Model Firebase realtime database in JSON schema - firebase

Question

The Firebase database uses a subset of JSON. Thus it seems obvious to use JSON schema to describe the data model. This would allow to make use of tools which generate HTML forms or typescript models from it or generate random test data.
My question: How would one model key-value pairs in JSON schema, where the key is an id?
Example: (borrowed from firebase spec)
{
"users": {
"mchen": {
"name": "Mary Chen",
// index Mary's groups in her profile
"groups": {
// the value here doesn't matter, just that the key exists
"alpha": true,
"charlie": true
}
},
...
The group name here is used as an group id. In this reference (groups object) as well as in the group object itself, the id is used as the property name.
JSON schema for above example is:
{
"$schema": "http://json-schema.org/draft-04/schema#",
"type": "object",
"properties": {
"users": {
"type": "object",
"properties": {
"mchen": {
"type": "object",
"properties": {
"name": {
"type": "string"
},
"groups": {
"type": "object",
"properties": {
"alpha": {
"type": "boolean"
},
"charlie": {
"type": "boolean"
}
}
}
}
}
}
}
}
}
What I would need for the example is something like the following, where NAME is a placeholder for the property name and NAME_TYPE defines it's type.
{
"$schema": "http://json-schema.org/draft-04/schema#",
"type": "object",
"properties": {
"users": {
"type": "object",
"properties": {
NAME: {
"type": "object",
NAME_TYPE: "string",
"properties": {
"name": {
"type": "string"
},
"groups": {
"type": "object",
"properties": {
NAME: {
NAME_TYPE: "string"
"type": "boolean"
}
}
}
}
}
}
}
}
}
(Maybe I am on the completely wrong path here or maybe JSON schema isn't able to model the required structure.)

Answer 1

There are certainly arrays in Firebase but they are situational and should be used only in certain use cases and should generally be avoided.
The Firebase structure you posted is very common and there are key:value pairs in your structure so the question is a tad unclear but I'll give it a shot.
'groups' is the parent key and the values are the children key:value pairs of group1:value, group2:value.
The group1, group2 keys you listed are essentially the same as the id's listed in the first example, other than it's not an array. i.e. array's have sequential, hard coded-indexes (0th, 1st, 2nd etc) whereas the keys in firebase are open-ended and can generally be set to any alphanumeric value - they are used more to refer to a specific node than the enforce an particular order (i'm speaking generally here)
In the Firebase structure, those keys could be id0, id1, id2... or a,b,c... or a timestamp... or an auto-generated Firebase id (childByAutoId) that would also make them 'sequential'.
However, you can get into trouble assigning your own with id0, id1 etc.
id0
id1
id2
.
id9
id10
id11
The reality here is that the actual order will be
id0
id1
id10
id11
id2
The 'key' is that if you are using the keys to read data in sequentially, set them up as such. You may also want to consider generating your keys with childByAutoId (see docs for language specifics) and orderBy one of the child values such as a timestamp or index.
'groups': {
'auto-generated id': {
'name': 'alpha',
'index': 0,
'timestamp': '20160814074146'
...
},
'auto-generated id': {
'name': 'charlie',
'index': 1,
'timestamp': '20160814073600'
...
},
...
}
in the above case, I can orderBy name, index or timestamp.
Name and index will read the nodes in the order they are listed, if we order by timestamp, then the charlie node will be loaded first. Leveraging the child values to orderBy is very flexible.
Also, you can limit the set of data you are loading in with startingAt and endingAt. So for example, you want to load nodes starting at node 10 and ending at node 14. Easily done with non-array JSON data but not easily done if it's stored in an array as the entire array must be read in.