Firebase - Lesson 5 - Rules and Datastructure for Account Merge Example

firebase-data.json

{
  "acknowledge" : {
    "merges" : {
      "accepted" : {
        "898dac5d-f99d-463a-b82a-54abd5784447" : "google:106385094246122969144"
      },
      "proposed" : {
        "898dac5d-f99d-463a-b82a-54abd5784447" : "google:106385094246122969144"
      }
    },
    "messages" : {
      "-K61_SOkAM3L8U8-DN97" : {
        "timestamp" : 1450668578467,
        "uid" : "google:106385094246122969144"
      },
      "-K652RtRKLRH2pjiBw25" : {
        "timestamp" : 1450726772361,
        "uid" : "google:106385094246122969144"
      },
      "-K65pKKz5ZwTPurw8fdw" : {
        "timestamp" : 1450739848629,
        "uid" : "google:106385094246122969144"
      },
      "-K65rVrEDWQce0oA-SQ3" : {
        "timestamp" : 1450740420094,
        "uid" : "google:106385094246122969144"
      },
      "-K65rZfG7TX5ko77Q5eY" : {
        "timestamp" : 1450740435712,
        "uid" : "google:106385094246122969144"
      }
    },
    "users" : {
      "4c9f4097-fe2d-4d22-8a17-b9480c2dc4e6" : {
        "email" : "puf@puf.com",
        "isTemporaryPassword" : false,
        "profileImageURL" : "https://secure.gravatar.com/avatar/5ad89db23b9e5d5f00ba5548cc9e34ec?d=retro"
      },
      "898dac5d-f99d-463a-b82a-54abd5784447" : {
        "email" : "frank@puf.com",
        "isTemporaryPassword" : false,
        "profileImageURL" : "https://secure.gravatar.com/avatar/4df6cf8a2fa4219b0990c579e3f5cffd?d=retro"
      },
      "google:106385094246122969144" : {
        "accessToken" : "ya29.VAJtNRocmDS-eoWNpIxzKInpNsp9fIb5vWqINB2PTyizDJBhrPj_yd5BqFyndzuFvNmg3_E",
        "cachedUserProfile" : {
          "email" : "frank@puf.com",
          "family_name" : "van Puffelen",
          "gender" : "male",
          "given_name" : "Frank",
          "id" : "106385094246122969144",
          "link" : "https://plus.google.com/+FrankvanPuffelen",
          "locale" : "en",
          "name" : "Frank van Puffelen",
          "picture" : "https://lh3.googleusercontent.com/-5w08FC_pwUk/AAAAAAAAAAI/AAAAAAAAGio/aFRsRcln4bg/photo.jpg",
          "verified_email" : true
        },
        "displayName" : "Frank van Puffelen",
        "email" : "frank@puf.com",
        "id" : "106385094246122969144",
        "profileImageURL" : "https://lh3.googleusercontent.com/-5w08FC_pwUk/AAAAAAAAAAI/AAAAAAAAGio/aFRsRcln4bg/photo.jpg"
      }
    }
  },
  "pairing" : {
    "merges" : {
      "accepted" : {
        "898dac5d-f99d-463a-b82a-54abd5784447" : "google:106385094246122969144"
      }
    },
    "messages" : {
      "-K6QOckahwR6H0GtOb4W" : {
        "timestamp" : 1451084909670,
        "uid" : "898dac5d-f99d-463a-b82a-54abd5784447"
      },
      "-K6W1RC_QpUWb9ASrqqu" : {
        "timestamp" : 1451179492235,
        "uid" : "898dac5d-f99d-463a-b82a-54abd5784447"
      },
      "-K6W2ANnHE75uqjtYWND" : {
        "timestamp" : 1451179685465,
        "uid" : "google:106385094246122969144"
      }
    },
    "users" : {
      "898dac5d-f99d-463a-b82a-54abd5784447" : {
        "email" : "frank@puf.com",
        "isTemporaryPassword" : false,
        "profileImageURL" : "https://secure.gravatar.com/avatar/4df6cf8a2fa4219b0990c579e3f5cffd?d=retro"
      },
      "google:106385094246122969144" : {
        "accessToken" : "ya29.VwK66CG-nQIJHva5zpi1YxcATWWEDriauAr6eNB_byKooF_k4KHKuykdfxAPw1DtmNsLtLw",
        "cachedUserProfile" : {
          "email" : "frank@puf.com",
          "family_name" : "van Puffelen",
          "gender" : "male",
          "given_name" : "Frank",
          "id" : "106385094246122969144",
          "link" : "https://plus.google.com/+FrankvanPuffelen",
          "locale" : "en",
          "name" : "Frank van Puffelen",
          "picture" : "https://lh3.googleusercontent.com/-5w08FC_pwUk/AAAAAAAAAAI/AAAAAAAAGio/aFRsRcln4bg/photo.jpg",
          "verified_email" : true
        },
        "displayName" : "Frank van Puffelen",
        "email" : "frank@puf.com",
        "id" : "106385094246122969144",
        "profileImageURL" : "https://lh3.googleusercontent.com/-5w08FC_pwUk/AAAAAAAAAAI/AAAAAAAAGio/aFRsRcln4bg/photo.jpg"
      }
    }
  }
}

