Back-converting from JSON draft 4 to JSON draft 3 - json

Question

I have a bit of a weird situation. I am running a JSON schema validator that doesn't support draft 4, and due to corporate wonkiness I'm stuck with it instead of replacing it. Our developers are giving me schemas in draft 4 format, so I have to go through by hand and back-convert it, particularly the required fields.
This has all worked fine up until I hit something like this (consider this pseudo-code; I'm still getting the hang of JSON):
"items": {
"type": "array",
"required" : true,
"items": [
{...},
"required": ["0", "1"] // This bit right here
],
}
I'm told it basically says, "The first two items in the array are required." But I can't find a way to express that in JSON draft 3. Is that even supported, and if so, how would you express it?

Answer 1

required is a keyword that only has meaning for object instances, not for arrays.
The way to indicate that an array must have at least 2 items is through minItems keyword in both Draft3 and Draft4.
If you need to express any other schema just for the first and second item in an array, you do it by having two schemas in the items array. For instance, the following schema requires that properties "0" and "1" are included in the first and second items in the array.
For Draft 3:
"items" : [{
"properties" : {
"0" : {"required" : true},
"1" : {"required" : true}
}
}, {
"properties" : {
"0" : {"required" : true},
"1" : {"required" : true}
}
}
]
And Draft 4:
"items" : [{
"required" : ["0", "1"]
}, {
"required" : ["0", "1"]
}
]