Json schema limit number of the same object - json

Question

Is there a way, to create a json schema, that limits the number a object can occur?
Or make sure, that a object is unique?
In the end, i want something like
{
"days": {
"monday": {
"schedule": {
"start_time": "23:35"
}
},
"tuesday": {
"schedule": {
"start_time": "23:23"
}
}
}
}
In this json, each day should only occur once. Like one start time per day.
So far, i tried it with the following schema but not successful at all.
With this schema, i can have multiple "monday" objects in my json and the schema is still valid. But what i'm looking for, is a schema that is not valid for more than one object.
{
"$schema": "http://json-schema.org/schema#",
"title": "DayScheduler",
"type": "object",
"required": [
"days"
],
"properties": {
"days": {
"monday": {
"$ref": "#/definitions/scheduler"
},
"tuesday": {
"$ref": "#/definitions/scheduler"
},
"wednesday": {
"$ref": "#/definitions/scheduler"
},
"thursday": {
"$ref": "#/definitions/scheduler"
},
"friday": {
"$ref": "#/definitions/scheduler"
},
"saturday": {
"$ref": "#/definitions/scheduler"
},
"sunday": {
"$ref": "#/definitions/scheduler"
}
}
},
"definitions": {
"scheduler": {
"type": "object",
"required": [
"schedule"
],
"properties": {
"schedule": {
"type": "object",
"required": [
"start_time"
],
"properties": {
"start_time": {
"type": "string",
"pattern": "^([01]?[0-9]|2[0-3]):[0-5][0-9]"
}
}
}
}
}
}
}
Is there a way to achieve this with a json-schema?

Answer 1

Duplicate keys are not allowed in JSON. JSON Schema is designed to validate JSON data. It's not equipped to validate data that is not valid JSON.
This example helps illustrate why this is not valid.
var value = {
"foo": 1,
"foo": 2
}
If you evaluate this as a JavaScript object and try to access the foo property of this object: value.foo === ???, is it 1 or 2? It's ambiguous.

Answer 2

My experience in JSON has lead me to understand that if you have multiple objects with the same key, the value of the last one will be taken for the key.
You could try adding
{
"name": name,
type: object,
properties: {
a:b,
c:d
},
"additionalProperties": false
}
to your schema, but I still think the last occurrence of each key will be taken as the value.