How would you design JSON Schema for an arbitrary key? - json

Question

I have the following JSON output data:
{
"label_name_0" : 0,
"label_name_5" : 3,
.
.
.
"label_name_XXX" : 4
}
The output is simple: a key[1] name associated with integer value. If the key name doesn't change, I can easily come up with JSON Schema similar to this:
{
"type": "array"
"title": "Data output",
"items" :{
"properties": {
"label_name": {
"type": "integer",
"default": 0,
"readonly": True,
}
}
},
Since the key name itself is not known and keep changing, I have to design schema for it. The only thing I know is that the key is string and not more than 100 characters. How do I define a JSON Schema for the key lable_name_xxx that keeps changing.
[1] Not sure if I am using the right terminology

Answer 1

On json-schema.org you will find something appropriate in the File System Example section. You can define patternProperties inside an object.
{
"type": "object",
"properties": {
"/": {}
},
"patternProperties": {
"^(label_name_[0-9]+)+$": { "type": "integer" }
},
"additionalProperties": false,
}
The regular expression (label_name_[0-9]+)+ should fit your needs. In JSON Schema regular expressions are explicitly anchored with ^ and $. The regular expressions defines, that there has to be at least one property (+). The property consists of label_name_ and a number between 0 and 9 whereas there has to be at least one number ([0-9]+), but there can also arbitrary many of them.
By setting additionalProperties to false it constrains object properties to match the regular expression.

Answer 2

As Konrad's answer stated, use patternProperties. But use in place of properties, which is not needed, and I think Konrad just pasted from his reference example that was expecting a path starting with /. In the example below, the pattern match regex .* accepts any property name and I am allowing types of string or null only by using "additionalProperties": false.
"patternProperties": {
"^.*$": {
"anyOf": [
{"type": "string"},
{"type": "null"}
]
}
},
"additionalProperties": false

Answer 3

Simpler solution than patternProperties, since OP does not have any requirement on the key names (documentation):
{
"type": "object",
"additionalProperties": {
"type": "integer",
"default": 0,
"readonly": true,
}
}
default and readonly included because they were included in the OP's initial suggestion, but they are not required.