JSONSchema - Element can appear alone or within a group - json

Question

I have a JSON that looks like this:
{
"name": "Jane",
"company_name": "BrandNewStartup",
"designation": "DesignLead"
}
The name element can appear alone in the JSON as well, so the following JSON is valid too.
{
"name": "Jane"
}
But company_name and designation cannot appear if name is missing. So the following JSON should be invalid:
{
"company_name": "BrandNewStartup",
"designation": "DesignLead"
}
I have tried the following rule:
"oneOf": [
{
"required": [
"name",
"company_name",
"designation"
]
},
{
"required": [
"name"
]
}
]
However this does not seem to work (e.g this validation library raises error that the JSON should be valid to only one schema but it is valid against all).
If I change this to anyOf, the first JSON with all the 3 fields works, but when name appears alone, an error is raised that the company_name designation fields are missing.
How do I define this rule?

Answer 1

JSON Schema is a constraints based language. Anything you don't specify is allowed.
The required keyword means a key is required in an object, but doesn't inherintly prevent any other keys from being included.
Breaking down the schema in your question, when you have all three keys in your object, as in your first example instance, then both subschemas in oneOf would be valid.
In order to restrict the allowed properties, you need to use the additionalProperties keyword, which in your case also means you need to use the properties keyword. required has no effect on additionalProperties.
The second subschema needs to only be valid when the instance has ONLY name and no other keys. Here's a live demo using the below modified JSON Schema: https://jsonschema.dev/s/7JcUa
{
"$schema": "http://json-schema.org/draft-07/schema",
"oneOf": [
{
"required": [
"name",
"company_name",
"designation"
]
},
{
"required": [
"name"
],
"properties": {
"name": true
},
"additionalProperties": false
}
]
}