4ellH'
      ]
    }
  }); // true

  // now you can easily go lookup the users from the members
  var userRef = usersRef.child(groups[0]._indexes.members[0]);
});

// keys work similarly
var coolKidMessages = schema.createRef(`messages/${groupId}`);
coolKidMessages.push({
  content: 'guhhhh i hate 3rd period',
  author: userId
});

// later
coolKidMessages.getValue((err, value) => {
  deepEqual(value[0], {
    content: 'guhhhh i hate 3rd period',
    author: '-Jev95piCGXV9jX4ellH',
    _id: '-Jev95pjLLtDmIxbGhcF'
    _links: {
      author: 'users/-Jev95piCGXV9jX4ellH'
    }
  }); // true!
});

That's it. That's where this is at. I haven't used it yet in my app, but am going to soon, will probably need to add in some more of the firebase API to createRef. In the meantime, check out tests.js to see anything I've missed here.