How do I indicate which "oneOf" API response will use? - jsonschema

Question

I have an API where the basic response of one key will have an array of identifiers. A user may pass an extra parameter so the array will turn to an array of objects from an array of strings (for actual details rather than having to make a separate call).
"children": {
"type": "array",
"items": {
"oneOf": [{
"type": "string",
"description": "Identifier of child"
}, {
"type": "object",
"description": "Contains details about the child"
}]
}
},
Is there a way to indicate that the first type comes by a default and the second via a requested param?

Answer 1

It's not entirely clear to me what you are trying to accomplish with the distinction. Really that sounds like documentation; maybe elaborate in the descriptions of each oneOf subschema.
You could add an additional boolean field at the top level (sibling of children) to indicate whether detailed responses are returned and provide a default value for that field. The next step is to couple the value of the boolean to the type of the array items, which I've done using oneOf.
I'm suggesting something along the lines of:
{
"children": {
"type": "array",
"items": {
"oneOf": [
{
"type": "string",
"description": "Identifier of child",
"pattern": "^([A-Z0-9]-?){4}$"
},
{
"type": "object",
"description": "Contains details about the child",
"properties": {
"age": {
"type": "number"
}
}
}
]
}
},
"detailed": {
"type": "boolean",
"description": "If true, children array contains extra details.",
"default": false
},
"oneOf": [
{
"detailed": {
"enum": [
true
]
},
"children": {
"type": "array",
"items": {
"type": "object"
}
}
},
{
"detailed": {
"enum": [
false
]
},
"children": {
"type": "array",
"items": {
"type": "string"
}
}
}
]
}
The second oneOf places a further requirement on the response object that when "detailed": true the type of items of the "children" array must be "object". This refines the first oneOf restriction that describes the schema of objects in the "children" array.