rules.json

{
  // This rules file contains two merging strategies:
  // 1. acknowledge - requires user A to propose a merge and user B to accept it. Once accepted, the user A
  //                  can only write messages which have user B as the uid.
  // 2. pairings - User A generates a secret (that is written into the database) that they send to user B, 
  //               user B enters the secret, which then starts the merge process of approach #1
  "rules": {
    "acknowledge": {
      ".read": true,
        "users": {
          "$uid": {
            ".write": "auth.uid == $uid"
          }
        },
        "merges": {
          // there are two lists here: proposed and accepted merges. Both are a mapping from uid of users A to uid of user B in the first explanation
          "proposed": {
            ".indexOn": [".value"],
            "$uid": {
              // a merge can only be proposed by the current user
              ".write": "$uid == auth.uid"
            }
          },
          "accepted": {
            "$uid": {
              // a merge can only be accepted by the user who is targetted in the merge and only when the merge has been proposed
              ".write": "auth.uid == newData.val() && newData.parent().parent().child('proposed').child($uid).val() == newData.val() "
            }
          }
        },
        "messages": {
          // unmerged users can write messages under their own uid. Merged users can write messages under their merge target's uid.
          "$messageid": {
            ".write": "(!newData.parent().parent().child('merges/accepted').child(auth.uid).exists() && auth.uid === newData.child('uid').val()) ||
                       ( newData.parent().parent().child('merges/accepted').child(auth.uid).val() == newData.child('uid').val() )
                      "
          }
        }
      },
      "pairing": {
        "users": {
          ".read": true,
          "$uid": {
            ".write": "auth.uid == $uid"
          }
        },
        "pairingCodes": {
          // this node contains a list of pairing codes. The list itself is not readable, which prevents people from looking up all pairingCodes
          "$code": {
            // a pairing code consists of a uid and a timestamp. The uid identifies the user that generated the code.
            ".validate": "newData.hasChildren(['uid', 'timestamp'])",
            // you can read a specific pairingCode if you know it and it's less than a minute old
            ".read": "data.child('timestamp').val() + 60000 > now",
            // you can only write data if nothing exists yet, or delete existing data
            ".write": "(newData.exists() && !data.exists()) || (data.exists() && !newData.exists())",
            "timestamp": {
              ".validate": "newData.val() == now"
            }
          }
        },
        "merges": {
          // the rules for the merges are the same as in the first approach
          ".read": true,
          "proposed": {
            ".indexOn": [".value"],
            "$uid": {
              ".write": "$uid == auth.uid || newData.parent().parent().child('accepted').child($uid).val() == auth.uid"
            }
          },
          "accepted": {
            "$uid": {
              ".write": "auth.uid == newData.val() &&
                         data.parent().parent().child('proposed').child($uid).val() == newData.val() &&
                          !newData.parent().parent().child('proposed').child($uid).exists()
                        "
            }
          }
        },
        "messages": {
          ".read": true,
          "$messageid": {
            ".write": "(!newData.parent().parent().child('merges/accepted').child(auth.uid).exists() && auth.uid === newData.child('uid').val()) ||
                       ( newData.parent().parent().child('merges/accepted').child(auth.uid).val() == newData.child('uid').val() )
                      "
          }
        }
      }
    }
}

Great Job :) ThnQ