Json Schema matching with 'anyOf' - json

Question

I'd like to be able to manage a json array of 'objects' where each object has a type and properties, and there's a schema error if a mandatory property is missing from an object.
This is my attempt to do this (not including the array part) declaring two object types and saying the object in the json can be either of those types:
{
'definitions':
{
'typeone':
{
'type': 'object',
'properties':
{
'xtype': {'type':'string', 'const':'typeone'},
'num' : {'type':'number'}
},
'required':['xtype', 'num'],
'additionalProperties':false
},
'typetwo':
{
'type': 'object',
'properties':
{
'xtype': {'type':'string', 'const':'typetwo'},
'str' : {'type':'string'}
},
'required':['xtype', 'str'],
'additionalProperties':false
}
},
'anyOf':
[
{ '$ref': '#/definitions/typeone' },
{ '$ref': '#/definitions/typetwo' },
]
}
However, if I feed it json which fails because a mandatory property is missing from an object like this:
{
'xtype': 'typeone'
}
...it errors with JSON does not match any schemas from 'anyOf'. - I can see the reason is that it doesn't know to try to match on the xtype, instead it just considers xtype of 'typeone' invalid and looks to others.
Is there a better way to do anyOf which will hard-match based on one property value (like a 'switch') then give errors about missing other mandatory properties for that object type?

Answer 1

It gets a lot more verbose, but you can use if/then to switch validation based on the "xtype" property.
{
"$schema": "http://json-schema.org/draft-07/schema#",
"allOf": [
{
"if": {
"type": "object",
"properties": {
"xtype": { "const": "typeone" }
},
"required": ["xtype"]
},
"then": { "$ref": "#/definitions/typeone" }
},
{
"if": {
"type": "object",
"properties": {
"xtype": { "const": "typetwo" }
},
"required": ["xtype"]
},
"then": { "$ref": "#/definitions/typetwo" }
}
],
"definitions": {
"typeone": {
"type": "object",
"properties": {
"xtype": {},
"num": { "type": "number" }
},
"required": ["num"],
"additionalProperties": false
},
"typetwo": {
"type": "object",
"properties": {
"xtype": {},
"str": { "type": "string" }
},
"required": ["str"],
"additionalProperties": false
}
}
}
With a small change to the model, you could use dependencies to get a much simpler cleaner schema. Instead of having an "xtytpe" property, you can have a property corresponding to the name of the type. For example, { "typeone": true }.
{
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "object",
"dependencies": {
"typeone": {
"type": "object",
"properties": {
"typeone": {},
"num": { "type": "number" }
},
"required": ["num"],
"additionalProperties": false
},
"typetwo": {
"type": "object",
"properties": {
"typetwo": {},
"str": { "type": "string" }
},
"required": ["str"],
"additionalProperties": false
}
}
}